The efficiency of elastography in the diagnostics of follicular lesions and nodules with an unequivocal FNA result.

Abstract

The aim was to assess the usefulness of strain elastography (SEG) in the diagnostics of two groups of thyroid nodules (TNs): follicular lesions (FL) with low malignancy risk (< 20.0%) and low percentage of papillary carcinomas (PTCs) among cancers as well as TNs with unequivocal cytology (UC) and high percentage of PTCs among cancers. 168 TNs were analysed and eventually surgically treated: 100 UC (50 benign and 50 malignant - 90.0% PTCs) and 68 FL (60 benign, 8 malignant - 50.0% PTCs). Elasticity score (ES) and strain ratio (SR) were evaluated, and their effectiveness was compared with the evaluation of the number of ultrasound malignancy risk features (NoUMRFs). In the UC group the evaluation of mean values of SR and ES in both sections (meanSR, meanES) was more efficient than NoUMRFs analysis (AUC: 0.903 and 0.869 vs. 0.754, p < 0.05). The following thresholds: meanSR ≥ 2.01, meanES ≥ 2.5, NoUMRFs ≥ 2, were related to the increased malignancy risk in nodules (OR: 45.0; 23.2; 5.4, respectively), but only meanSR ≥ 2.01 was an independent risk factor (OR: 20.3; SEN: 86.0%, SPC: 88.0%). In the FL group, only the evaluation of tSR (SR assessed in transverse section) had the value of AUC > 0.7, and only the set of features: tSR ≥ 1.7 and NoUMRFs ≥ 1 increased the malignancy risk in nodules (OR: 12.0; SEN: 75.0%, SPC: 75.0%). SEG is more reliable than conventional US in the diagnostics of TNs. The efficacy of SEG decreases with lowering percentage of PTCs among cancers. But in FL nodules SEG may support the selection of nodules for surgical treatment.