Endocrine Abstracts

Background: Elastography is a procedure that widen diagnostic ultrasonography (US) but its significance in thyroid diagnostics has not been settled.

Aim: Comparison of usefulness of elastography and conventional malignancy risk features (MRF) in the diagnostics of thyroid nodules, analysis of elastographic characteristics of follicular lesions of undetermined significance (FLUS).

Methods: Analysis included 38 benign lesions (BL), 15 malignant neoplasms (MN) and 67 FLUS. MRF (according to current recommendations), elastography score (ES) based on 4-grade scale of tissue stiffness and strain ratio (SR) of examined lesion and surrounding tissue were evaluated.

Results: MN more often than BL showed MRF>1 (66.7 vs 34.2%; P<0.05). Suspicious elastogram (ES>2) was observed in MN more often than in BL (65.5 vs 32.0; P<0.005). Relative risk (RR) of malignancy rose when SR>2 (RR=9; P<0.001); SR>2 was observed in MN more frequently than in BL (66.7 vs 29.7%; P<0.01). Moderate positive correlation between SR and ES was found (r=0.58; P<0.05), as well as low positive correlation between ES>2 and MRF>1 (tau b=0.28; P<0.05). MRF>1, ES>2, SR>2 sensitivity were similar (66.7; 65.5; 66.7% respectively). Combining both elastography parameters (ES>2 or SR>2) increased sensitivity of the elastography to 91.7%, specificity 51.4%. Adding MRF>1 feature did not significantly improve sensitivity (92.3%) yet it decreased specificity (34.3%). Using single elastography parameter associated with MRF>1 feature was also less effective (SR or MRF>1: sensitivity-91.7%, specificity-45.5%; ES or MRF>1: sensitivity-80.0%, specificity-47.4%). FLUS showed similar elastography features to BL (ES>2–27.1%, SR>2–24.8%) while being similar to MN in >1MRF evaluation (62.7%) and different from BL (P<0.01).

Conclusions: Sensitivity of single elastography or MRF is similar. Still, combining both ES and SR is more effective than MRF evaluation. Considering 5% malignancy risk in FLUS in our population, FLUS elastography characteristic is more reliable than MRF analysis.