Manish Ranjan1,2, Gavin J B Elias1,2, Alexandre Boutet1,3, Jidan Zhong2, Powell Chu2, Jurgen Germann1, Gabriel A Devenyi4,5, M Mallar Chakravarty4,5,6, Alfonso Fasano1,2,7, Kullervo Hynynen8,9,10, Nir Lipsman11,12, Clement Hamani11,12, Walter Kucharczyk1,3, Michael L Schwartz11, Andres M Lozano1,2, Mojgan Hodaie1,2. 1. 1University Health Network, Toronto. 2. 2Krembil Brain Institute, Toronto. 3. 3Joint Department of Medical Imaging, University of Toronto, Ontario. 4. 4Cerebral Imaging Center, Douglas Mental Health University, McGill University; Departments of. 5. 5Psychiatry and. 6. 6Biological and Biomedical Engineering, McGill University, Montreal, Quebec. 7. 7The Edmond J. Safra Program in Parkinson's Disease and Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital, UHN, Division of Neurology, University of Toronto. 8. 8Sunnybrook Research Institute, Sunnybrook Health Sciences Center, University of Toronto. 9. 9Department of Medical Biophysics, University of Toronto. 10. 10Institute of Biomaterials and Biomedical Engineering, University of Toronto. 11. 11Division of Neurosurgery, Sunnybrook Health Sciences Center, University of Toronto; and. 12. 12Hurvitz Brain Sciences Research Program, Sunnybrook Research Institute, Sunnybrook Health Sciences Center, University of Toronto, Ontario, Canada.
Abstract
OBJECTIVE: Tractography-based targeting of the thalamic ventral intermediate nucleus (T-VIM) is a novel method conferring patient-specific selection of VIM coordinates for tremor surgery; however, its accuracy and clinical utility in magnetic resonance imaging-guided focused ultrasound (MRgFUS) thalamotomy compared to conventional indirect targeting has not been specifically addressed. This retrospective study sought to compare the treatment locations and potential adverse effect profiles of T-VIM with indirect targeting in a large cohort of MRgFUS thalamotomy patients. METHODS: T-VIM was performed using diffusion tractography outlining the pyramidal and medial lemniscus tracts in 43 MRgFUS thalamotomy patients. T-VIM coordinates were compared with the indirect treatment coordinates used in the procedure. Thalamotomy lesions were delineated on postoperative T1-weighted images and displaced ("translated") by the anteroposterior and mediolateral difference between T-VIM and treatment coordinates. Both translated and actual lesions were normalized to standard space and subsequently overlaid with areas previously reported to be associated with an increased risk of motor and sensory adverse effects when lesioned during MRgFUS thalamotomy. RESULTS: T-VIM coordinates were 2.18 mm anterior and 1.82 mm medial to the "final" indirect treatment coordinates. Translated lesions lay more squarely within the boundaries of the VIM compared to nontranslated lesions and showed significantly less overlap with areas associated with sensory adverse effects. Translated lesions overlapped less with areas associated with motor adverse effects; however, this difference was not significant. CONCLUSIONS: T-VIM leads to the selection of more anterior and medial coordinates than the conventional indirect methods. Lesions moved toward these anteromedial coordinates avoid areas associated with an increased risk of motor and sensory adverse effects, suggesting that T-VIM may improve clinical outcomes.
OBJECTIVE: Tractography-based targeting of the thalamic ventral intermediate nucleus (T-VIM) is a novel method conferring patient-specific selection of VIM coordinates for tremor surgery; however, its accuracy and clinical utility in magnetic resonance imaging-guided focused ultrasound (MRgFUS) thalamotomy compared to conventional indirect targeting has not been specifically addressed. This retrospective study sought to compare the treatment locations and potential adverse effect profiles of T-VIM with indirect targeting in a large cohort of MRgFUS thalamotomy patients. METHODS: T-VIM was performed using diffusion tractography outlining the pyramidal and medial lemniscus tracts in 43 MRgFUS thalamotomy patients. T-VIM coordinates were compared with the indirect treatment coordinates used in the procedure. Thalamotomy lesions were delineated on postoperative T1-weighted images and displaced ("translated") by the anteroposterior and mediolateral difference between T-VIM and treatment coordinates. Both translated and actual lesions were normalized to standard space and subsequently overlaid with areas previously reported to be associated with an increased risk of motor and sensory adverse effects when lesioned during MRgFUS thalamotomy. RESULTS: T-VIM coordinates were 2.18 mm anterior and 1.82 mm medial to the "final" indirect treatment coordinates. Translated lesions lay more squarely within the boundaries of the VIM compared to nontranslated lesions and showed significantly less overlap with areas associated with sensory adverse effects. Translated lesions overlapped less with areas associated with motor adverse effects; however, this difference was not significant. CONCLUSIONS: T-VIM leads to the selection of more anterior and medial coordinates than the conventional indirect methods. Lesions moved toward these anteromedial coordinates avoid areas associated with an increased risk of motor and sensory adverse effects, suggesting that T-VIM may improve clinical outcomes.
Entities:
Keywords:
AC-PC = anterior commissure–posterior commissure; AP = anteroposterior; DBS = deep brain stimulation; DTI; DWI = diffusion-weighted imaging; M-L = mediolateral; MER = microelectrode recording; ML = medial lemniscus; MRgFUS; MRgFUS = magnetic resonance imaging–guided focused ultrasound; PT = pyramidal tract; Parkinson’s disease; ROI = region of interest; SHSC = Sunnybrook Health Science Centre; T-VIM = tractography-based targeting of the VIM; TWH = Toronto Western Hospital; VIM = ventral intermediate nucleus; Voa = ventro-oralis anterior nucleus; Vop = ventro-oralis posterior nucleus; diffusion tensor imaging; essential tremor; functional neurosurgery; magnetic resonance imaging–guided focused ultrasound; targeting
Authors: Michelle Paff; Alexandre Boutet; Jürgen Germann; Gavin J B Elias; Clement T Chow; Aaron Loh; Walter Kucharczyk; Alfonso Fasano; Michael L Schwartz; Andres M Lozano Journal: Neurol Clin Pract Date: 2021-08
Authors: Jason H Su; Eun Young Choi; Thomas Tourdias; Manojkumar Saranathan; Casey H Halpern; Jaimie M Henderson; Kim Butts Pauly; Pejman Ghanouni; Brian K Rutt Journal: Hum Brain Mapp Date: 2020-08-06 Impact factor: 5.038