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Tiernan J. D. Byrnes, Thomas R. Barrick, B. Anthony Bell, and Chris A. Clark

or radiotherapy planning. Diffusion tensor imaging is an imaging technique that is sensitive to the diffusion of water in brain tissue in vivo. 6 The direction in which water diffusion is greatest, as derived from the DT of each image voxel, reflects the mean longitudinal direction of axons through the white matter of the brain. 35 This information can then be used to delineate cerebral white matter pathways by applying tractography algorithms. 7 , 14 , 22 , 29 These tractography algorithms reconstruct 3D streamlines by iteratively following the direction of

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Daniel T. Ginat, Sanjay P. Prabhu, and Joseph R. Madsen

follow-up to the CT scans show diffuse thickening and dorsal scalloping of the body of the corpus callosum (arrows) , with associated low T1 and high T2 signals in a transverse orientation. Cystic areas are present within the posterior body of the corpus callosum (arrowheads) . F ig . 3. There is elevated diffusivity, and decreased FA within the corpus callosum is shown on the ADC (A) and FA (B) maps, respectively. Superior (C) and side (D) view tractography images with B0 (nondiffusion basis) overlay show the corpus callosum white matter tracts

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Vejay N. Vakharia, Sjoerd B. Vos, Gavin P. Winston, Matthew J. Gutman, Victoria Wykes, Andrew W. McEvoy, Anna Miserocchi, Rachel Sparks, Sebastien Ourselin, and John S. Duncan

%–100% of patients. 14–16 In contemporary series of transsylvian approaches, VFDs are large enough to preclude 66% of patients from retaining a driving license when considered with postoperative seizure freedom. 17 , 18 In contrast, modified ATLR techniques that incorporate temporobasal approaches to the temporal horn have shown VFD rates as low as 4%, 19 highlighting the importance of the surgical approach. Previous studies have shown the benefits of OR tractography for identifying Meyer’s loop. 20–22 These studies have shown considerable variation in the anterior

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Vejay N. Vakharia, Sjoerd B. Vos, Gavin P. Winston, Matthew J. Gutman, Victoria Wykes, Andrew W. McEvoy, Anna Miserocchi, Rachel Sparks, Sebastien Ourselin, and John S. Duncan

%–100% of patients. 14–16 In contemporary series of transsylvian approaches, VFDs are large enough to preclude 66% of patients from retaining a driving license when considered with postoperative seizure freedom. 17 , 18 In contrast, modified ATLR techniques that incorporate temporobasal approaches to the temporal horn have shown VFD rates as low as 4%, 19 highlighting the importance of the surgical approach. Previous studies have shown the benefits of OR tractography for identifying Meyer’s loop. 20–22 These studies have shown considerable variation in the anterior

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Cormac G. Gavin and H. Ian Sabin

focused on using separately acquired tractography images and fusing them with stereotactic treatment images in order to analyze dosimetry to critical fiber tracts and improve treatment planning. 11 , 12 , 13 This process has also been recently reported using other radiosurgical platforms. 5 , 16 The use of diffusion tensor imaging (DTI) has been reported to reduce the risk of motor complications after radiosurgery. 9 We present our method of integrating stereotactic DTI tractography into conventional treatment planning for GKRS. Methods Twenty patients who underwent

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Kyousuke Kamada, Tomoki Todo, Takahiro Ota, Kenji Ino, Yoshitaka Masutani, Shigeki Aoki, Fumiya Takeuchi, Kensuke Kawai, and Nobuhito Saito

them to identify the eloquent fibers accurately and to safely achieve maximal resection of brain lesions. Although the procedure enabled preservation of the eloquent functions, technical difficulties have remained, such as determination of optimal stimulus conditions, the patient's cooperation, and certain risks related to anesthesia. Diffusion tensor imaging–based tractography is a recently established technique that holds promise in the visualization of white matter connections. The principle of DT imaging is to measure changes in the MR signal with diffusion

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Kyousuke Kamada, Tomoki Todo, Yoshitaka Masutani, Shigeki Aoki, Kenji Ino, Tetsuya Takano, Takaaki Kirino, Nobutaka Kawahara, and Akio Morita

. 4, 9 Recently developed fiber-tracking processes (tractography) demonstrate the major axonal fascicles of interest by calculating DT and measuring changes in the nuclear MR signal with diffusion sensitization along at least six noncolinear directions. 1 Many groups have used DT imaging—based tractography to visualize the spatial relationship between lesions adjacent to the sensorimotor system and the CST for presurgical planning and functional prediction. 11, 15, 16, 18 Note, however, that it is technically difficult to integrate DT imaging—based tractography

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Matthew Muir, Ron Gadot, Sarah Prinsloo, Hayley Michener, Jeffrey Traylor, Prazwal Athukuri, Sudhakar Tummala, Vinodh A. Kumar, and Sujit S. Prabhu

-making. 1 Transcranial magnetic stimulation (TMS) and functional MRI (fMRI) are noninvasive imaging modalities that can functionally identify the primary motor cortex. These techniques can also be combined with diffusion tensor imaging (DTI) tractography to visualize subcortical motor fibers. 2 – 8 Patients at our institution with perirolandic tumors undergo both TMS and fMRI preoperatively. Each technique often yields markedly different representations of the primary motor cortex. Despite the use of sophisticated preoperative imaging along with intraoperative

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Vance T. Lehman, Kendall H. Lee, Bryan T. Klassen, Daniel J. Blezek, Abhinav Goyal, Bhavya R. Shah, Krzysztof R. Gorny, John Huston III, and Timothy J. Kaufmann

using anatomical landmarks with target adjustment based on patient response to initial subablative sonications. Development of reliable imaging-based direct methods to target the VIM has been desirable, given the uncertainty of the VIM location, potential for adverse effects, and need for adjustments. Indeed, there are other potential methods to identify or infer the location of thalamic nuclei, including the use of advanced MR pulse sequences and white matter tractography. Of these possibilities, tractography has so far emerged as the most promising for clinical use

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João Gabriel Ribeiro Gomes, Alessandra Augusta Gorgulho, Amanda de Oliveira López, Crystian Wilian Chagas Saraiva, Lucas Petri Damiani, Anderson Martins Pássaro, João Victor Salvajoli, Ludmila de Oliveira Siqueira, Bernardo Peres Salvajoli, and Antônio Afonso Ferreira De Salles

example, preexisting vasculopathy, previous surgery, and previous irradiation are believed to be risk factors. Actually, the patients with these comorbidities, at risk from conventional surgery, are chosen for radiosurgery. 11 , 20 Specifically for these patients, it is important to reduce complications with additional strategies and enhance safety with a proper definition of the regions at risk. Diffusion tensor imaging (DTI) tractography reconstruction of the pyramidal tract based on anisotropy is increasingly being used in stereotactic functional surgery