Diffusion Tensor Imaging of the Corticospinal Tract in Patients with Brain Neoplasms

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Purpose: To maximize the extent of tumor resection and minimize postoperative neurological deficits in patients with brain neoplasms, it is very important to evaluate the integrity of the corticospinal tract (CST) before surgery. We attempted to determine whether CST abnormality in these patients correlates with clinical motor weakness.
Methods: We retrospectively evaluated 19 patients (16 men, 3 women, aged 39 to 70 years) with pathologically proven brain neoplasms with lesions adjacent to the posterior limb of the internal capsule and categorized their motor function as normal or abnormal based on clinical assessment. After correcting raw diffusion tensor image (DTI) data for motion and eddy-current artifacts, we computed fractional anisotropy (FA) and apparent diffusion coefficient (ADC) maps. We manually segmented the CST from the level of the cerebral peduncle to the internal capsule, used the segmented CST as the mask for FA and ADC measurements, and compared normalized FA (nFA) and ADC (nADC) values relative to the contralateral normal side using a 2-tailed, unpaired t-test.
Results: Compared with the normalized values for patients with normal motor function, patients with abnormal motor function demonstrated significantly decreased FA (P<0.001, 0.65±0.09 versus 0.85±0.08) and significantly increased ADC (P<0.01, 1.49±0.17 versus 1.23±0.22).
Conclusion: DTI metrics can be used for preoperative evaluation of the integrity of the CST microstructure.