Publications

@article{pmid24683502,

title = {Towards Clinically Optimized MRI-guided Surgical Manipulator for Minimally Invasive Prostate Percutaneous Interventions: Constructive Design},

author = {Sohrab Eslami and Gregory S Fischer and Sang-Eun Song and Junichi Tokuda and Nobuhiko Hata and Clare M Tempany and Iulian Iordachita},

doi = {10.1109/ICRA.2013.6630728},

issn = {2152-4092},

year  = {2013},

date = {2013-12-01},

journal = {IEEE Int Conf Robot Autom},

volume = {20132},

pages = {1228--1233},

abstract = {This paper undertakes the modular design and development of a minimally invasive surgical manipulator for MRI-guided transperineal prostate interventions. Severe constraints for the MRI-compatibility to hold the minimum artifact on the image quality and dimensions restraint of the bore scanner shadow the design procedure. Regarding the constructive design, the manipulator kinematics has been optimized and the effective analytical needle workspace is developed and followed by proposing the workflow for the manual needle insertion. A study of the finite element analysis is established and utilized to improve the mechanism weaknesses under some inevitable external forces to ensure the minimum structure deformation. The procedure for attaching a sterile plastic drape on the robot manipulator is discussed. The introduced robotic manipulator herein is aimed for the clinically prostate biopsy and brachytherapy applications.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid23335658,

title = {Development and preliminary evaluation of a motorized needle guide template for MRI-guided targeted prostate biopsy},

author = {Sang-Eun Song and Junichi Tokuda and Kemal Tuncali and Clare M Tempany and Elizabeth Zhang and Nobuhiko Hata},

doi = {10.1109/TBME.2013.2240301},

issn = {1558-2531},

year  = {2013},

date = {2013-11-01},

journal = {IEEE Trans Biomed Eng},

volume = {60},

number = {11},

pages = {3019--3027},

abstract = {To overcome the problems of limited needle insertion accuracy and human error in the use of a conventional needle guide template in magnetic resonance imaging (MRI)-guided prostate intervention, we developed a motorized MRI-compatible needle guide template that resembles a transrectal ultrasound-guided prostate template. The motorized template allows automated, gapless needle guidance in a 3T MRI scanner with minimal changes in the current clinical procedure. To evaluate the impact of the motorized template on MRI, signal-to-noise ratio and distortion were measured under various system configurations. A maximum of 44% signal-to-noise ratio decrease was found when the ultrasonic motors were running, and a maximum of 0.4% image distortion was observed due to the presence of the motorized template. To measure needle insertion accuracy, we performed four sets of five random target needle insertions mimicking four biopsy procedures, which resulted in an average in-plane targeting error of 0.94 mm with a standard deviation of 0.34 mm. The evaluation studies indicated that the presence and operation of the motorized template in the MRI bore create insignificant image degradation, and provide submillimeter targeting accuracy. The automated needle guide that is directly controlled by navigation software eliminates human error so that the safety of the procedure can be improved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{song_development_2013,

title = {Development and Preliminary Evaluation of a Motorized Needle Guide Template for MRI-Guided Targeted Prostate Biopsy},

author = {Sang-Eun Song and Junichi Tokuda and Kemal Tuncali and Clare M. Tempany and Elizabeth Zhang and Nobuhiko Hata},

doi = {10.1109/TBME.2013.2240301},

issn = {0018-9294, 1558-2531},

year  = {2013},

date = {2013-11-01},

journal = {IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING},

volume = {60},

number = {11},

pages = {3019–3027},

abstract = {To overcome the problems of limited needle insertion accuracy and human error in the use of a conventional needle guide template in magnetic resonance imaging (MRI)-guided prostate intervention, we developed a motorized MRI-compatible needle guide template that resembles a transrectal ultrasound-guided prostate template. The motorized template allows automated, gapless needle guidance in a 3T MRI scanner with minimal changes in the current clinical procedure. To evaluate the impact of the motorized template on MRI, signal-to-noise ratio and distortion were measured under various system configurations. A maximum of 44% signal-to-noise ratio decrease was found when the ultrasonic motors were running, and a maximum of 0.4% image distortion was observed due to the presence of the motorized template. To measure needle insertion accuracy, we performed four sets of five random target needle insertions mimicking four biopsy procedures, which resulted in an average in-plane targeting error of 0.94 mm with a standard deviation of 0.34 mm. The evaluation studies indicated that the presence and operation of the motorized template in the MRI bore create insignificant image degradation, and provide submillimeter targeting accuracy. The automated needle guide that is directly controlled by navigation software eliminates human error so that the safety of the procedure can be improved.},

note = {Num Pages: 9 

Place: Piscataway 

Publisher: Ieee-Inst Electrical Electronics Engineers Inc 

Web of Science ID: WOS:000325974500005},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{seifabadi_accuracy_2013,

title = {Accuracy study of a robotic system for MRI-guided prostate needle placement},

author = {Reza Seifabadi and Nathan B. J. Cho and Sang-Eun Song and Junichi Tokuda and Nobuhiko Hata and Clare M. Tempany and Gabor Fichtinger and Iulian Iordachita},

doi = {10.1002/rcs.1440},

issn = {1478-5951, 1478-596X},

year  = {2013},

date = {2013-09-01},

journal = {INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY},

volume = {9},

number = {3},

pages = {305–316},

abstract = {BackgroundAccurate needle placement is the first concern in percutaneous MRI-guided prostate interventions. In this phantom study, different sources contributing to the overall needle placement error of a MRI-guided robot for prostate biopsy have been identified, quantified and minimized to the possible extent. MethodsThe overall needle placement error of the system was evaluated in a prostate phantom. This error was broken into two parts: the error associated with the robotic system (called before-insertion error') and the error associated with needle-tissue interaction (called due-to-insertion error'). Before-insertion error was measured directly in a soft phantom and different sources contributing into this part were identified and quantified. A calibration methodology was developed to minimize the 4-DOF manipulator's error. The due-to-insertion error was indirectly approximated by comparing the overall error and the before-insertion error. The effect of sterilization on the manipulator's accuracy and repeatability was also studied. ResultsThe average overall system error in the phantom study was 2.5mm (STD=1.1mm). The average robotic system error in the Super Soft plastic phantom was 1.3mm (STD=0.7mm). Assuming orthogonal error components, the needle-tissue interaction error was found to be approximately 2.13mm, thus making a larger contribution to the overall error. The average susceptibility artifact shift was 0.2mm. The manipulator's targeting accuracy was 0.71mm (STD=0.21mm) after robot calibration. The robot's repeatability was 0.13mm. Sterilization had no noticeable influence on the robot's accuracy and repeatability. ConclusionsThe experimental methodology presented in this paper may help researchers to identify, quantify and minimize different sources contributing into the overall needle placement error of an MRI-guided robotic system for prostate needle placement. In the robotic system analysed here, the overall error of the studied system remained within the acceptable range. Copyright (c) 2012 John Wiley & Sons, Ltd.},

note = {Num Pages: 12 

Place: Hoboken 

Publisher: Wiley 

Web of Science ID: WOS:000329507500011},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid25076821,

title = {A Fully Actuated Robotic Assistant for MRI-Guided Prostate Biopsy and Brachytherapy},

author = {Gang Li and Hao Su and Weijian Shang and Junichi Tokuda and Nobuhiko Hata and Clare M Tempany and Gregory S Fischer},

doi = {10.1117/12.2007669},

issn = {0277-786X},

year  = {2013},

date = {2013-03-01},

journal = {Proc SPIE Int Soc Opt Eng},

volume = {8671},

pages = {867117},

abstract = {Intra-operative medical imaging enables incorporation of human experience and intelligence in a controlled, closed-loop fashion. Magnetic resonance imaging (MRI) is an ideal modality for surgical guidance of diagnostic and therapeutic procedures, with its ability to perform high resolution, real-time, high soft tissue contrast imaging without ionizing radiation. However, for most current image-guided approaches only static pre-operative images are accessible for guidance, which are unable to provide updated information during a surgical procedure. The high magnetic field, electrical interference, and limited access of closed-bore MRI render great challenges to developing robotic systems that can perform inside a diagnostic high-field MRI while obtaining interactively updated MR images. To overcome these limitations, we are developing a piezoelectrically actuated robotic assistant for actuated percutaneous prostate interventions under real-time MRI guidance. Utilizing a modular design, the system enables coherent and straight forward workflow for various percutaneous interventions, including prostate biopsy sampling and brachytherapy seed placement, using various needle driver configurations. The unified workflow compromises: 1) system hardware and software initialization, 2) fiducial frame registration, 3) target selection and motion planning, 4) moving to the target and performing the intervention (e.g. taking a biopsy sample) under live imaging, and 5) visualization and verification. Phantom experiments of prostate biopsy and brachytherapy were executed under MRI-guidance to evaluate the feasibility of the workflow. The robot successfully performed fully actuated biopsy sampling and delivery of simulated brachytherapy seeds under live MR imaging, as well as precise delivery of a prostate brachytherapy seed distribution with an RMS accuracy of 0.98mm.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{song_workspace-orientated_2013,

title = {A workspace-orientated needle-guiding robot for 3T MRI-guided transperineal prostate intervention: evaluation of in-bore workspace and MRI compatibility},

author = {Sang-Eun Song and Nobuhiko Hata and Iulian Iordachita and Gabor Fichtinger and Clare Tempany and Junichi Tokuda},

doi = {10.1002/rcs.1430},

issn = {1478-5951, 1478-596X},

year  = {2013},

date = {2013-03-01},

journal = {INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY},

volume = {9},

number = {1},

pages = {67–74},

abstract = {Background Magnetic resonance imaging (MRI)-guided prostate interventions have been introduced to enhance the cancer detection. For accurate needle positioning, in-bore-operated robotic systems have been developed and optimal use of the confined in-bore space become a critical engineering challenge. Methods As preliminary evaluation of our prostate intervention robot, we conducted a workspace design analysis, using a new evaluation method that we developed for in-bore-operated robots for transperineal prostate interventions, and an MRI compatibility study. Results The workspace analysis resulted in the effective workspace (VW) of 0.32, which is greater than that of our early prototype, despite the current robot being ca. 50% larger than the early prototype in sectional space. The MRI compatibility study resulted in<15% signal:noise ratio (SNR) reduction. Conclusions The new workspace evaluation method quantifies the workspace utilization of the in-bore-operated robots for MRI-guided transperineal prostate interventions, providing a useful tool for evaluation and new robot design. The robot creates insignificant electromagnetic noise during typical prostate imaging sequences. Copyright (c) 2012 John Wiley & Sons, Ltd.},

