Background MR Tractography enables non-invasive preoperative depiction of language subcortical tracts, which is crucial for the presurgical work-up of brain tumors; however, it cannot evaluate the exact function of the fibers. Purpose A systematic pipeline was developed to combine tractography reconstruction of language fiber bundles, based on anatomical landmarks (Anatomical-T), with language fMRI cortical activations. A fMRI-targeted Tractography (fMRI-T) was thus obtained, depicting the subsets of the anatomical tracts whose endpoints are located inside a fMRI activation. We hypothesized that fMRI-T could provide additional functional information regarding the subcortical structures, better reflecting the eloquent white matter structures identified intraoperatively. Methods Both Anatomical-T and fMRI-T of language fiber tracts were performed on 16 controls and preoperatively on 16 patients with left-hemisphere brain tumors, using a q-ball residual bootstrap algorithm based on High Angular Resolution Diffusion Imaging (HARDI) datasets (b = 3000 s/mm(2); 60 directions); fMRI ROIs were obtained using picture naming, verbal fluency, and auditory verb generation tasks. In healthy controls, normalized MNI atlases of fMRI-T and Anatomical-T were obtained. In patients, the surgical resection of the tumor was pursued by identifying eloquent structures with intraoperative direct electrical stimulation mapping and extending surgery to the functional boundaries. Post-surgical MRI allowed to identify Anatomical-T and fMRI-T non-eloquent portions removed during the procedure. Results MNI Atlases showed that fMRI-T is a subset of Anatomical-T, and that different task-specific fMRI-T involve both shared subsets and task-specific subsets - e.g., verbal fluency fMRI-T strongly involves dorsal frontal tracts, consistently with the phonogical-articulatory features of this task. A quantitative analysis in patients revealed that Anatomical-T removed portions of AF-SLF and IFOF were significantly greater than verbal fluency fMRI-T ones, suggesting that fMRI-T is a more specific approach. In addition, qualitative analyses showed that fMRI-T AF-SLF and IFOF predict the exact functional limits of resection with increased specificity when compared to Anatomical-T counterparts, especially the superior frontal portion of IFOF, in a subcohort of patients. Conclusion These results suggest that performing fMRI-T in addition to the 'classic' Anatomical-T may be useful in a preoperative setting to identify the 'high-risk subsets' that should be spared during the surgical procedure.
fMRI-Targeted High-Angular Resolution Diffusion MR Tractography to Identify Functional Language Tracts in Healthy Controls and Glioma Patients / F. Sanvito, E. Caverzasi, M. Riva, K.M. Jordan, V. Blasi, P. Scifo, A. Iadanza, S.A. Crespi, S. Cirillo, A. Casarotti, A. Leonetti, G. Puglisi, M. Grimaldi, L. Bello, M.L. Gorno-Tempini, R.G. Henry, A. Falini, A. Castellano. - In: FRONTIERS IN NEUROSCIENCE. - ISSN 1662-453X. - 14(2020 Mar 31).
|Titolo:||fMRI-Targeted High-Angular Resolution Diffusion MR Tractography to Identify Functional Language Tracts in Healthy Controls and Glioma Patients|
CASTELLANO, ANTONELLA (Ultimo) (Corresponding)
|Parole Chiave:||:tractography; high angular resolution diffusion imaging; brain tumor; fMRI; task-fMRI; language network; presurgical brain mapping;|
|Settore Scientifico Disciplinare:||Settore MED/27 - Neurochirurgia|
Settore MED/37 - Neuroradiologia
|Data di pubblicazione:||31-mar-2020|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.3389/fnins.2020.00225|
|Appare nelle tipologie:||01 - Articolo su periodico|