Body surface area-adjusted median nerve cross-sectional area and multimodal ultrasound improve diagnosis of carpal tunnel syndrome.

BACKGROUND

To evaluate the diagnostic performance of high-frequency ultrasound combined with Superb Microvascular Imaging (SMI) and Shear Wave Elastography (SWE) for carpal tunnel syndrome (CTS), and to develop an individualized diagnostic approach using a body surface area (BSA)-adjusted median nerve CSA at the pisiform level.

MATERIALS AND

METHODS

This retrospective study included 47 wrists with carpal tunnel syndrome (CTS) and 94 control wrists. Median nerve cross-sectional area (CSA) was measured at four anatomical sites. Superb Microvascular Imaging (SMI) and Shear Wave Elastography (SWE) were used to assess intraneural vascularity and stiffness, respectively. A linear regression model was developed to estimate the expected CSA at the pisiform level based on body surface area (BSA), and a BSA-based Z-score was calculated accordingly. Receiver operating characteristic (ROC) analyses were performed to compare the diagnostic performance of (i) a fixed CSA cutoff at the pisiform level, (ii) the BSA-based Z-score, and (iii) a combined SMI + SWE logistic regression model.

RESULTS

Ultrasound parameters differed significantly between the CTS and control groups (P < 0.05). The BSA-based Z-score derived from the CSA at the pisiform level yielded an AUC of 0.924 (95% CI 0.879-0.969) and improved specificity (83%; 95% CI 0.738-0.899) compared with the fixed CSA cutoff (75%; 95% CI 0.644-0.829). In multivariable analysis, SMI- and SWE-derived parameters remained independent predictors of CTS (P < 0.001). The combined SMI + SWE logistic regression model demonstrated the best diagnostic performance (AUC 0.944; 95% CI 0.906-0.982), with 83% sensitivity (95% CI 0.692-0.924) and 90% specificity (95% CI 0.826-0.955).

CONCLUSION

High-frequency ultrasound combined with Superb Microvascular Imaging (SMI) and Shear Wave Elastography (SWE) enables accurate, noninvasive evaluation of CTS. A BSA-based CSA Z-score improves specificity in CSA-based diagnosis, and integrating SMI and SWE further enhances overall diagnostic performance.