note = {Num Pages: 8 

Place: Hoboken 

Publisher: Wiley 

Web of Science ID: WOS:000315900500012},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid24505781,

title = {Configurable automatic detection and registration of fiducial frames for device-to-image registration in MRI-guided prostate interventions},

author = {Junichi Tokuda and Sang-Eun Song and Kemal Tuncali and Clare Tempany and Nobuhiko Hata},

doi = {10.1007/978-3-642-40760-4_45},

year  = {2013},

date = {2013-01-01},

journal = {Med Image Comput Comput Assist Interv},

volume = {16},

number = {Pt 3},

pages = {355--362},

abstract = {We propose a novel automatic fiducial frame detection and registration method for device-to-image registration in MRI-guided prostate interventions. The proposed method does not require any manual selection of markers, and can be applied to a variety of fiducial frames, which consist of multiple cylindrical MR-visible markers placed in different orientations. The key idea is that automatic extraction of linear features using a line filter is more robust than that of bright spots by thresholding; by applying a line set registration algorithm to the detected markers, the frame can be registered to the MRI. The method was capable of registering the fiducial frame to the MRI with an accuracy of 1.00 +/- 0.73 mm and 1.41 +/- 1.06 degrees in a phantom study, and was sufficiently robust to detect the fiducial frame in 98% of images acquired in clinical cases despite the existence of anatomical structures in the field of view.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid24505687,

title = {Multi-section continuum robot for endoscopic surgical clipping of intracranial aneurysms},

author = {Takahisa Kato and Ichiro Okumura and Sang-Eun Song and Nobuhiko Hata},

doi = {10.1007/978-3-642-40811-3_46},

year  = {2013},

date = {2013-01-01},

journal = {Med Image Comput Comput Assist Interv},

volume = {16},

number = {Pt 1},

pages = {364--371},

abstract = {We propose the development and assessment of a multi-section continuum robot for endoscopic surgical clipping of intracranial aneurysms. The robot has two sections for bending actuated by tendon wires. By actuating the two sections independently, the robot can generate a variety of posture combinations by these sections while maintaining the tip angle. This feature offers more flexibility in positioning of the tip than a conventional endoscope for large viewing angles of up to 180 degrees. To estimate the flexible positioning of the tip, we developed kinematic mapping with friction in tendon wires. In a kinematic-mapping simulation, the two-section robot at the target scale (i.e., an outer diameter of 1.7 mm and a length of 60 mm) had a variety of tip positions within 50-mm ranges at the 180 degree-angled view. In the experimental validation, the 1:10 scale prototype performed the three salient postures with different tip positions at the 1800-angled view.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{tokuda_preclinical_2012,

title = {Preclinical evaluation of an MRI-compatible pneumatic robot for angulated needle placement in transperineal prostate interventions},

author = {Junichi Tokuda and Sang-Eun Song and Gregory S. Fischer and Iulian I. Iordachita and Reza Seifabadi and Nathan B. Cho and Kemal Tuncali and Gabor Fichtinger and Clare M. Tempany and Nobuhiko Hata},

doi = {10.1007/s11548-012-0750-1},

issn = {1861-6410, 1861-6429},

year  = {2012},

date = {2012-11-01},

journal = {INTERNATIONAL JOURNAL OF COMPUTER ASSISTED RADIOLOGY AND SURGERY},

volume = {7},

number = {6},

pages = {949–957},

abstract = {Purpose To evaluate the targeting accuracy of a small profile MRI-compatible pneumatic robot for needle placement that can angulate a needle insertion path into a large accessible target volume. Methods We extended our MRI-compatible pneumatic robot for needle placement to utilize its four degrees-of-freedom (4-DOF) mechanism with two parallel triangular structures and support transperineal prostate biopsies in a closed-bore magnetic resonance imaging (MRI) scanner. The robot is designed to guide a needle toward a lesion so that a radiologist can manually insert it in the bore. The robot is integrated with navigation software that allows an operator to plan angulated needle insertion by selecting a target and an entry point. The targeting error was evaluated while the angle between the needle insertion path and the static magnetic field was between -5.7 degrees and 5.7 degrees horizontally and between -5.7 degrees and 4.3 degrees vertically in the MRI scanner after sterilizing and draping the device. Results The robot positioned the needle for angulated insertion as specified on the navigation software with overall targeting error of 0.8 +/- 0.5mm along the horizontal axis and 0.8 +/- 0.8mm along the vertical axis. The two-dimensional root-mean-square targeting error on the axial slices as containing the targets was 1.4mm. Conclusions Our preclinical evaluation demonstrated that the MRI-compatible pneumatic robot for needle placement with the capability to angulate the needle insertion path provides targeting accuracy feasible for clinical MRI-guided prostate interventions. The clinical feasibility has to be established in a clinical study.},

note = {Num Pages: 9 

Place: Heidelberg 

Publisher: Springer Heidelberg 

Web of Science ID: WOS:000310540800016},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid22645031,

title = {Image registration for targeted MRI-guided transperineal prostate biopsy},

author = {Andriy Fedorov and Kemal Tuncali and Fiona M Fennessy and Junichi Tokuda and Nobuhiko Hata and William M Wells and Ron Kikinis and Clare M Tempany},

doi = {10.1002/jmri.23688},

issn = {1522-2586},

year  = {2012},

date = {2012-10-01},

journal = {J Magn Reson Imaging},

volume = {36},

number = {4},

pages = {987--992},

abstract = {PURPOSE: To develop and evaluate image registration methodology for automated re-identification of tumor-suspicious foci from preprocedural MR exams during MR-guided transperineal prostate core biopsy.nnMATERIALS AND METHODS: A hierarchical approach for automated registration between planning and intra-procedural T2-weighted prostate MRI was developed and evaluated on the images acquired during 10 consecutive MR-guided biopsies. Registration accuracy was quantified at image-based landmarks and by evaluating spatial overlap for the manually segmented prostate and sub-structures. Registration reliability was evaluated by simulating initial mis-registration and analyzing the convergence behavior. Registration precision was characterized at the planned biopsy targets.nnRESULTS: The total computation time was compatible with a clinical setting, being at most 2 min. Deformable registration led to a significant improvement in spatial overlap of the prostate and peripheral zone contours compared with both rigid and affine registration. Average in-slice landmark registration error was 1.3 ± 0.5 mm. Experiments simulating initial mis-registration resulted in an estimated average capture range of 6 mm and an average in-slice registration precision of ±0.3 mm.nnCONCLUSION: Our registration approach requires minimum user interaction and is compatible with the time constraints of our interventional clinical workflow. The initial evaluation shows acceptable accuracy, reliability and consistency of the method.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{fedorov_image_2012,

title = {Image registration for targeted MRI-guided transperineal prostate biopsy},

author = {Andriy Fedorov and Kemal Tuncali and Fiona M. Fennessy and Junichi Tokuda and Nobuhiko Hata and William M. Wells and Ron Kikinis and Clare M. Tempany},

doi = {10.1002/jmri.23688},

issn = {1053-1807, 1522-2586},

year  = {2012},

date = {2012-10-01},

journal = {JOURNAL OF MAGNETIC RESONANCE IMAGING},

volume = {36},

number = {4},

pages = {987–992},

abstract = {Purpose: To develop and evaluate image registration methodology for automated re-identification of tumor-suspicious foci from preprocedural MR exams during MR-guided transperineal prostate core biopsy. Materials and Methods: A hierarchical approach for automated registration between planning and intra-procedural T2-weighted prostate MRI was developed and evaluated on the images acquired during 10 consecutive MR-guided biopsies. Registration accuracy was quantified at image-based landmarks and by evaluating spatial overlap for the manually segmented prostate and sub-structures. Registration reliability was evaluated by simulating initial mis-registration and analyzing the convergence behavior. Registration precision was characterized at the planned biopsy targets. Results: The total computation time was compatible with a clinical setting, being at most 2 min. Deformable registration led to a significant improvement in spatial overlap of the prostate and peripheral zone contours compared with both rigid and affine registration. Average in-slice landmark registration error was 1.3 +/- 0.5 mm. Experiments simulating initial mis-registration resulted in an estimated average capture range of 6 mm and an average in-slice registration precision of +/-0.3 mm. Conclusion: Our registration approach requires minimum user interaction and is compatible with the time constraints of our interventional clinical workflow. The initial evaluation shows acceptable accuracy, reliability and consistency of the method. J. Magn. Reson. Imaging 2012;36:987992. (c) 2012 Wiley Periodicals, Inc.},

note = {Num Pages: 6 

Place: Hoboken 

Publisher: Wiley-Blackwell 

Web of Science ID: WOS:000308884300025},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid22374845,

title = {Integration of the OpenIGTLink network protocol for image-guided therapy with the medical platform MeVisLab},

author = {Jan Egger and Junichi Tokuda and Laurent Chauvin and Bernd Freisleben and Christopher Nimsky and Tina Kapur and William Wells},

doi = {10.1002/rcs.1415},

issn = {1478-596X},

year  = {2012},

date = {2012-09-01},

journal = {Int J Med Robot},

volume = {8},

number = {3},

pages = {282--290},

abstract = {BACKGROUND: OpenIGTLink is a new, open, simple and extensible network communication protocol for image-guided therapy (IGT). The protocol provides a standardized mechanism to connect hardware and software by the transfer of coordinate transforms, images, and status messages. MeVisLab is a framework for the development of image processing algorithms and visualization and interaction methods, with a focus on medical imaging.nnMETHODS: The paper describes the integration of the OpenIGTLink network protocol for IGT with the medical prototyping platform MeVisLab. The integration of OpenIGTLink into MeVisLab has been realized by developing a software module using the C++ programming language.nnRESULTS: The integration was evaluated with tracker clients that are available online. Furthermore, the integration was used to connect MeVisLab to Slicer and a NDI tracking system over the network. The latency time during navigation with a real instrument was measured to show that the integration can be used clinically.nnCONCLUSIONS: Researchers using MeVisLab can interface their software to hardware devices that already support the OpenIGTLink protocol, such as the NDI Aurora magnetic tracking system. In addition, the OpenIGTLink module can also be used to communicate directly with Slicer, a free, open source software package for visualization and image analysis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{tokuda_-bore_2012,

title = {In-bore setup and software for 3T MRI-guided transperineal prostate biopsy},

author = {Junichi Tokuda and Kemal Tuncali and Iulian Iordachita and Sang-Eun Song and Andriy Fedorov and Sota Oguro and Andras Lasso and Fiona M. Fennessy and Clare M. Tempany and Nobuhiko Hata},

