Purpose: Ultrasound of the neck detects a large number of non-palpable thyroid nodules in the population, but it offers poor diagnostic accuracy (the presence of microcalcifications is the only statistically significant criterion indicative of malignancy). The aim of this study is to evaluate elastography, a technique which allows differentiation between pathological and normal tissue by determining its hardness and which could also prove useful in the characterisation of thyroid nodules.
Materials and methods: In this prospective study, 51 thyroid nodules in 40 consecutive patients were examined (25 women, 15 men, mean age +/- SD, 54 +/- 13.4). Elastosonography was performed by real-time, free-hand technique, using Logos HiVision equipment with a 10 MHz transducer and lesions were classified and scored in 4 classes of hardness. All patients were also examined by grey scale high frequency ultrasound and colour Doppler. Final diagnoses were obtained from cytological and/or histological evaluation.
Results: Final diagnoses revealed 11 malignant and 40 benign nodules. Only in two cases ultrasound demonstrated signs useful for a differential diagnosis (intrinsic microcalcifications). Correct differentiation of malignant from benign nodules was obtained by elastosonography in 43 / 51 cases with 5 false positives (FP) and 3 false negatives (FN). Specificity, sensitivity and accuracy were 87.5 %, 81.8 % and 86.2 %, respectively. Predictive negative value (PNV) and predictive positive value (PPV) were 94.5 % and 64 % area under the curve (AUC) 0.86.
Conclusion: Elastosonography provides an interesting contribution to the differentiation of malignant and benign thyroid nodules. Particularly worthy of mention is that an entirely elastic nodule pattern was observed only in relation to benign nodules, a result which would suggest that immediate recourse to FNAB might be avoided.