Application of ultrasound elastography for determining carpal tunnel syndrome severity

To evaluate grey-scale and elastography ultrasound imaging findings in patients with CTS compared to nerve conductive studies. Sixty median nerves of 31 cases with confirmed CTS and 44 median nerves in 22 controls (healthy volunteers) who had no clinical evidence of CTS were evaluated. An expert radiologist performed all US evaluations. The RGB image is a three-dimensional matrix. A colour image RGB is an M x N x 3 array of colour pixels. The total pixels, total blue and red pixels, and blue and red indexes were compared between cases and controls. Of the 60 nerves in the cases, 17 (16.3 %) were mildly affected, 30 (28.8 %) were moderately affected, and 13 (12.5 %) were severely affected. Mean CSA, total blue pixels and blue indexes were significantly different between controls and cases with different levels of disease severity. The best cut-off point in the blue index to differentiate patients from controls was 0.1486, with a sensitivity and specificity of 80 and 70 % (AUC = 0.79, P < 0.001), respectively. The best cut-off point for the red index to differentiate patients from controls was 0.1896, with a sensitivity and specificity of 70 and 55 % (AUC = 0.64, P = 0.01), respectively. Sono-elastography could be a useful diagnostic method for evaluating CTS severity in affected cases.