Introduction: To investigate the utility of resting-state functional MRI (R-fMRI) in the functional parcellation and localization of SMA in healthy subjects and patients with glioma. The utility of this novel technique in brain tumor surgery around SMA was also assessed
Methods: R-fMRI was acquired from 249 healthy and 8 patients. Defined by AAL template, SMA was parcellated into three subregions according to functional connectivity (FC) patterns based on R-fMRI among healthy subjects. The function of each subregion was characterised by assessing whole-brain FC and meta-analysis of existing functional imaging studies. In areas consist of voxels within and around (2-voxel expansion) SMA, FC was calculated between each voxel and the SMA subregions. SVM was used to discriminate voxels in or outside each subregion. Then, the technique was used to localize the SMA in patients with glioma. The subregions of SMA were precisely stimulated using direct cortical stimulation (DCS) guided by intraoperative MRI when patients doing finger opposition motor tasks during surgery.
Results: The method has successfully parcellated SMA into three subregions, including Pre-, Mid- and Post-SMA. The function of Pre-, Mid- and Post-SMA was supposed to be correlated with conflict, eye movement, and hand movement and coordination respectively. The accuracy of localizing the SMA in the contralateral hemisphere was 87.4% with one-voxel error by 10-fold cross-validation in the healthy subjects. SMA localization was validated in all patients with DCS. Complete surgical resection was achieved in 6 patients and subtotal in 2 patients. In the short-term period, 3 patients experienced postoperative worsening, however, all recovered to normal at 1-month follow-up.
Conclusions: Connectivity-based technique based on R-fMRI is effective to parcellate and localize the SMA. Integration of R-fMRI and DCS is useful to identify and protect the SMA in patient-specific surgery for cerebral glioma around SMA.
Patient Care: Diagnose and predict SMA syndrome after surgery within motor area
Learning Objectives: By the conclusion of this session, participants should be able to: 1) How to perform functional parcellation and localization of SMA in healthy subjects and patients with glioma; 2) Well diagnose the SMA syndrome after brain tumor surgery within eloquent areas.