Function connectivity MRI to evaluate the changes of the motorial nerve net in patients with brain tumors adjacent to the central sulcus occurred with reorganization of motor function

Objective: We investigated the changes of the motorial network in patients suffered from brain tumors adjacent to the central sulcus occurred with reorganization of motor function using function connectivity MRI (fcMRI) technique in order to provide the new evidence for the compensational hypothesis of the reorganization caused by focal lesions. Methods: Using 1.5 T MRI unit, 14 patients with brain tumors in the vicinity of the central sulcus occurred with reorganization of motor function and 6 normal volunteers were examined with fcMRI technique while the subjects performed no task. By selecting seed voxels (region of interest) in the regions showing the most activation in Mi area on the activated map and cross correlating with every, voxel within the brain, the fcMRI maps based on unilateral primary motor (M1) area were calculated. The location, extent and volume of the region showing significant connectivity to the several seed voxel, such as left/right M1 area in the health group and affected/unaffected Mlarea in the patient group were evaluated on the fcMRI map. Results: In healthy group, the extent and volume of the region showing significant connectivity to the left Mlarea [(9514.17±186.92)mm3] were almost similar to those to the right M1 area [(9364.67±382.75) mm3]. There showed no significant difference in motor connectivity between the two groups (P>0.05). In the tumor group, the volume of regions showing significant connectivity to the M1 area located in the affected hemisphere [(11193.14 ± 811.29) mm3] was obviously higher than that of regions based on the seed voxel in the unaffected side [(6549.86± 400.94) mm3] (t=20.383, P<0.01). The volume was significantly different among the regions showing high connectivity to the M1 of the affected side in patient group, those showing significant connectivity to the left M1 and right M1 in health group (P<0.01), the former was the biggest (P<0.01). The extent of the regions showing connectivity to the affected M1 was consistent with the reorganization area of motor function revealed by fMRI. The volume of regions showing significant connectivity to M1 area of unaffected hemisphere in patient group showed significant difference compared with those showing significant connectivity to the left M1 and right M1 in health group (P<0.01), the former was smallest (LSD, P< 0.01), especially in the affected hemisphere. It might mean the disrupted functional connectivity between the M1 area of unaffected hemisphere in patient group and motor mca located in the collateral side. Conclusion: The increased connectivity between the M1 area of the affected hemisphere and the other motor cortex might indicate that the reorganization in tile motor pathway and the formation of the potential compensatory network second to the impairment of the normal motor pathway resulted in the functional reorganization of the motor cortex. The fcMRI technique might be a valuable approach to reveal the pathophysiological changes of nerve network caused by brain tumor. (authors)