Applicative value of T2 mapping in evaluating lumbosacral nerve root injury induced by lumbosacral disc herniation

Background To alleviate the damage caused by nerve root entrapment mediated by lumbosacral disc herniation (LDH), an imaging method that allows quantitative evaluation of the lumbosacral nerve injury is necessary. Purpose To investigate the diagnostic value of magnetic resonance (MR) T2 mapping in nerve root injury caused by LDH. Material and Methods A total of 70 patients with unilateral sciatic nerve pain and 35 healthy volunteers were divided into three groups: LDH with nerve root entrapment; LDH without nerve root entrapment; and 35 healthy volunteers. All participants underwent 3.0-T MR with T1-weighted (T1W) imaging, T2-weighted (T2W) imaging, and T2-mapping images. T2 was measured and observed with the left and right nerve roots of the L4-S1 segments in healthy volunteers; the differences between the three groups were compared. T2 and the relaxation rate of nerve root injury were analyzed. Results T2 showed significant differences among the three groups (F = 89.494; P = 0.000), receiver operating characteristic curve revealed that the T2 relaxation threshold was 79 ms, the area under curve (AUC) area was 0.86, sensitivity was 0.77, and specificity was 0.74; the T2 relaxation rate was 1.06, the AUC area was 0.88, sensitivity was 0.74, and specificity was 0.85. Conclusion T2 mapping could quantitatively evaluate the nerve root injury with lumbar disc degeneration. Hence, it can be used for the clinical evaluation of nerve root entrapment caused by LDH.