doi = {10.1088/0031-9155/57/18/5823},

issn = {0031-9155, 1361-6560},

year  = {2012},

date = {2012-09-01},

journal = {PHYSICS IN MEDICINE AND BIOLOGY},

volume = {57},

number = {18},

pages = {5823–5840},

abstract = {MRI-guided prostate biopsy in conventional closed-bore scanners requires transferring the patient outside the bore during needle insertion due to the constrained in-bore space, causing a safety hazard and limiting image feedback. To address this issue, we present our custom-made in-bore setup and software to support MRI-guided transperineal prostate biopsy in a wide-bore 3 T MRI scanner. The setup consists of a specially designed tabletop and a needle-guiding template with a Z-frame that gives a physician access to the perineum of the patient at the imaging position and allows the physician to perform MRI-guided transperineal biopsy without moving the patient out of the scanner. The software and Z-frame allow registration of the template, target planning and biopsy guidance. Initially, we performed phantom experiments to assess the accuracy of template registration and needle placement in a controlled environment. Subsequently, we embarked on our clinical trial (N = 10). The phantom experiments showed that the translational errors of the template registration along the right-left (RP) and anterior-posterior (AP) axes were 1.1 +/- 0.8 and 1.4 +/- 1.1 mm, respectively, while the rotational errors around the RL, AP and superior-inferior axes were (0.8 +/- 1.0)degrees, (1.7 +/- 1.6)degrees and (0.0 +/- 0.0)degrees, respectively. The 2D root-mean-square (RMS) needle-placement error was 3 mm. The clinical biopsy procedures were safely carried out in all ten clinical cases with a needle-placement error of 5.4 mm (2D RMS). In conclusion, transperineal prostate biopsy in a wide-bore 3T scanner is feasible using our custom-made tabletop setup and software, which supports manual needle placement without moving the patient out of the magnet.},

note = {Num Pages: 18 

Place: Bristol 

Publisher: IoP Publishing Ltd 

Web of Science ID: WOS:000308859500010},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kosa_mri_2012,

title = {MRI driven magnetic microswimmers},

author = {Gabor Kosa and Peter Jakab and Gabor Szekely and Nobuhiko Hata},

doi = {10.1007/s10544-011-9594-7},

issn = {1387-2176, 1572-8781},

year  = {2012},

date = {2012-02-01},

journal = {BIOMEDICAL MICRODEVICES},

volume = {14},

number = {1},

pages = {165–178},

abstract = {Capsule endoscopy is a promising technique for diagnosing diseases in the digestive system. Here we design and characterize a miniature swimming mechanism that uses the magnetic fields of the MRI for both propulsion and wireless powering of the capsule. Our method uses both the static and the radio frequency (RF) magnetic fields inherently available in MRI to generate a propulsive force. Our study focuses on the evaluation of the propulsive force for different swimming tails and experimental estimation of the parameters that influence its magnitude. We have found that an approximately 20 mm long, 5 mm wide swimming tail is capable of producing 0.21 mN propulsive force in water when driven by a 20 Hz signal providing 0.85 mW power and the tail located within the homogeneous field of a 3 T MRI scanner. We also analyze the parallel operation of the swimming mechanism and the scanner imaging. We characterize the size of artifacts caused by the propulsion system. We show that while the magnetic micro swimmer is propelling the capsule endoscope, the operator can locate the capsule on the image of an interventional scene without being obscured by significant artifacts. Although this swimming method does not scale down favorably, the high magnetic field of the MRI allows self propulsion speed on the order of several millimeter per second and can propel an endoscopic capsule in the stomach.},

note = {Num Pages: 14 

Place: Dordrecht 

Publisher: Springer 

Web of Science ID: WOS:000300851600015},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{jayender_optimal_2011,

title = {Optimal transseptal puncture location for robot-assisted left atrial catheter ablation},

author = {J. Jayender and R. V. Patel and G. F. Michaud and N. Hata},

doi = {10.1002/rcs.388},

issn = {1478-5951},

year  = {2011},

date = {2011-06-01},

journal = {INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY},

volume = {7},

number = {2},

pages = {193–201},

abstract = {Background The preferred method of treatment for atrial fibrillation (AF) is by catheter ablation, in which a catheter is guided into the left atrium through a transseptal puncture. However, the transseptal puncture constrains the catheter, thereby limiting its manoeuvrability and increasing the difficulty in reaching various locations in the left atrium. In this paper, we address the problem of choosing the optimal transseptal puncture location for performing cardiac ablation to obtain maximum manoeuvrability of the catheter. Methods We have employed an optimization algorithm to maximize the global isotropy index (GII) to evaluate the optimal transseptal puncture location. As part of this algorithm, a novel kinematic model for the catheter has been developed, based on a continuum robot model. Pre-operative MR/CT images of the heart are segmented using the open source image-guided therapy software, 3D Slicer, to obtain models of the left atrium and septal wall. These models are input to the optimization algorithm to evaluate the optimal transseptal puncture location. Results The continuum robot model accurately describes the kinematics of the catheter. Simulation and experimental results for the optimal transseptal puncture location are presented in this paper. The optimization algorithm generates discrete points on the septal wall for which the dexterity of the catheter in the left atrium is maximum, corresponding to a GII of 0.4362. Conclusion We have developed an optimization algorithm based on the GII to evaluate the optimal position of the transseptal puncture for left atrial cardiac ablation. Copyright (C) 2011 John Wiley & Sons, Ltd.},

note = {Num Pages: 9 

Place: Malden 

Publisher: Wiley-Blackwell 

Web of Science ID: WOS:000291596100011},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{tokuda_impact_2011,

title = {Impact of Nonrigid Motion Correction Technique on Pixel-Wise Pharmacokinetic Analysis of Free-Breathing Pulmonary Dynamic Contrast-Enhanced MR Imaging},

author = {Junichi Tokuda and Hatsuho Mamata and Ritu R. Gill and Nobuhiko Hata and Ron Kikinis and Robert F. Padera and Robert E. Lenkinski and David J. Sugarbaker and Hiroto Hatabu},

doi = {10.1002/jmri.22490},

issn = {1053-1807},

year  = {2011},

date = {2011-04-01},

journal = {JOURNAL OF MAGNETIC RESONANCE IMAGING},

volume = {33},

number = {4},

pages = {968–973},

abstract = {Purpose: To investigates the impact of nonrigid motion correction on pixel-wise pharmacokinetic analysis of free-breathing DCE-MRI in patients with solitary pulmonary nodules (SPNs). Misalignment of focal lesions due to respiratory motion in free-breathing dynamic contrast-enhanced MRI (DCE-MRI) precludes obtaining reliable time-intensity curves, which are crucial for pharmacokinetic analysis for tissue characterization. Materials and Methods: Single-slice 2D DCE-MRI was obtained in 15 patients. Misalignments of SPNs were corrected using nonrigid B-spline image registration. Pixel-wise pharmacokinetic parameters K(trans), v(e), and k(ep) were estimated from both original and motion-corrected DCE-MRI by fitting the two-compartment pharmacokinetic model to the time-intensity curve obtained in each pixel. The "goodness-of-fit" was tested with chi(2)-test in pixel-by-pixel basis to evaluate the reliability of the parameters. The percentages of reliable pixels within the SPNs were compared between the original and motion-corrected DCE-MRI. In addition, the parameters obtained from benign and malignant SPNs were compared. Results: The percentage of reliable pixels in the motion-corrected DCE-MRI was significantly larger than the original DCE-MRI (P = 4 x 10(-7)). Both K(trans) and k(ep) derived from the motion-corrected DCE-MRI showed significant differences between benign and malignant SPNs (P = 0.024, 0.015). Conclusion: The study demonstrated the impact of nonrigid motion correction technique on pixel-wise pharmacokinetic analysis of free-breathing DCE-MRI in SPNs.},

note = {Num Pages: 6 

Place: Malden 

Publisher: Wiley-Blackwell 

Web of Science ID: WOS:000288913200027},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{elhawary_intraoperative_2011,

title = {Intraoperative Real-Time Querying of White Matter Tracts During Frameless Stereotactic Neuronavigation},

author = {Haytham Elhawary and Haiying Liu and Pratik Patel and Isaiah Norton and Laura Rigolo and Xenophon Papademetris and Nobuhiko Hata and Alexandra J. Golby},

doi = {10.1227/NEU.0b013e3182036282},

issn = {0148-396X, 1524-4040},

year  = {2011},

date = {2011-02-01},

journal = {NEUROSURGERY},

volume = {68},

number = {2},

pages = {506–516},

abstract = {BACKGROUND: Brain surgery faces important challenges when trying to achieve maximum tumor resection while avoiding postoperative neurological deficits. OBJECTIVE: For surgeons to have optimal intraoperative information concerning white matter (WM) anatomy, we developed a platform that allows the intraoperative real-time querying of tractography data sets during frameless stereotactic neuronavigation. METHODS: Structural magnetic resonance imaging, functional magnetic resonance imaging, and diffusion tensor imaging were performed on 5 patients before they underwent lesion resection using neuronavigation. During the procedure, the tracked surgical tool tip position was transferred from the navigation system to the 3-dimensional Slicer software package, which used this position to seed the WM tracts around the tool tip location, rendering a geometric visualization of these tracts on the preoperative images previously loaded onto the navigation system. The clinical feasibility of this approach was evaluated in 5 cases of lesion resection. In addition, system performance was evaluated by measuring the latency between surgical tool tracking and visualization of the seeded WM tracts. RESULTS: Lesion resection was performed successfully in all 5 patients. The seeded WM tracts close to the lesion and other critical structures, as defined by the functional and structural images, were interactively visualized during the intervention to determine their spatial relationships relative to the lesion and critical cortical areas. Latency between tracking and visualization of tracts was less than a second for a fiducial radius size of 4 to 5 mm. CONCLUSION: Interactive tractography can provide an intuitive way to inspect critical WM tracts in the vicinity of the surgical region, allowing the surgeon to have increased intraoperative WM information to execute the planned surgical resection.},

note = {Num Pages: 11 

Place: Cary 

Publisher: Oxford Univ Press Inc 

Web of Science ID: WOS:000285994300087},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid22003598,

title = {Distance measurement in middle ear surgery using a telemanipulator},

author = {Thomas Maier and Gero Strauss and Franz Bauer and Andreas Grasser and Nobuhiko Hata and Tim C Lueth},

