Which Ultrasound Parameter Is More Accurate in the Diagnosis of Carpal Tunnel Syndrome: Cross-Sectional Area, Resistive Index, or Strain Ratio?

Abstract

The aim of this study was to compare the accuracy of cross-sectional area (CSA), resistive index (RI), and strain ratio (SR) in carpal tunnel syndrome (CTS). This prospective and case-control study included patients with a diagnosis of CTS and a healthy control group. The participants were examined with an ultrasound Doppler system equipped with a high-resolution (5-18 MHz) linear probe (Philips L18-5). CSA, RI, and SR values were compared. CSA, RI, and SR were found to be effective tools to detect the presence of CTS (regardless of severity). The cut-off value of 11.25 mm for CSA had a sensitivity and specificity of 97.2% and 88.0%, respectively. The cut-off value of 0.740 for RI had a sensitivity and specificity of 94.4% and 94.0%, respectively. The cut-off value of 1.95 for SR had a sensitivity and specificity of 97.2% and 84.0%, respectively. In respect of the severity of CTS, ultrasound was found to be an effective method to classify severe CTS cases only. The CSA, SR, and RI seem to have excellent accuracy in the diagnosis of CTS. When the grading of severity is considered, ultrasound seems to be sensitive and specific in differentiating severe CTS cases from mild or moderate CTS cases.