Diffusion Tensor MR Imaging In Assessment Of Carpal Tunnel Syndrome At3.OT:Comparison With Electrophysiological Studies

Objective：To assess the value of conventional magnetic resonance imaging(MRI) and diffusion tensor imaging(DTI) in the qualitative and quantitativediagnosis of carpal tunnel syndrome (CTS). To determine the role of DTI in theclassification of CTS by comparison with electrophysiological examination.Materials and Methods：The16healthy volunteers and21patients wereenrolled, and their age and gender were matched each other. All volunteers andpatients were performed conventional MRI and DTI examination, andelectrophysiological examination. The following4slices of MR images wereselected to conduct research:distal radius slice, proximal carpal tunnel slice(pisiform bone slice), middle carpal tunnel slice, and distal carpal tunnel slice(hamate bone slice). We measured the median nerve crosss-sectional area (CSA) ofdistal radius slice and proxiamal carpal tunnel slice, and then calculated the mediannerve swelling ratio (MNSR) on the basis of the value of them. The ratio of thenerve′s major to its minor axis distal carpal tunnel level was calculated as Flatteningof the median nerve (median nerve flattening ratio, MNFR). At the hamate bonelevel, measured the horizontal distance between the both attachment points of theflexor retinaculum and the displacement distance from palmaris, and recognized asbowing ratio (BF) of the palmar. Based on the DTI sequence, we measured the valueof FA and ADC. All the parameters between patients and volunteers were performedindependent-samples t test. Correlation analysis was done between all the MRIparameters and the electrophysiological results. Based on electrophysiologicalresults, patients were classified into mild, moderate and severe groups. Because thenumber of patients in severe group is too small (2patients), we put moderate andsevere groups together as a moderate-severe group(MSG) The FA was carried on thestatistical analysis using independent-samples t test. Results:Coventional MRI findings of CTS included: the MNSR, MNFR and bowingratio were significantly higher in patients than in volunteers. Increased signalintensity of the mdeian nerve on fat-suppression T2WI sequence can be seen inthirty-one wrists of all patients.DTI findings of CTS: Mean FA values were remarkable lower in patients thanin volunteers(p＜0.01). Mean ADC values were mildly higher in patients than involunteers, but there were no statistical differences between them (p＞0.05). Therewere visual modification of the tractography images between patients and volunteers.The MRI parameters of patients compared with electromyography ones: Asignificant negative linear correlation was found between mean FA values andelectrophysiological degrees(r,p). However, there was no linear correlation betweenall the other MRI parameters (MNSR, MNFR, BR, mean ADC values) andelectrophysiological degrees(r,p). The difference of mean FA values between MGand MSG is significantly(p＜0.01).Conclusion：Conventional MRI and DTI not only reflect the pathological nerve,but also assess CTS by quantitative diagnostic parameters. In addition, we found thatthey can contribute to the classification of CTS by comparison with electrophys-iological results.