doi = {10.1007/978-3-642-23623-5_6},

year  = {2011},

date = {2011-01-01},

journal = {Med Image Comput Comput Assist Interv},

volume = {14},

number = {Pt 1},

pages = {41--48},

abstract = {In this article, a new tool for the intraoperative measurement of distances within the middle ear by means of a micromanipulator is presented. The purpose of this work was to offer the surgeon a highly accurate tool for measuring the distances between two points in the 3D operational field. The tool can be useful in various operations; this article focuses, however, on measuring the distance between the stapes footplate and the long process of the incus of the middle ear. This distance is important for estimating the proper prosthesis length in stapedotomy for treating otosclerosis. We evaluated the system using a simplified mechanical model. Our results show that the system can measure distances with a maximum error of 0.04 mm.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid21335868,

title = {High-field MRI-compatible needle placement robot for prostate interventions},

author = {Hao Su and Alex Camilo and Gregory A Cole and Nobuhiko Hata and Clare M Tempany and Gregory S Fischer},

issn = {0926-9630},

year  = {2011},

date = {2011-01-01},

journal = {Stud Health Technol Inform},

volume = {163},

pages = {623--629},

abstract = {This paper presents the design of a magnetic resonance imaging (MRI) compatible needle placement system actuated by piezoelectric actuators for prostate brachytherapy and biopsy. An MRI-compatible modular 3 degree-of-freedom (DOF) needle driver module coupled with a 3-DOF x-y-z stage is proposed as a slave robot to precisely deliver radioactive brachytherapy seeds under interactive MRI guidance. The needle driver module provides for needle cannula rotation, needle insertion and cannula retraction to enable the brachytherapy procedure with the preloaded needles. The device mimics the manual physician gesture by two point grasping (hub and base) and provides direct force measurement of needle insertion force by fiber optic force sensors. The fabricated prototype is presented and an experiment with phantom trials in 3T MRI is analyzed to demonstrate the system compatibility.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{oguro_image_2011,

title = {Image registration of pre-procedural MRI and intra-procedural CT images to aid CT-guided percutaneous cryoablation of renal tumors},

author = {Sota Oguro and Kemal Tuncali and Haytham Elhawary and Paul R. Morrison and Nobuhiko Hata and Stuart G. Silverman},

doi = {10.1007/s11548-010-0485-9},

issn = {1861-6410, 1861-6429},

year  = {2011},

date = {2011-01-01},

journal = {INTERNATIONAL JOURNAL OF COMPUTER ASSISTED RADIOLOGY AND SURGERY},

volume = {6},

number = {1},

pages = {111–117},

abstract = {Purpose To determine whether a non-rigid registration (NRR) technique was more accurate than a rigid registration (RR) technique when fusing pre-procedural contrast-enhanced MR images to unenhanced CT images during CT-guided percutaneous cryoablation of renal tumors. Methods Both RR and NRR were applied retrospectively to 11 CT-guided percutaneous cryoablation procedures performed to treat renal tumors (mean diameter; 23 mm). Pre-procedural contrast-enhanced MR images of the upper abdomen were registered to unenhanced intra-procedural CT images obtained just prior to the ablation. RRs were performed manually, and NRRs were performed using an intensity-based approach with affine and Basis-Spline techniques used for modeling displacement. Registration accuracy for each technique was assessed using the 95% Hausdorff distance (HD), Fiducial Registration Error (FRE) and the Dice Similarity Coefficient (DSC). Statistical differences were analyzed using a two-sided Student's t-test. Time for each registration technique was recorded. Results Mean 95% HD (1.7 mm), FRE (1.7 mm) and DSC (0.96) using the NRR technique were significantly better than mean 95% HD (6.4 mm), FRE (5.0 mm) and DSC (0.88) using the RR technique (P < 0.05 for each analysis). Mean registration times of NRR and RR techniques were 15.2 and 5.7 min, respectively. Conclusions The non-rigid registration technique was more accurate than the rigid registration technique when fusing pre-procedural MR images to intra-procedural unenhanced CT images. The non-rigid registration technique can be used to improve visualization of renal tumors during CT-guided cryoablation procedures.},

note = {Num Pages: 7 

Place: Heidelberg 

Publisher: Springer Heidelberg 

Web of Science ID: WOS:000289291700011},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid20817574,

title = {Multimodality non-rigid image registration for planning, targeting and monitoring during CT-guided percutaneous liver tumor cryoablation},

author = {Haytham Elhawary and Sota Oguro and Kemal Tuncali and Paul R Morrison and Servet Tatli and Paul B Shyn and Stuart G Silverman and Nobuhiko Hata},

doi = {10.1016/j.acra.2010.06.004},

issn = {1878-4046},

year  = {2010},

date = {2010-11-01},

journal = {Acad Radiol},

volume = {17},

number = {11},

pages = {1334--1344},

abstract = {RATIONALE AND OBJECTIVES: The aim of this study was to develop non-rigid image registration between preprocedure contrast-enhanced magnetic resonance (MR) images and intraprocedure unenhanced computed tomographic (CT) images, to enhance tumor visualization and localization during CT imaging-guided liver tumor cryoablation procedures.nnMATERIALS AND METHODS: A non-rigid registration technique was evaluated with different preprocessing steps and algorithm parameters and compared to a standard rigid registration approach. The Dice similarity coefficient, target registration error, 95th-percentile Hausdorff distance, and total registration time (minutes) were compared using a two-sided Student's t test. The entire registration method was then applied during five CT imaging-guided liver cryoablation cases with the intraprocedural CT data transmitted directly from the CT scanner, with both accuracy and registration time evaluated.nnRESULTS: Selected optimal parameters for registration were a section thickness of 5 mm, cropping the field of view to 66% of its original size, manual segmentation of the liver, B-spline control grid of 5 × 5 × 5, and spatial sampling of 50,000 pixels. A mean 95th-percentile Hausdorff distance of 3.3 mm (a 2.5 times improvement compared to rigid registration, P < .05), a mean Dice similarity coefficient of 0.97 (a 13% increase), and a mean target registration error of 4.1 mm (a 2.7 times reduction) were measured. During the cryoablation procedure, registration between the preprocedure MR and the planning intraprocedure CT imaging took a mean time of 10.6 minutes, MR to targeting CT image took 4 minutes, and MR to monitoring CT imaging took 4.3 minutes. Mean registration accuracy was <3.4 mm.nnCONCLUSIONS: Non-rigid registration allowed improved visualization of the tumor during interventional planning, targeting, and evaluation of tumor coverage by the ice ball. Future work is focused on reducing segmentation time to make the method more clinically acceptable.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid21132087,

title = {Preliminary Evaluation of a MRI-compatible Modular Robotic System for MRI-guided Prostate Interventions},

author = {Sang-Eun Song and Nathan Cho and Junichi Tokuda and Nobuhiko Hata and Clare Tempany and Gabor Fichtinger and Iulian Iordachita},

doi = {10.1109/BIOROB.2010.5626987},

issn = {2155-1774},

year  = {2010},

date = {2010-09-01},

journal = {Proc IEEE RAS EMBS Int Conf Biomed Robot Biomechatron},

volume = {2010},

pages = {796--801},

abstract = {Magnetic Resonance Imaging (MRI) guided robotic interventions have been introduced in order to advance prostate cancer detection and treatment. To overcome problems of such robotic interventions, we have been developing a pneumatically actuated MRI-compatible modular robotic system for MRI-guided transperineal prostate intervention and its interventional procedure. For system evaluation, a series of experiments have been conducted and this paper reports a needle insertion experiment using prostate phantom and patient mockup trials. The needle insertion experiment resulted in noticeable consistent error in one direction, which we will investigate further. Nonetheless, patient mockup experiences suggest that the modular robotic system and its interventional procedure are well integrated and implemented in clinical environment.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{arata_open_2010,

title = {Open core control software for surgical robots},

author = {Jumpei Arata and Hiroaki Kozuka and Hyung Wook Kim and Naoyuki Takesue and B. Vladimirov and Masamichi Sakaguchi and Junichi Tokuda and Nobuhiko Hata and Kiyoyuki Chinzei and Hideo Fujimoto},

doi = {10.1007/s11548-009-0388-9},

issn = {1861-6410, 1861-6429},

year  = {2010},

date = {2010-05-01},

journal = {INTERNATIONAL JOURNAL OF COMPUTER ASSISTED RADIOLOGY AND SURGERY},

volume = {5},

number = {3},

pages = {211–220},

abstract = {Object In these days, patients and doctors in operation room are surrounded by many medical devices as resulting from recent advancement of medical technology. However, these cutting-edge medical devices are working independently and not collaborating with each other, even though the collaborations between these devices such as navigation systems and medical imaging devices are becoming very important for accomplishing complex surgical tasks (such as a tumor removal procedure while checking the tumor location in neurosurgery). On the other hand, several surgical robots have been commercialized, and are becoming common. However, these surgical robots are not open for collaborations with external medical devices in these days. Acutting-edge "intelligent surgical robot" will be possible in collaborating with surgical robots, various kinds of sensors, navigation system and so on. On the other hand, most of the academic software developments for surgical robots are "home-made" in their research institutions and not open to the public. Therefore, open source control software for surgical robots can be beneficial in this field. From these perspectives, we developed Open Core Control software for surgical robots to overcome these challenges. Materials and methods In general, control softwares have hardware dependencies based on actuators, sensors and various kinds of internal devices. Therefore, these control softwares cannot be used on different types of robots without modifications. However, the structure of the Open Core Control software can be reused for various types of robots by abstracting hardware dependent parts. In addition, network connectivity is crucial for collaboration between advanced medical devices. The OpenIGTLink is adopted in Interface class which plays a role to communicate with external medical devices. At the same time, it is essential to maintain the stable operation within the asynchronous data transactions through network. In the Open Core Control software, several techniques for this purpose were introduced. Virtual fixture is well known technique as a "force guide" for supporting operators to perform precise manipulation by using a master-slave robot. The virtual fixture for precise and safety surgery was implemented on the system to demonstrate an idea of high-level collaboration between a surgical robot and a navigation system. The extension of virtual fixture is not a part of the Open Core Control system, however, the function such as virtual fixture cannot be realized without a tight collaboration between cutting-edge medical devices. By using the virtual fixture, operators can pre-define an accessible area on the navigation system, and the area information can be transferred to the robot. In this manner, the surgical console generates the reflection force when the operator tries to get out from the pre-defined accessible area during surgery. Results The Open Core Control software was implemented on a surgical master-slave robot and stable operation was observed in a motion test. The tip of the surgical robot was displayed on a navigation system by connecting the surgical robot with a 3D position sensor through the OpenIGTLink. The accessible area was pre-defined before the operation, and the virtual fixture was displayed as a "force guide" on the surgical console. In addition, the system showed stable performance in a duration test with network disturbance. Conclusion In this paper, a design of the Open Core Control software for surgical robots and the implementation of virtual fixture were described. The Open Core Control software was implemented on a surgical robot system and showed stable performance in high-level collaboration works. The Open Core Control software is developed to be a widely used platform of surgical robots. Safety issues are essential for control software of these complex medical devices. It is important to follow the global specifications such as a FDA requirement "General Principles of Software Validation" or IEC62304. For following these regulations, it is important to develop a self-test environment. Therefore, a test environment is now under development to test various interference in operation room such as a noise of electric knife by considering safety and test environment regulations such as ISO13849 and IEC60508. The Open Core Control software is currently being developed software in open-source manner and available on the Internet. A communization of software interface is becoming a major trend in this field. Based on this perspective, the Open Core Control software can be expected to bring contributions in this field.},

