Color and power Doppler US for diagnosing carpal tunnel syndrome and determining its severity: a quantitative image processing method

Purpose: To determine whether intraneural vascularity seen at color Doppler ultrasonography (US) can be used to diagnose carpal tunnel syndrome (CTS) and to evaluate an image processing method for quantifying the severity of CTS on the basis of this vascularity.

Materials and methods: This study was approved by the university ethics review committee. One hundred one patients with clinical evidence of CTS and 55 healthy control subjects were enrolled. Electrodiagnostic testing (EDT) was performed in all participants, and the presence of intraneural vascularity was evaluated with color Doppler US. An image processing program was designed by using software to determine the sum of pixels in the intraneural vascular area on power Doppler US scans of the median nerve. The relationship between the number of pixels and the severity of the abnormality at EDT was determined.

Results: The sensitivity (83%) and specificity (89%) of intraneural vascularity in the diagnosis of CTS were similar to those of EDT (81% and 84%, respectively). Intraneural vascularity was seen in 91.4% of patients with mild CTS and 100% of patients with moderate or severe CTS. In participants with positive intraneural vascularity, the sum of pixels in the intraneural vascular area was significantly higher in patients than in control subjects and paralleled the severity of the abnormality at EDT (P < .01).

Conclusion: Color Doppler US can be used to accurately diagnose CTS. By processing the recorded power Doppler images and determining the number of pixels in the intraneural vascular area, the severity of CTS can be assessed