Diffusion-weighted magnetic resonance neurography for the diagnosis of carpal tunnel syndrome: a pilot study

To investigate the applicability of diffusion-weighted magnetic resonance neurography (DW-MRN) in the diagnosis of carpal tunnel syndrome (CTS).

In total, 47 patients with CTS (69 wrists) and 19 normal participants (38 wrists) was included in this study. Cross-sectional area (CSA) and apparent diffusion coefficient (ADC) values of the median nerves in the carpal tunnel were determined using DW-MRN. Receiver operating characteristic (ROC) analysis was performed.

No significant differences in age or body mass index (BMI) were observed between the control and CTS groups. DW-MRN imaging showed obvious hyperintensity in the lesions in CTS wrists, while other nerve regions were related to slight hyperintensity. Interobserver variability analysis indicated excellent agreement regarding both the CSA and ADC measurements for the control and CTS groups. Both the mean CSA and ADC values of the median nerves in carpal tunnel in the CTS group were significantly higher than the control group. According to the ROC analysis, the CSA cut-off value was 11.7 mm², and sensitivity and specificity were 66.7% and 89.5%, respectively. Conversely, the median nerve ADC cut-off value was 1.047×10^-3 mm²/s. The sensitivity and specificity were 91.3% and 76.3.9%, respectively.

DW-MRN represents a highly reproducible diagnostic technique for CTS. The ADC value of median nerves in the carpal tunnel is significantly higher in CTS patients, which provides a potential powerful tool for the disease diagnosis.