A comparison of the performance of anatomical MRI and DTI in diagnosing carpal tunnel syndrome

•The good parameters of both scans in CTS diagnosis were CSA(P1), FA(P1) and FA(P0).•Median nerve signal intensity and flexor retinacular bowing were not significantly different between CTS and controls.•The prestenotic swelling of median nerve of CTS was demonstrated as relatively large CSA and low FA value at P1 level.•Combination of both scans in evaluation of carpal tunnel increased diagnostic performance, and provided merits of both scans.

PurposeTo compare the performance of anatomical magnetic resonance imaging (MRI) with that of diffusion tensor imaging (DTI) in the diagnosis of carpal tunnel syndrome (CTS).Materials and methodsWe performed 3T anatomical MRI and DTI on 42 patients and 42 age-matched controls. The median nerve cross-sectional area (CSA), relative median nerve signal intensity, and palmar bowing of the flexor retinaculum, assessed with anatomical MRI, and fractional anisotropy (FA) and apparent diffusion coefficient of the median nerve, assessed with DTI, were measured at four locations: the hamate level, the pisiform level (P0), the level located 1 cm proximal to the P0 level (P1), and the distal radioulnar joint level (DR). Adding the ratios and differences of the median nerve parameters between the measurements at the DR and other locations to the diagnostic parameters, we evaluated the area under the receiver operating characteristic curves (AUCs) of all the diagnostic parameters of both scans.ResultsThe AUCs of FA(P1) (0.814) and FA(P0) (0.824) in DTI were larger than the largest AUC for anatomical MRI, CSA(P1) (0.759). However, the receiver operating characteristics of the three parameters were not significantly different (P > 0.1). The sensitivity and specificity of CSA(P1) (76.2% and 73.8%) and FA(P1) (73.8% and 76.2%) increased after inclusive and exclusive combination to 90.5% each.ConclusionThe individual performances of both scans were not significantly different in diagnosing CTS. Measuring both CSA and FA at P1 may be useful and efficient to utilize the merits of both scans and to increase the CTS diagnostic performance.