note = {Num Pages: 10 

Place: Heidelberg 

Publisher: Springer Heidelberg 

Web of Science ID: WOS:000289288800002},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid19699057,

title = {Integrated navigation and control software system for MRI-guided robotic prostate interventions},

author = {Junichi Tokuda and Gregory S Fischer and Simon P DiMaio and David G Gobbi and Csaba Csoma and Philip W Mewes and Gabor Fichtinger and Clare M Tempany and Nobuhiko Hata},

doi = {10.1016/j.compmedimag.2009.07.004},

issn = {1879-0771},

year  = {2010},

date = {2010-01-01},

journal = {Comput Med Imaging Graph},

volume = {34},

number = {1},

pages = {3--8},

abstract = {A software system to provide intuitive navigation for MRI-guided robotic transperineal prostate therapy is presented. In the system, the robot control unit, the MRI scanner, and the open-source navigation software are connected together via Ethernet to exchange commands, coordinates, and images using an open network communication protocol, OpenIGTLink. The system has six states called "workphases" that provide the necessary synchronization of all components during each stage of the clinical workflow, and the user interface guides the operator linearly through these workphases. On top of this framework, the software provides the following features for needle guidance: interactive target planning; 3D image visualization with current needle position; treatment monitoring through real-time MR images of needle trajectories in the prostate. These features are supported by calibration of robot and image coordinates by fiducial-based registration. Performance tests show that the registration error of the system was 2.6mm within the prostate volume. Registered real-time 2D images were displayed 1.97 s after the image location is specified.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{tokuda_integrated_2010,

title = {Integrated navigation and control software system for MRI-guided robotic prostate interventions},

author = {Junichi Tokuda and Gregory S. Fischer and Simon P. DiMaio and David G. Gobbi and Csaba Csoma and Philip W. Mewes and Gabor Fichtinger and Clare M. Tempany and Nobuhiko Hata},

doi = {10.1016/j.compmedimag.2009.07.004},

issn = {0895-6111, 1879-0771},

year  = {2010},

date = {2010-01-01},

journal = {COMPUTERIZED MEDICAL IMAGING AND GRAPHICS},

volume = {34},

number = {1},

pages = {3–8},

abstract = {A software system to provide intuitive navigation for MRI-guided robotic transperineal prostate therapy is presented. In the system, the robot control unit, the MRI scanner, and the open-source navigation software are connected together via Ethernet to exchange commands, coordinates, and images using an open network communication protocol, OpenIGTLink. The system has six states called "workphases" that provide the necessary synchronization of all components during each stage of the clinical workflow, and the user interface guides the operator linearly through these workphases. On top of this framework, the software provides the following features for needle guidance: interactive target planning; 3D image visualization with current needle position; treatment monitoring through real-time MR images of needle trajectories in the prostate. These features are supported by calibration of robot and image coordinates by fiducial-based registration. Performance tests show that the registration error of the system was 2.6 mm within the prostate volume. Registered real-time 2D images were displayed 1.97 s after the image location is specified. (C) 2009 Elsevier Ltd. All rights reserved.},

note = {Num Pages: 6 

Place: Oxford 

Publisher: Pergamon-Elsevier Science Ltd 

Web of Science ID: WOS:000274449900002},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{tokuda_openigtlink_2009,

title = {OpenIGTLink: an open network protocol for image-guided therapy environment},

author = {Junichi Tokuda and Gregory S. Fischer and Xenophon Papademetris and Ziv Yaniv and Luis Ibanez and Patrick Cheng and Haiying Liu and Jack Blevins and Jumpei Arata and Alexandra J. Golby and Tina Kapur and Steve Pieper and Everette C. Burdette and Gabor Fichtinger and Clare M. Tempany and Nobuhiko Hata},

doi = {10.1002/rcs.274},

issn = {1478-5951},

year  = {2009},

date = {2009-12-01},

journal = {INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY},

volume = {5},

number = {4},

pages = {423–434},

abstract = {Background With increasing research on system integration for image-guided therapy (IGT), there has been a strong demand for standardized communication among devices and software to share data such as target positions, images and device status. Method We propose a new, open, simple and extensible network communication protocol for IGT, named OpenIGTLink, to transfer transform, image and status messages. We conducted performance tests and use-case evaluations in five clinical and engineering scenarios. Results The protocol was able to transfer position data with submillisecond latency up to 1024 fps and images with latency of <10 ms at 32 fps. The use-case tests demonstrated that the protocol is feasible for integrating devices and software. Conclusion The protocol proved capable of handling data required in the IGT setting with sufficient time resolution and latency. The protocol not only improves the interoperability of devices and software but also promotes transitions of research prototypes to clinical applications. Copyright (C) 2009 John Wiley & Sons, Ltd.},

note = {Num Pages: 12 

Place: Hoboken 

Publisher: John Wiley & Sons Inc 

Web of Science ID: WOS:000272877200009},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid19856437,

title = {MRI signal intensity based B-spline nonrigid registration for pre- and intraoperative imaging during prostate brachytherapy},

author = {Sota Oguro and Junichi Tokuda and Haytham Elhawary and Steven Haker and Ron Kikinis and Clare M C Tempany and Nobuhiko Hata},

doi = {10.1002/jmri.21955},

issn = {1522-2586},

year  = {2009},

date = {2009-11-01},

journal = {J Magn Reson Imaging},

volume = {30},

number = {5},

pages = {1052--1058},

abstract = {PURPOSE: To apply an intensity-based nonrigid registration algorithm to MRI-guided prostate brachytherapy clinical data and to assess its accuracy.nnMATERIALS AND METHODS: A nonrigid registration of preoperative MRI to intraoperative MRI images was carried out in 16 cases using a Basis-Spline algorithm in a retrospective manner. The registration was assessed qualitatively by experts' visual inspection and quantitatively by measuring the Dice similarity coefficient (DSC) for total gland (TG), central gland (CG), and peripheral zone (PZ), the mutual information (MI) metric, and the fiducial registration error (FRE) between corresponding anatomical landmarks for both the nonrigid and a rigid registration method.nnRESULTS: All 16 cases were successfully registered in less than 5 min. After the nonrigid registration, DSC values for TG, CG, PZ were 0.91, 0.89, 0.79, respectively, the MI metric was -0.19 +/- 0.07 and FRE presented a value of 2.3 +/- 1.8 mm. All the metrics were significantly better than in the case of rigid registration, as determined by one-sided t-tests.nnCONCLUSION: The intensity-based nonrigid registration method using clinical data was demonstrated to be feasible and showed statistically improved metrics when compare to only rigid registration. The method is a valuable tool to integrate pre- and intraoperative images for brachytherapy.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{morikawa_preliminary_2009,

title = {Preliminary clinical experiences of a motorized manipulator for magnetic resonance image-guided microwave coagulation therapy of liver tumors},

author = {Shigehiro Morikawa and Shigeyuki Naka and Koichiro Murakami and Yoshimasa Kurumi and Hisanori Shiomi and Tohru Tani and Hasnine A. Haque and Junichi Tokuda and Nobuhiko Hata and Toshiro Inubushi},

doi = {10.1016/j.amjsurg.2009.02.006},

issn = {0002-9610},

year  = {2009},

date = {2009-09-01},

journal = {AMERICAN JOURNAL OF SURGERY},

volume = {198},

number = {3},

pages = {340–347},

abstract = {BACKGROUND: In magnetic resonance (MR) image-guided microwave thermocoagulation of liver tumors, the choice of the optimal puncture route is an important and time-consuming process. To assist this process, we have developed a motorized MR-compatible manipulator. METHODS: The manipulator consists of a passive end effecter with 2 degrees-of-freedom (DOF) rotation and active base stages with 3 ultrasonic motors. It automatically chases the preset target point with synergetic remote-center-of-motion (RCM) control. A mechanical torque limiter and an electrical shutdown switch were added for patient safety. RESULTS: The manipulator was used for this procedure in 15 cases and successfully utilized to treat liver tumors in various locations. Thoracoscopic assistance was combined with the manipulator in 6 cases. No complications were experienced. CONCLUSIONS: The manipulator was found to be very effective for assisting MR-guided microwave coagulation of liver tumors. (C) 2009 Elsevier Inc. All rights reserved.},

note = {Num Pages: 8 

Place: Bridgewater 

Publisher: Excerpta Medica Inc-Elsevier Science Inc 

Web of Science ID: WOS:000270440800007},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{golland_advances_2009,

title = {Advances in Radiological Image Analysis from MICCAI 2007. (vol 15, pg 1345, 2008)},

author = {Polina Golland and Nobuhiko Hata and Sebastien Ourselin and Nicholas Ayache},

issn = {1076-6332},

year  = {2009},

date = {2009-03-01},

journal = {ACADEMIC RADIOLOGY},

volume = {16},

number = {3},

pages = {331–331},

note = {Num Pages: 1 

Place: New York 

Publisher: Elsevier Science Inc 

Web of Science ID: WOS:000263390500011},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{tokuda_lung_2009,

title = {Lung Motion and Volume Measurement by Dynamic 3D MRI Using a 128-Channel Receiver Coil},

author = {Junichi Tokuda and Melanie Schmitt and Yanping Sun and Samuel Patz and Yi Tang and Carolyn E. Mountford and Nobuhiko Hata and Lawrence L. Wald and Hiroto Hatabu},

