Maximal stiffness evaluation by real-time ultrasound elastography, an improved tool for the differential diagnosis of...

The aim of the study was to evaluate the diagnostic performance of a new ultrasound elastography (USE) parameter based on the measurement of the percentage of maximal stiffness within a nodule as compared with the already established elastographic strain index (SI) and to investigate their diagnostic performance according to nodule size.

The study included 218 nodules. Each nodule underwent conventional ultrasound (US), USE evaluation, and fine-needle aspiration cytology (FNAC). Thyroid nodules were further stratified into 4 subgroups (G) according to their size (G1, <1 cm; G2, 1-2 cm; G3, >3 cm). USE evaluation comprised the measurement of the percentage of the areas included in the region of interest corresponding to the maximal stiffness (% Index) and of the SI.

The % Index and of the SI were significantly higher in malignant than in benign thyroid nodules, and both measurements displayed a good diagnostic performance (SI sensitivity and specificity, 0.66 and 0.90, respectively; % Index sensitivity and specificity, 0.76 and 0.89, respectively). Compared with SI, the % Index was more informative, both in the whole group of thyroid nodules (odds ratio [OR], 18.68; 95% confidence interval [CI], 6.06 to 63.49; P<.0001 versus OR, 26.15; 95% CI, 8.01 to 102.87; P<.0001, respectively) and in the G1 and G2 subgroups.

The % Index is a stronger predictor of nodule malignancy than both the SI and the conventional US signs. This is particularly true in nodules smaller than 1 cm, which are more difficult to explore both by conventional US and FNAC.