Stefan E Poirier1,2, Benjamin Y M Kwan3, Michael T Jurkiewicz4, Lina Samargandy4, David A Steven5,6, Ana Suller-Marti5, Victor Lam Shin Cheung7, Ali R Khan8,4,9, Jonathan Romsa4, Frank S Prato10,8,4, Jorge G Burneo5,6, Jonathan D Thiessen10,8,4, Udunna C Anazodo11,12. 1. Lawson Imaging, Lawson Health Research Institute, 268 Grosvenor St., London, Ontario, N6A 4 V2, Canada. spoirie6@uwo.ca. 2. Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada. spoirie6@uwo.ca. 3. Department of Diagnostic Radiology, Queen's University, Kingston, Ontario, Canada. 4. Department of Medical Imaging, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada. 5. Epilepsy Program, Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada. 6. Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada. 7. Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada. 8. Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada. 9. Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada. 10. Lawson Imaging, Lawson Health Research Institute, 268 Grosvenor St., London, Ontario, N6A 4 V2, Canada. 11. Lawson Imaging, Lawson Health Research Institute, 268 Grosvenor St., London, Ontario, N6A 4 V2, Canada. uanazodo@lawsonimaging.ca. 12. Department of Medical Biophysics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada. uanazodo@lawsonimaging.ca.
Abstract
BACKGROUND: Hybrid PET/MRI can non-invasively improve localization and delineation of the epileptic focus (EF) prior to surgical resection in medically refractory epilepsy (MRE), especially when MRI is negative or equivocal. In this study, we developed a PET-guided diffusion tractography (PET/DTI) approach combining 18F-fluorodeoxyglucose PET (FDG-PET) and diffusion MRI to investigate white matter (WM) integrity in MRI-negative MRE patients and its potential impact on epilepsy surgical planning. METHODS: FDG-PET and diffusion MRI of 14 MRI-negative or equivocal MRE patients were used to retrospectively pilot the PET/DTI approach. We used asymmetry index (AI) mapping of FDG-PET to detect the EF as brain areas showing the largest decrease in FDG uptake between hemispheres. Seed-based WM fiber tracking was performed on DTI images with a seed location in WM 3 mm from the EF. Fiber tractography was repeated in the contralateral brain region (opposite to EF), which served as a control for this study. WM fibers were quantified by calculating the fiber count, mean fractional anisotropy (FA), mean fiber length, and mean cross-section of each fiber bundle. WM integrity was assessed through fiber visualization and by normalizing ipsilateral fiber measurements to contralateral fiber measurements. The added value of PET/DTI in clinical decision-making was evaluated by a senior neurologist. RESULTS: In over 60% of the patient cohort, AI mapping findings were concordant with clinical reports on seizure-onset localization and lateralization. Mean FA, fiber count, and mean fiber length were decreased in 14/14 (100%), 13/14 (93%), and 12/14 (86%) patients, respectively. PET/DTI improved diagnostic confidence in 10/14 (71%) patients and indicated that surgical candidacy be reassessed in 3/6 (50%) patients who had not undergone surgery. CONCLUSIONS: We demonstrate here the utility of AI mapping in detecting the EF based on brain regions showing decreased FDG-PET activity and, when coupled with DTI, could be a powerful tool for detecting EF and assessing WM integrity in MRI-negative epilepsy. PET/DTI could be used to further enhance clinical decision-making in epilepsy surgery.
BACKGROUND: Hybrid PET/MRI can non-invasively improve localization and delineation of the epileptic focus (EF) prior to surgical resection in medically refractory epilepsy (MRE), especially when MRI is negative or equivocal. In this study, we developed a PET-guided diffusion tractography (PET/DTI) approach combining 18F-fluorodeoxyglucose PET (FDG-PET) and diffusion MRI to investigate white matter (WM) integrity in MRI-negative MRE patients and its potential impact on epilepsy surgical planning. METHODS:FDG-PET and diffusion MRI of 14 MRI-negative or equivocal MRE patients were used to retrospectively pilot the PET/DTI approach. We used asymmetry index (AI) mapping of FDG-PET to detect the EF as brain areas showing the largest decrease in FDG uptake between hemispheres. Seed-based WM fiber tracking was performed on DTI images with a seed location in WM 3 mm from the EF. Fiber tractography was repeated in the contralateral brain region (opposite to EF), which served as a control for this study. WM fibers were quantified by calculating the fiber count, mean fractional anisotropy (FA), mean fiber length, and mean cross-section of each fiber bundle. WM integrity was assessed through fiber visualization and by normalizing ipsilateral fiber measurements to contralateral fiber measurements. The added value of PET/DTI in clinical decision-making was evaluated by a senior neurologist. RESULTS: In over 60% of the patient cohort, AI mapping findings were concordant with clinical reports on seizure-onset localization and lateralization. Mean FA, fiber count, and mean fiber length were decreased in 14/14 (100%), 13/14 (93%), and 12/14 (86%) patients, respectively. PET/DTI improved diagnostic confidence in 10/14 (71%) patients and indicated that surgical candidacy be reassessed in 3/6 (50%) patients who had not undergone surgery. CONCLUSIONS: We demonstrate here the utility of AI mapping in detecting the EF based on brain regions showing decreased FDG-PET activity and, when coupled with DTI, could be a powerful tool for detecting EF and assessing WM integrity in MRI-negative epilepsy. PET/DTI could be used to further enhance clinical decision-making in epilepsy surgery.
Authors: Jasmine D Cakmak; Linshan Liu; Stefan E Poirier; Betsy Schaefer; Raju Poolacherla; Amer M Burhan; Priyadharshini Sabesan; Keith St Lawrence; Jean Théberge; Justin W Hicks; Elizabeth Finger; Lena Palaniyappan; Udunna C Anazodo Journal: J Psychiatry Neurosci Date: 2022-06-02 Impact factor: 5.699
Authors: Freimut D Juengling; Frank Wuest; Sanjay Kalra; Federica Agosta; Ralf Schirrmacher; Alexander Thiel; Wolfgang Thaiss; Hans-Peter Müller; Jan Kassubek Journal: Front Neurol Date: 2022-08-17 Impact factor: 4.086