doi = {10.1016/j.acra.2008.07.021},

issn = {1076-6332, 1878-4046},

year  = {2009},

date = {2009-01-01},

journal = {ACADEMIC RADIOLOGY},

volume = {16},

number = {1},

pages = {22–27},

abstract = {Rationale and Objectives. The authors present their initial experience using a 3-T whole-body scanner equipped with a 128-channel coil applied to lung motion assessment. Recent improvements in fast magnetic resonance imaging (MRI) technology have enabled several trials of free-breathing three-dimensional (313) imaging of the lung. A large number of image frames necessarily increases the difficulty of image analysis and therefore warrants automatic image processing. However, the intensity homogeneities of images of prior dynamic 3D lung MRI studies have been insufficient to use such methods. In this study, initial data were obtained at 3 T with a 128-channel coil that demonstrate the feasibility of acquiring multiple sets of 3D pulmonary scans during free breathing and that have sufficient quality to be amenable to automatic segmentation. Materials and Methods. Dynamic 3D images of the lungs of two Volunteers were acquired with acquisition times of 0.62 to 0.76 frames/s and an image matrix of 128 X 128, with 24 to 30 slice encodings. The volunteers were instructed to take shallow and deep breaths during the scans. The variation Of lung volume was measured from the segmented images. Results. Dynamic 3D images were successfully acquired for both respiratory conditions for each subject. The images showed whole-lung motion, including lifting of the chest wall and the displacement of the diaphragm, with sufficient contrast to distinguish these structures from adjacent tissues. The average time to complete segmentation for one 3D image was 4.8 seconds. The tidal volume measured was consistent with known tidal volumes for healthy subjects performing deep-breathing maneuvers. The temporal resolution was insufficient to measure tidal volumes for shallow breathing Conclusion. This initial experience with a 3-T whole-body scanner and a 128-channel coil showed that the scanner and imaging protocol provided dynamic 3D images with spatial and temporal resolution sufficient to delineate the diaphragmatic domes and chest wall during active breathing. In addition, the intensity homogeneities and signal-to-noise ratio were adequate to perform automatic segmentation.},

note = {Num Pages: 6 

Place: New York 

Publisher: Elsevier Science Inc 

Web of Science ID: WOS:000262021600004},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{xia_integrated_2008,

title = {An integrated system for planning, navigation and robotic assistance for skull base surgery},

author = {Tian Xia and Clint Baird and George Jallo and Kathryn Hayes and Nobuyuki Nakajima and Nobuhiko Hata and Peter Kazanzides},

doi = {10.1002/rcs.213},

issn = {1478-5951, 1478-596X},

year  = {2008},

date = {2008-12-01},

journal = {INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY},

volume = {4},

number = {4},

pages = {321–330},

abstract = {Background We developed an image-guided robot system to provide mechanical assistance for skull base drilling, which is performed to gain access for some neurosurgical interventions, such as tumour resection. The motivation for introducing this robot was to improve safety by preventing the surgeon from accidentally damaging critical neurovascular structures during the drilling procedure. Methods We integrated a Stealthstation (R) navigation system, a NeuroMate (R) robotic arm with a six-degree-of-freedom force sensor, and the 3D Slicer visualization software to allow the robotic arm to be used in a navigated, cooperatively-controlled fashion by the surgeon. We employed virtual fixtures to constrain the motion of the robot-held cutting tool, so that it remained in the safe zone that was defined on a preoperative CT scan. Results We performed experiments on both foam skull and cadaver heads. The results for foam blocks cut using different registrations yielded an average placement error of 0.6 mm and an average dimensional error of 0.6 mm. We drilled the posterior porus acusticus in three cadaver heads and concluded that the robot-assisted procedure is clinically feasible and provides some ergonomic benefits, such as stabilizing the drill. We obtained postoperative CT scans of the cadaver heads to assess the accuracy and found that some bone outside the virtual fixture boundary was cut. The typical overcut was 1-2 mm, with a maximum overcut of about 3 mm. Conclusions The image-guided cooperatively-controlled robot system can improve the safety and ergonomics of skull base drilling by stabilizing the drill and enforcing virtual fixtures to protect critical neurovascular structures. The next step is to improve the accuracy so that the overcut can be reduced to a more clinically acceptable value of about 1 mm. Copyright (C) 2008 John Wiley & Sons, Ltd.},

note = {Num Pages: 10 

Place: Hoboken 

Publisher: Wiley 

Web of Science ID: WOS:000262013900005},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{fischer_mri-compatible_2008,

title = {MRI-compatible pneumatic robot for transperineal prostate needle placement},

author = {Gregory S. Fischer and Iulian Iordachita and Csaba Csoma and Junichi Tokuda and Simon P. DiMaio and Clare M. Tempany and Nobuhiko Hata and Gabor Fichtinger},

doi = {10.1109/TMECH.2008.924044},

issn = {1083-4435, 1941-014X},

year  = {2008},

date = {2008-06-01},

journal = {IEEE-ASME TRANSACTIONS ON MECHATRONICS},

volume = {13},

number = {3},

pages = {295–305},

abstract = {Magnetic resonance imaging (MRI) can provide high-quality 3-D visualization of prostate and surrounding tissue, thus granting potential to be a superior medical imaging modality for guiding and monitoring prostatic interventions. However, the benefits cannot be readily harnessed for interventional procedures due to difficulties that surround the use of high-field (1.5T or greater) MRI. The inability to use conventional mechatronics and the confined physical space makes it extremely challenging to access the patient. We have designed a robotic assistant system that overcomes these difficulties and promises safe and reliable intraprostatic needle placement inside closed high-field MRI scanners. MRI compatibility of the robot has been evaluated under 3T MRI using standard prostate imaging sequences and average SNR loss is limited to 5%. Needle alignment accuracy of the robot under servo pneumatic control is better than 0.94 mm rms per axis. The complete system workflow has been evaluated in phantom studies with accurate visualization and targeting of five out of five I cm targets. The paper explains the robot mechanism and controller design, the system integration, and presents results of preliminary evaluation of the system.},

note = {Num Pages: 11 

Place: Piscataway 

Publisher: Ieee-Inst Electrical Electronics Engineers Inc 

Web of Science ID: WOS:000256966700005},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid21686038,

title = {Pneumatically Operated MRI-Compatible Needle Placement Robot for Prostate Interventions},

author = {Gregory S Fischer and Iulian Iordachita and Csaba Csoma and Junichi Tokuda and Philip W Mewes and Clare M Tempany and Nobuhiko Hata and Gabor Fichtinger},

doi = {10.1109/ROBOT.2008.4543587},

issn = {2152-4092},

year  = {2008},

date = {2008-06-01},

journal = {IEEE Int Conf Robot Autom},

volume = {2008},

pages = {2489--2495},

abstract = {Magnetic Resonance Imaging (MRI) has potential to be a superior medical imaging modality for guiding and monitoring prostatic interventions. The strong magnetic field prevents the use of conventional mechatronics and the confined physical space makes it extremely challenging to access the patient. We have designed a robotic assistant system that overcomes these difficulties and promises safe and reliable intra-prostatic needle placement inside closed high-field MRI scanners. The robot performs needle insertion under real-time 3T MR image guidance; workspace requirements, MR compatibility, and workflow have been evaluated on phantoms. The paper explains the robot mechanism and controller design and presents results of preliminary evaluation of the system.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{hata_mri-compatible_2008,

title = {MRI-compatible manipulator with remote-center-of-motion control},

author = {Nobuhiko Hata and Junichi Tokuda and Shelley Hurwitz and Shigehiro Morikawa},

doi = {10.1002/jmri.21314},

issn = {1053-1807, 1522-2586},

year  = {2008},

date = {2008-05-01},

journal = {JOURNAL OF MAGNETIC RESONANCE IMAGING},

volume = {27},

number = {5},

pages = {1130–1138},

abstract = {Purpose: To develop and assess a needle-guiding manipulator for MRI-guided therapy that allows a physician to freely select the needle insertion path while maintaining remote center of motion (RCM) at the tumor site. Materials and Methods: The manipulator consists of a three-degrees-of-freedom (DOF) base stage and passive needle holder with unconstrained two-DOF rotation. The synergistic control keeps the Virtual RCM at the preplanned target using encoder outputs from the needle holder as input to motorize the base stage. Results: The manipulator assists in searching for an optimal needle insertion path which is a complex and time-consuming task in MRI-guided ablation therapy for liver tumors. The assessment study showed that accuracy of keeping the virtual RCM to predefined position is 3.0 mm. In a phantom test, the physicians found the needle insertion path faster with than without the manipulator (number of physicians = 3},

note = {Num Pages: 9 

Place: Hoboken 

Publisher: Wiley-Blackwell 

Web of Science ID: WOS:000255622700025},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{richolt_quantitative_2008,

title = {Quantitative Evaluation of Angular Measurements on Plain Radiographs in Patients With Slipped Capital Femoral Epiphysis A 3-Dimensional Analysis of Computed Tomography-Based Computer Models of 46 Femora},

author = {Jens A. Richolt and Nobuhiko Hata and Ron Kikinis and Detlef Scale and Michael B. Millis},

doi = {10.1097/BPO.0b013e318168c7b0},

issn = {0271-6798},

year  = {2008},

date = {2008-05-01},

journal = {JOURNAL OF PEDIATRIC ORTHOPAEDICS},

volume = {28},

number = {3},

pages = {291–296},

abstract = {Background: In cases of slipped capital femoral epiphyses (SCFE) findings on plain radiographs help to determine the further necessary course of action. In severe cases possible surgical procedures are commonly indicated and planned using angular measurements on plain radiographs to describe the extent and direction of the slip. The aim of this study was to quantify the amount of angular errors deriving from this method. Methods: Data and imaging of 23 consecutive patients with SCFE ( 31 affected and 15 unaffected femora) were included in this study. We determined shaft-neck/shaft-physis angles on antero-posterior and torsional angles on lateral radiographs in a clinical setting. As a reference we enabled similar angular measurements on CT-based three-dimensional computer models of the same femora bearing no projectional errors and malpositioning problems. Results: In average, shaft-neck- and shaft-physis-angles were overestimated (6.5 degrees and 10.1 degrees) on plain radiographs and neck torsion underestimated (-15.7 degrees). In general the variability was high, especially for neck and physeal torsional measurements with standard deviations of +/- 11.8 degrees and +/- 16.7 degrees. Three out of four torsional measurements on affected femora were outside a +/- 10 degrees window of error, about every third outside a +/- 20 degrees window. Conclusion: Our results suggest to be careful when using plain radiographs as a source to determine the slippage extent in SCFE. Before using a plain radiograph to reject or indicate and plan a correction osteotomy in an individual case of SCFE the surgeon should reassure that radiographic method and patient positioning provide a reproducible and accurate depiction of the femoral geometry. Level of Evidence: Level II; 23 consecutive patients with SCFE in the senior authors practice; evaluation of the reliability of angular measurements on plain radiographs; CT based 3D computer models of the same femora as a reference.},

note = {Num Pages: 6 

Place: Philadelphia 

Publisher: Lippincott Williams & Wilkins 

Web of Science ID: WOS:000262286000003},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{tempany_mr-guided_2008,

