Diffusion tensor imaging in carpal tunnel syndrome

PURPOSE We aimed to investigate the efficacy of diffusion tensor imaging in the diagnosis of carpal tunnel syndrome and to obtain a quantitative parameter that may contribute to the diagnosis. MATERIALS AND METHODS The median nerves in 57 wrists of 38 patients diagnosed as carpal tunnel syndrome and 30 wrists of 24 normal subjects were prospectively evaluated with a 3T Philips scanner, using standard 8-channel SENSE head coil. Diffusion tensor imaging was performed using spin echo-echo planar imaging. For anatomical reference, a T1-weighted sequence was acquired. Fractional anisotropy and apparent diffusion coefficient measurements were done focally at the carpal tunnel level and from whole median nerve. RESULTS In carpal tunnel syndrome patients, both focal carpal tunnel and whole nerve measurements demonstrated statistically significantly lower fractional anisotropy values than normal subjects (P < 0.001). No statistically significant difference was observed in apparent diffusion coefficient measurements. The cut-off value obtained by receiver operator characteristics analysis was 0.554 for focal carpal tunnel fractional anisotropy (sensitivity, 80%; specificity, 80%) and 0.660 for whole nerve fractional anisotropy (sensitivity, 82%; specificity, 80%) measurement. CONCLUSION Diffusion tensor imaging may contribute to the diagnosis of carpal tunnel syndrome on the basis of fractional anisotropy measurements.