Relationship between cervical diffusion tensor imaging and somatosensory evoked potential in patients with cervical intraspinal tumors

Abstract

Objective To explore the correlation between cervical diffusion tensor imaging (DTI) and median nerve short latency somatosensory evoked potential (MN-SLSEP) parameters in patients with cervical intraspinal tumors. Methods Twenty-two patients suffering from cervical intraspinal tumors treated with surgical resection were enrolled into study group from February 2015 to May 2016; meanwhile, 22 age-matched volunteers were selected as control group. Cervical DTI and MN-SLSEP detection were performed 3 d before operation and one month after operation, respectively. The whole cervical spinal cord was divided into 3 areas, the tumor head area, the tumor area, and the tumor tail area; and the fractional anisotropy (FA) values of the 3 areas were calculated. The white matter fiber bundle was reconstructed by diffusion tensor tracking (DTT) to observe its integrity. Study group was further divided into delayed latency group (lat+ group) and normal latency group (lat group) according to the delayed latency of N9-N20 interpeak levels, and the FA values of the 3 groups at different areas were compared. Results Total removal of the tumors was achieved in 19 patients(86.4%) and subtotal in 3 patients (13.6%, two with nerve fibrolipomas and one with intramedullary neurilemmomas) of the study group. One month after the operation, the spinal function was improved in 17 patients (77.3%), and not improved in 5 patients (22.7%). The preoperative N9-N20 interpeak latency in the study group was significantly longer than that in the control group (P<0.05). In term of preoperative fiber tract morphology of study group, the proportion of delayed N9-N20 interpeak latency in patients with interrupt type (75%) was significantly longer than that in the patients with intact type (21.4%, P<0.05). FA values of lat+ and lat group in the tumor head area, tumor area, and tumor tail area were significantly lower than those in the control group (P<0.05); and FA values of lat+ group in these three regions were significantly lower than lat group (P<0.05). Conclusions DTI metrics correlate with MN-SLSEP measures. Through variations of quantitative parameter values and fiber tract morphology, cervical DTI can sensitively and intuitively reflect the electrophysiological changes, which could be served as a important diagnostic tool for cervical intraspinal tumors. Key words: Diffusion tensor imaging; Diffusion tensor tracking; Fractional anisotropy; N9-N20 interpeak latency; Somatosensory evoked potential; Cervical intraspinal tumor