Value of strain-ratio on thyroid real-time sonoelastography

The aim of this study was to determine the accuracy of elastosonography in the differential diagnosis of thyroid nodules using a qualitative [evaluation of the stiffness score (SS)] and quantitative assessment [evaluation of the strain ratio (SR)].

In our single-centre retrospective study, 368 patients were enroled between December 2010 and March 2012 (134 men, 234 women, mean age 56.1 ± 14.2) with a diagnosis of thyroid nodules, who underwent conventional ultrasonographic and elastosonographic evaluation. The SS and SR were assessed and the results were expressed in terms of sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). The nodules were subjected to needle aspiration.

Forty-four nodules were malignant (TIR ≥ 3) and 324 benign on cytological analysis. Considering a cut-off of SS > 2, we had 91% sensitivity, 68% specificity, 27% PPV and 98% NPV. Considering a cut-off of SR ≥ 3.28, we had 81.8% sensitivity, 82.7% specificity, 39.1% PPV and 97.1% NPV.

The SR calculation did not provide additional data to the SS, which remains the elastosonography benchmark. It will be necessary to validate these preliminary data by larger prospective randomised trials.