Endocrine Abstracts

Objectives: The aim of the study was to determine different types of thyroid nodules according to their elasticity and to evaluate the diagnostic accuracy of strain elastography in detection of thyroid cancer. 114 thyroid nodules in 84 patients were examined prospectively with conventional B-mode US, color Doppler, strain elastography (SE) and fine needle aspiration biopsy (FNAB). 72 nodules in 50 patients were submitted to surgery and histologically assessed. For final diagnosis we accepted histology in operated cases and cytology for the rest.

Results: After performing SE, the image was matched to a modified 5 scale scoring system, based on the one of Ueno and Ito. 32.9% of benign and 0% of malignant nodules presented with highly elastic structure - score 1 (P<0.0001). Elasticity in a large area of the nodule (score 2) was present in 34.2% of benign and 5.3% of malignant nodules (P=0.0005). Indeterminate elasticity (score 3) had 26.3% of benign and 18.4% of malignant lesions (P=0.4839). No elasticity (score 4) was determined in 6.6% of benign and in 55.3% of malignant nodules (P<0.0001). Stiffness in nodule and surrounding tissue (score 5) was registered in 21.1% of malignant and none of benign lesions (P<0.0001). Sensitivity, specificity, PPV, NPV and accuracy were 76.3%; 93.4%; 85.3%; 88.8%; 87.7% for SE; 89.5%; 86.2; 79.1%; 94.4%; 89% for combining B-mode and SE; and 92.1%; 93.4%, 87.5%; 95.9%; 93% for combining B-mode, SE and FNAB, respectively.

Conclusions: The high specificity and NPP of SE alone or as an adjunct to conventional US suggests that high elasticity is a promising criterion for excluding malignancy and that this non-invasive technique may limit the indications for FNAB. Combination of three methods (B-mode, SE and FNAB) has the highest diagnostic accuracy in differentiating malignant from benign nodules and permits the clinician exact selection of patients who would benefit from surgery.