Motion Tracking and Compensation
Objective
Motion of the organ during intervention is serious issue for image guidance. It causes location descrepancy between a target observed in pre- or intra-operative images and an actual target, since time resolution of intra-operative MR image is not sufficent to track the organ motion due to respiration or cardiac activity of a patient. The objective of this project is to provide a method to track the organ with sub-second order of frame rate by using MR.
Recent Updates
We presented 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.
Publications
- Lesniak J, Tokuda J, Kikinis R, Burghart C and Hata N, A device guidance method for organ motion compensation in MRI-guided therapy, Physics in Medicine and Biology 2007; 52(21):6427-6438
- Tokuda J, Morikawa S, Dohi T, Hata N. Motion tracking in MR-guided liver therapy by using navigator echoes and projection profile matching. Acad Radiol 2004; 11(1):111-20