Diagnostic Value of Virtual Touch Tissue Imaging Quantification for Evaluating Median Nerve Stiffness in Carpal Tunnel Syndrome

Objectives: To measure the shear wave velocity (SWV) of the median nerve by Virtual Touch tissue imaging quantification (VTIQ; Siemens AG, Erlangen, Germany) through the beginning of the carpal tunnel and to determine whether VTIQ could be used to diagnose carpal tunnel syndrome. Methods: This study recruited 49 consecutive patients (72 wrists) with a definitive diagnosis of carpal tunnel syndrome and 23 healthy volunteers (46 wrists). We measured the median nerve diameter and cross-sectional area by 2-dimensional sonography and the SWV by VTIQ. The interobserver variability was analyzed, and diagnostic values were evaluated by drawing a receiver operating characteristic curve. Results: The median nerve SWV was significantly higher in the carpal tunnel syndrome group (3.857 m/s) than the control group (2.542 m/s; P <.05). A 3.0-m/s SWV cutoff value revealed sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 83.3%, 91.3%, 93.8%, 77.8%, and 86.4%, respectively. The interobserver agreement was excellent for the SWV measurements. Conclusions: The median nerve SWV at the carpal tunnel inlet is significantly higher in patients with carpal tunnel syndrome, for whom VTIQ appears to be a highly reproducible diagnostic technique.