Sonoelastography aids carpal tunnel diagnosis

Sonoelastography offers significant improvement in the diagnostic accuracy of the ultrasonographic assessment of carpal tunnel syndrome (CTS), according to a study published in the February issue of Radiology.

CTS currently has no standard of reference for diagnosis. However, the modality sonoelastography has shown promising results for the diagnosis of masses of the liver, breast, pancreas, prostate, and thyroid.

Lead author Hideaki Miyamoto, MD, of the Medical University Innsbruck in Austria, and colleagues compared the elasticity of the median nerve (MN) between 22 healthy volunteers and 31 patients with CTS, thereby evaluating the cross-sectional area and diagnostic usefulness of the elasticity of the MN measured with sonoelastography.

The study’s results revealed that the acoustic coupler (AC)/MN strain ratio and the cross-sectional area in patients with CTS were significantly higher than those in the healthy volunteers. CTS was predicted with AC/MN strain ratio and cross-sectional area cutoff values of 4.3 and 11 mm2, respectively. Areas under the receiver operating characteristic curves (AUC) were 0.78 and 0.85. The researchers used a logistic model that combined AC/MN strain ratio and the cross-sectional area, which improved diagnostic accuracy for CTS with an AUC of 0.91.

“We conclude that the MN in patients with CTS is stiffer than that in healthy subjects and that sonoelastography provides significant improvement in the diagnostic accuracy of the US assessment of CTS. Further studies are necessary to see how sonoelastography complements [cross-sectional area] measurements for evaluation of CTS,” wrote the study’s authors.