MR-Guided Brain Laser Ablation
Laser-induced interstitial thermal therapy (LITT) is a minimally invasive surgical technique for the treatment of solid tumors. The technique involves the percutaneous introduction of an optical fiber through a needle; light delivered to the tissue is absorbed proximal to the needle tip and the heat generated creates a localized coagulative necrosis. Unlike an open surgical procedure, the laser-tissue interaction is not visible by the operator, so methods of monitoring and controlling the treatment are needed. One solution has been through the use of radiologic imaging techniques such as magnetic resonance imaging (MRI), which can provide images of the interaction. MRI can provide a non-invasive means by which to monitor LITT, providing near real-time monitoring: it can help perform accurate image-guided placement of the optical fiber(s) into the target and show intra-operative imaging to monitor tissue changes as they occur. Imaging can then provide feedback (i.e. images of acute thermal effects) by which dosimetry can be optimized. Our goal is to develop an ideal research computer workstation to assist in the manipulation of image data and provide needed feedback as to the laser effect during a clinical procedure.
We reported the assembly of hardware and software into a customized system to use MRI to non-invasively monitor laser-induced interstitial thermal therapy of brain tumors. An open-configuration interventional MRI unit was used to guide optical fiber placement and monitor the deposition of laser energy into the targeted lesion. T1-weighted fast spin echo and gradient echo images were used to monitor the laser tissue interaction. The images were transferred from the MRI scanner to a customized research workstation and were processed intra-operatively. Newly developed software enabled rapid (27-221 ms) availability of calculated images. A case report is given showing images that reveal the laser-tissue interaction. The system design is feasible for on-line monitoring of interstitial laser therapy. [Hata 1998]
- Hata N, Morrison PR, Kettenbach J, Kikinis R, Jolesz FA. Computer-Assisted Intra-Operative MRI Monitoring of Interstitial Laser Therapy in the Brain: A Case Report. J Biomed Optics. 1998;3(3):304-11.