title = {MR-guided prostate interventions},

author = {Clare Tempany and Sarah Straus and Nobuhiko Hata and Steven Haker},

doi = {10.1002/jmri.21259},

issn = {1053-1807, 1522-2586},

year  = {2008},

date = {2008-02-01},

journal = {JOURNAL OF MAGNETIC RESONANCE IMAGING},

volume = {27},

number = {2},

pages = {356–367},

abstract = {In this article the current issues of diagnosis and detection of prostate cancer are reviewed. The limitations for current techniques are highlighted and some possible solutions with MR imaging and MR-guided biopsy approaches are reviewed. There are several different biopsy approaches under investigation. These include transperineal open magnet approaches to closed-bore 1.5T transrectal biopsies. The imaging, image processing, and tracking methods are also discussed. In the arena of therapy, MR guidance has been used in conjunction with radiation methods, either brachytherapy or external delivery. The principles of the radiation treatment, the toxicities, and use of images are outlined. The future role of imaging and image-guided interventions lie with providing a noninvasive surrogate for cancer surveillance or monitoring treatment response. The shift to minimally invasive focal therapies has already begun and will be very exciting when MR-guided focused ultrasound surgery reaches its full potential.},

note = {Num Pages: 12 

Place: Hoboken 

Publisher: Wiley 

Web of Science ID: WOS:000252909100012},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{hong_real-time_2008,

title = {Real-time magnetic resonance imaging driven by electromagnetic locator for interventional procedure and endoscopic therapy},

author = {Jaesung Hong and Nobuhiko Hata and Kozo Konishi and Makoto Hashizume},

doi = {10.1007/s00464-007-9633-x},

issn = {0930-2794, 1432-2218},

year  = {2008},

date = {2008-02-01},

journal = {SURGICAL ENDOSCOPY AND OTHER INTERVENTIONAL TECHNIQUES},

volume = {22},

number = {2},

pages = {552–556},

abstract = {Background Surgical navigation systems using an optical position sensor have the occlusion problem due to a person or instrument in the line of sight of the camera. In this study, occlusion-free real-time magnetic resonance (MR) scanning with a passive electromagnetic locator is proposed. Methods A newly developed converter transforms the data of an electromagnetic locator into that of an optical sensor. Registration between the two different coordinate systems is performed for the electromagnetic locator to substitute the optical sensor without modifying the MRI system. Results An oil marker attached to the electromagnetic locator was identified in real-time MR images. Preliminary results demonstrated the high usability of the electromagnetic locator as an alternative position tracking method in the MR gantry. Conclusions The occlusion problem of optical sensors is resolved by the proposed method.},

note = {Num Pages: 5 

Place: New York 

Publisher: Springer 

Web of Science ID: WOS:000252996700048},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid18982666,

title = {Software strategy for robotic transperineal prostate therapy in closed-bore MRI},

author = {Junichi Tokuda and Gregory S Fischer and Csaba Csoma and Simon P DiMaio and David G Gobbi and Gabor Fichtinger and Clare M Tempany and Nobuhiko Hata},

doi = {10.1007/978-3-540-85990-1_84},

year  = {2008},

date = {2008-01-01},

journal = {Med Image Comput Comput Assist Interv},

volume = {11},

number = {Pt 2},

pages = {701--709},

abstract = {A software strategy to provide intuitive navigation for MRI-guided robotic transperineal prostate therapy is presented. In the system, the robot control unit, the MRI scanner, and open-source navigation software are connected to one another via Ethernet to exchange commands, coordinates, and images. Six states of the system called "workphases" are defined based on the clinical scenario to synchronize behaviors of all components. The wizard-style user interface allows easy following of the clinical workflow. On top of this framework, the software provides features for intuitive needle guidance: interactive target planning; 3D image visualization with current needle position; treatment monitoring through real-time MRI. These features are supported by calibration of robot and image coordinates by the fiducial-based registration. The performance test shows that the registration error of the system was 2.6 mm in the prostate area, and it displayed real-time 2D image 1.7 s after the completion of image acquisition.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid18391286,

title = {A cooperatively-controlled image guided robot system for skull base surgery},

author = {Peter Kazanzides and Tian Xia and Clint Baird and George Jallo and Kathryn Hayes and Nobuyuki Nakajima and Nobuhiko Hata},

issn = {0926-9630},

year  = {2008},

date = {2008-01-01},

journal = {Stud Health Technol Inform},

volume = {132},

pages = {198--203},

abstract = {We created an image-guided robot system to assist with skull base drilling by integrating a robot, a commercial navigation system, and an open source visualization platform. The objective of this procedure is to create a cavity in the skull base to allow access for neurosurgical interventions. The motivation for introducing an image-guided robot is to improve safety by preventing the surgeon from accidentally damaging critical structures during the drilling procedure. Our approach is to attach the cutting tool to the robot end-effector and operate the robot in a cooperative control mode, where robot motion is determined from the forces and torques applied by the surgeon. We employ "virtual fixtures" to constrain the motion of the cutting tool so that it remains in the safe zone that was defined on a preoperative CT scan. This paper presents the system design and the results of phantom and cadaveric experiments. Both experiments have demonstrated the feasibility of the system, with average overcut error at about 1 mm and maximum errors at 2.5 mm.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{lesniak_device_2007,

title = {A device guidance method for organ motion compensation in MRI-guided therapy},

author = {Jan Lesniak and Junichi Tokuda and Ron Kikinis and Catherina Burghart and Nobuhiko Hata},

doi = {10.1088/0031-9155/52/21/006},

issn = {0031-9155, 1361-6560},

year  = {2007},

date = {2007-11-01},

journal = {PHYSICS IN MEDICINE AND BIOLOGY},

volume = {52},

number = {21},

pages = {6427–6438},

abstract = {Organ motion compensation in image-guided therapy is an active area of research. However, there has been little research on motion tracking and compensation in magnetic resonance imaging (MRI)-guided therapy. In this paper, we present a method to track a moving organ in MRI and control an active mechanical device for motion compensation. The method proposed is based on MRI navigator echo tracking enhanced by Kalman filtering for noise robustness. We also developed an extrapolation scheme to resolve any discrepancies between tracking and device control sampling rates. The algorithm was tested in a simulation study using a phantom and an active mechanical tool holder. We found that the method is feasible to use in a clinical MRI scanner with sufficient accuracy (0.36 mm to 1.51 mm depending on the range of phantom motion) and is robust to noise. The method proposed may be useful in MRI-guided targeted therapy, such as focused ultrasound therapy for a moving organ.},

note = {Num Pages: 12 

Place: Bristol 

Publisher: IoP Publishing Ltd 

Web of Science ID: WOS:000250443500006},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{sporring_miccai_2007,

title = {Miccai},

author = {Jon Sporring and Nobuhiko Hata},

doi = {10.1080/10929080701752718},

issn = {1092-9088, 1097-0150},

year  = {2007},

date = {2007-11-01},

journal = {COMPUTER AIDED SURGERY},

volume = {12},

number = {6},

pages = {309–310},

note = {Num Pages: 2 

Place: Abingdon 

Publisher: Taylor & Francis Ltd 

Web of Science ID: WOS:000256165000001},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{blumenfeld_transperineal_2007,

title = {Transperineal prostate biopsy under magnetic resonance image guidance: A needle placement accuracy study},

author = {Philip Blumenfeld and Nobuhiko Hata and Simon DiMaio and Kelly Zou and Steven Haker and Gabor Fichtinger and Clare M. C. Tempany},

doi = {10.1002/jmri.21067},

issn = {1053-1807, 1522-2586},

year  = {2007},

date = {2007-09-01},

journal = {JOURNAL OF MAGNETIC RESONANCE IMAGING},

volume = {26},

number = {3},

pages = {688–694},

abstract = {Purpose: To quantify needle placement accuracy of magnetic resonance image (MRI)-guided core needle biopsy of the prostate. Materials and Methods: A total of 10 biopsies were performed with 18-gauge (G) core biopsy needle via a percutaneous transperineal approach. Needle placement error was assessed by comparing the coordinates of preplanned targets with the needle tip measured from the intraprocedural coherent gradient echo images. The source of these errors was subsequently investigated by measuring displacement caused by needle deflection and needle susceptibility artifact shift in controlled phantom studies. Needle placement error due to misalignment of the needle template guide was also evaluated. Results: The mean and standard deviation (SD) of errors in targeted biopsies was 6.5 +/- 3.5 mm. Phantom experiments showed significant placement error due to needle deflection with a needle with an asymmetrically beveled tip (3.2-8.7 mm depending on tissue type) but significantly smaller error with a symmetrical bevel (0.6-1.1 mm). Needle susceptibility artifacts observed a shift of 1.6 +/- 0.4 mm from the true needle axis. Misalignment of the needle template guide contributed an error of 1.5 +/- 0.3 mm. Conclusion: Needle placement error was clinically significant in MRI-guided biopsy for diagnosis of prostate cancer. Needle placement error due to needle deflection was the most significant cause of error, especially for needles with an asymmetrical bevel.},

note = {Num Pages: 7 

Place: Hoboken 

Publisher: Wiley 

Web of Science ID: WOS:000249257300029},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{honda_dynamic_2007,

title = {Dynamic imaging of swallowing in a seated position using open-configuration MRI},

author = {Yasutoshi Honda and Nobuhiko Hata},

doi = {10.1002/jmri.20992},

issn = {1053-1807, 1522-2586},

year  = {2007},

date = {2007-07-01},

journal = {JOURNAL OF MAGNETIC RESONANCE IMAGING},

volume = {26},

number = {1},

pages = {172–176},

abstract = {Purpose: To assess the feasibility of dynamic MRI of swallowing in a seated position using an open-configuration MRI scanner, and to compare its capacity for motion analysis around the pharyngeal wall with that of videofluorography. Materials and Methods: Six healthy individuals (four women and two men, mean age = 31.4 +/- 7.5 years) were examined with an open-configuration MRI system using a fast spoiled gradient-recalled echo (SPGR) sequence. Dynamic imaging was performed while the subjects were in a seated position after they swallowed oral contrast medium from a cup. An oral and maxillofacial radiologist measured the motion of six structures: the hyoid bone (HB), larynx (LX), upper oropharynx (UOP), lower oropharynx (LOP), pharyngoesophageal segment (PES) behind the vocal folds, and upper esophagus (ESO). The measured motions were compared with reported values from videofluorography-based observations. Results: Open-configuration MRI depicted the anatomic structures related to swallowing (lip, tongue, soft palate, mandible, pharynx, HB, LX, and PES), and the course of the mylohyoid muscle (MM). The vertical and anteroposterior displacements of these structures did not differ significantly from those measured by videofluorography. Conclusion: Dynamic imaging of swallowing using open-configuration MRI provides image information comparable to that obtained from videofluorography. key Words: dynamic magnetic resonance imaging; swallowing function; seated position; posterior pharyngeal wall; videofluorography.},

