关键词: 磁共振成像, 弥散张量成像, 纤维束成像, 腰骶神经根, 椎间孔

Abstract:

Objective To evaluate the diagnostic value of diffusion tensor imaging (DTI) in lumbosacral nerve root entrapment.Methods Seven patients with back pain and single sciatica and eight healthy volunteers underwent 3T MR imaging. The MR protocol consisted of sagittal T1-and T2-weighted spin echo sequence, followed by an axial T2-weighted spin echo sequence focused on the lumbar disc. In all subjects, DTI was performed with echo-planar imaging and the lumbosacral nerve roots were visualized with fiber tractography. Fractional anisotropy (FA) values in the lumbar nerve roots were quantified on DTI images. Results Respectively, mean FA values of the roots of healthy volunteers was 0.314±0.021 (left L3), 0.305±0.018 (right L3), 0.343±0.055 (left L4), 0.330±0.055 (right L4), 0.347±0.016 (left L5), 0.338±0.028 (right L5), 0.338±0.027 (left S1), 0.343±0.032 (right S1). Statistically significant differences were not found between the left and right side nerve roots at the same lumbosacral segment. In all subjects, the lumbar nerve roots were clearly visualized with fiber tractography. There were nine entrapped roots in seven patients. FA values were lower in entrapped roots than in intact roots. The side of the entrapped roots shown on fiber tractography image was consistent to the symptom, while conventional MR imaging was not. Compared with conventional MR imaging, diffusion tensor imaging fiber tractography was a better tool to evaluate lumbosacral nerve root related to the symptom.

Key words: magnetic resonance imaging, diffusion tensor imaging, fiber tractography, lumbosacral nerve root, intervertebral foramen