Fig. 4　Tractography before and after microendoscopic surgery for disc herniation and correlation between DTI parameters and symptoms.(A, B) Tractography before and after microendoscopic surgery for L5/S1 disc herniation. A: Before surgery, a right S1 nerve disruption is observed due to herniation(arrow) . B: After surgery, the cauda equina is clearly visualized (arrowhead) . The FA level increased as the symptoms improved. Regarding the FA and ADC values and the clinical symptoms JOA score.(C) The preoperative JOA scores and FA values were positively correlated(r＝0.797, p＜0.001) .(D) The ADC values were negatively correlated(r＝－0.646, p＜0.05) . From Eguchi et al., modified with permission［17］