note = {Num Pages: 5 

Place: Hoboken 

Publisher: Wiley 

Web of Science ID: WOS:000248644500025},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid17659564,

title = {Dynamic imaging of swallowing in a seated position using open-configuration MRI},

author = {Yasutoshi Honda and Nobuhiko Hata},

doi = {10.1002/jmri.20992},

issn = {1053-1807},

year  = {2007},

date = {2007-07-01},

journal = {J Magn Reson Imaging},

volume = {26},

number = {1},

pages = {172--176},

abstract = {PURPOSE: To assess the feasibility of dynamic MRI of swallowing in a seated position using an open-configuration MRI scanner, and to compare its capacity for motion analysis around the pharyngeal wall with that of videofluorography.nnMATERIALS AND METHODS: Six healthy individuals (four women and two men, mean age = 31.4 +/- 7.5 years) were examined with an open-configuration MRI system using a fast spoiled gradient-recalled echo (SPGR) sequence. Dynamic imaging was performed while the subjects were in a seated position after they swallowed oral contrast medium from a cup. An oral and maxillofacial radiologist measured the motion of six structures: the hyoid bone (HB), larynx (LX), upper oropharynx (UOP), lower oropharynx (LOP), pharyngoesophageal segment (PES) behind the vocal folds, and upper esophagus (ESO). The measured motions were compared with reported values from videofluorography-based observations.nnRESULTS: Open-configuration MRI depicted the anatomic structures related to swallowing (lip, tongue, soft palate, mandible, pharynx, HB, LX, and PES), and the course of the mylohyoid muscle (MM). The vertical and anteroposterior displacements of these structures did not differ significantly from those measured by videofluorography.nnCONCLUSION: Dynamic imaging of swallowing using open-configuration MRI provides image information comparable to that obtained from videofluorography.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{dimaio_robot-assisted_2007,

title = {Robot-assisted needle placement in open MRI: System architecture, integration and validation},

author = {S. P. Dimaio and S. Pieper and K. Chinzei and N. Hata and S. J. Haker and D. F. Kacher and G. Fichtinger and C. M. Tempany and R. Kikins},

doi = {10.1080/10929080601168254},

issn = {1092-9088, 1097-0150},

year  = {2007},

date = {2007-01-01},

journal = {COMPUTER AIDED SURGERY},

volume = {12},

number = {1},

pages = {15–24},

abstract = {In prostate cancer treatment, there is a move toward targeted interventions for biopsy and therapy, which has precipitated the need for precise image-guided methods for needle placement. This paper describes an integrated system for planning and performing percutaneous procedures with robotic assistance under MRI guidance. A graphical planning interface allows the physician to specify the set of desired needle trajectories, based on anatomical structures and lesions observed in the patient's registered pre-operative and pre-procedural MR images, immediately prior to the intervention in an open-bore MRI scanner. All image-space coordinates are automatically computed, and are used to position a needle guide by means of an MRI-compatible robotic manipulator, thus avoiding the limitations of the traditional fixed needle template. Automatic alignment of real-time intra-operative images aids visualization of the needle as it is manually inserted through the guide. Results from in-scanner phantom experiments are provided.},

note = {Conference Name: 14th Conference on Medicine Meets Virtual Reality 

Num Pages: 10 

Place: Abingdon 

Publisher: Taylor & Francis Ltd 

Web of Science ID: WOS:000256027800003},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nakajima_surface_2007,

title = {Surface rendering-based virtual intraventricular endoscopy: Retrospective feasibility study and comparison to volume rendering-based approach},

author = {Nobuyuki Nakajima and Jun Wada and Tamotsu Miki and Jo Haraoka and Nobuhiko Hata},

doi = {10.1016/j.neuroimage.2007.04.023},

issn = {1053-8119, 1095-9572},

year  = {2007},

date = {2007-01-01},

journal = {NEUROIMAGE},

volume = {37},

pages = {S89–S99},

abstract = {Objective: Virtual endoscopic simulations using volume rendering (VR) have been proposed as a tool for training and understanding intraventricular anatomy. It is not known whether surface rendering (SR), an alternative to VR, can visualize intraventricular and subependymal structures better and thus making the virtual endoscope more useful for simulating the intraventricular endoscopy. We sought to develop SR-virtual endoscopy and compared the visibility of anatomical structures in SR and VR using retrospective cases. Materials and methods: Fourteen patients who underwent endoscopic intraventricular surgery of third ventricle enrolled the study. SR-virtual endoscopy module was developed in open-source software 3D Slicer and virtual endoscopic scenes from the retrospective cases were created. VR virtual endoscopy of the same cases was prepared in commercial software. Three neurosurgeons scored the visibility of substructures in lateral and third ventricle, arteries, cranial nerves, and other lesions Results: We found that VR and SR-virtual endoscopy performed similarly in visualization of substructures in lateral and third ventricle (not significant statistically). However, the SR was statistically significantly better in visualizing subependymal arteries, cranial nerves, and other lesions (p < 0.05, respectively). Conclusions: We concluded that SR-virtual endoscopy is a promising tool to visualize critical anatomical structures in simulated endoscopic intraventricular surgery. The results lead us to propose a hybrid technique of volume and surface rendering to balance the strength of surface rendering alone in visualizing arteries, nerves and lesions, with fast volume rendering of third and lateral ventricles. (c) 2007 Elsevier Inc. All rights reserved.},

note = {Num Pages: 11 

Place: San Diego 

Publisher: Academic Press Inc Elsevier Science 

Web of Science ID: WOS:000249434100009},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid18051095,

title = {Application of open source image guided therapy software in MR-guided therapies},

author = {Nobuhiko Hata and Steve Piper and Ferenc A Jolesz and Clare M C Tempany and Peter McL Black and Shigehiro Morikawa and Horoshi Iseki and Makoto Hashizume and Ron Kikinis},

doi = {10.1007/978-3-540-75757-3_60},

year  = {2007},

date = {2007-01-01},

journal = {Med Image Comput Comput Assist Interv},

volume = {10},

number = {Pt 1},

pages = {491--498},

abstract = {We present software engineering methods to provide free open-source software for MR-guided therapy. We report that graphical representation of the surgical tools, interconnectively with the tracking device, patient-to-image registration, and MRI-based thermal mapping are crucial components of MR-guided therapy in sharing such software. Software process includes a network-based distribution mechanism by multi-platform compiling tool CMake, CVS, quality assurance software DART. We developed six procedures in four separate clinical sites using proposed software engineering and process, and found the proposed method is feasible to facilitate multicenter clinical trial of MR-guided therapies. Our future studies include use of the software in non-MR-guided therapies.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid17644360,

title = {Challenges in image-guided therapy system design},

author = {Simon Dimaio and Tina Kapur and Kevin Cleary and Stephen Aylward and Peter Kazanzides and Kirby Vosburgh and Randy Ellis and James Duncan and Keyvan Farahani and Heinz Lemke and Terry Peters and William Bill Lorensen and David Gobbi and John Haller and Laurence Larry Clarke and Stephen Pizer and Russell Taylor and Robert Galloway and Gabor Fichtinger and Nobuhiko Hata and Kimberly Lawson and Clare Tempany and Ron Kikinis and Ferenc Jolesz},

doi = {10.1016/j.neuroimage.2007.04.026},

issn = {1053-8119},

year  = {2007},

date = {2007-01-01},

journal = {Neuroimage},

volume = {37 Suppl 1},

number = {0 1},

pages = {S144--S151},

abstract = {System development for image-guided therapy (IGT), or image-guided interventions (IGI), continues to be an area of active interest across academic and industry groups. This is an emerging field that is growing rapidly: major academic institutions and medical device manufacturers have produced IGT technologies that are in routine clinical use, dozens of high-impact publications are published in well regarded journals each year, and several small companies have successfully commercialized sophisticated IGT systems. In meetings between IGT investigators over the last two years, a consensus has emerged that several key areas must be addressed collaboratively by the community to reach the next level of impact and efficiency in IGT research and development to improve patient care. These meetings culminated in a two-day workshop that brought together several academic and industrial leaders in the field today. The goals of the workshop were to identify gaps in the engineering infrastructure available to IGT researchers, develop the role of research funding agencies and the recently established US-based National Center for Image Guided Therapy (NCIGT), and ultimately to facilitate the transfer of technology among research centers that are sponsored by the National Institutes of Health (NIH). Workshop discussions spanned many of the current challenges in the development and deployment of new IGT systems. Key challenges were identified in a number of areas, including: validation standards; workflows, use-cases, and application requirements; component reusability; and device interface standards. This report elaborates on these key points and proposes research challenges that are to be addressed by a joint effort between academic, industry, and NIH participants.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{dimaio_image-guided_2006,

title = {Image-guided neurosurgery at Brigham and Women's Hospital - The integration of imaging, navigation, and interventional devices},

author = {Simon P. DiMaio and Neculai Archip and Nobuhiko Hata and Ion-Florin Talos and Simon K. Warfield and Amit Majumdar and Nathan McDannold and Kullervo Hynynen and Paul R. Morrison and William M. Wells and Daniel F. Kacher and Randy E. Ellis and Alexandra J. Golby and Peter M. Black and Ferenc A. Jolesz and Ron Kikinis},

doi = {10.1109/MEMB.2006.1705749},

issn = {0739-5175, 1937-4186},

year  = {2006},

date = {2006-10-01},

journal = {IEEE ENGINEERING IN MEDICINE AND BIOLOGY MAGAZINE},

volume = {25},

number = {5},

pages = {67–73},

note = {Num Pages: 7 

Place: Piscataway 

Publisher: Ieee-Inst Electrical Electronics Engineers Inc 

Web of Science ID: WOS:000240674500014},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid17020201,

title = {Image-guided neurosurgery at Brigham and Women's Hospital},

author = {Simon P Dimaio and Neculai Archip and Nobuhiko Hata and Ion-Florin Talos and Simon K Warfield and Amit Majumdar and Nathan Mcdannold and Kullervo Hynynen and Paul R Morrison and William M Wells and Daniel F Kacher and Randy E Ellis and Alexandra J Golby and Peter M Black and Ferenc A Jolesz and Ron Kikinis},

doi = {10.1109/memb.2006.1705749},

issn = {0739-5175},

year  = {2006},

date = {2006-01-01},

journal = {IEEE Eng Med Biol Mag},

volume = {25},

number = {5},

pages = {67--73},

keywords = {},

pubstate = {published},

tppubtype = {article}

}