ARFI elastography for differentiating malignant and benign thyroid nodules

Abstract

Aim: To examine the diagnostic performance of virtual touch tissue quantification (VTQ) mode of Acoustic Radiation Force Impulse (ARFI) elastography imaging in differentiating benign and malignant thyroid nodules. Materials and Methods: Two hundred four solid and mostly solid nodules >5mm were prospectively evaluated with ultrasonography, VTQ mode of ARFI elastography, fine needle aspiration biopsy, and when indicated with tissue pathology. Three shear-wave velocities (SWV) measurements were done in 196 nodules. The SWV ratio for each nodule was calculated as the mean value of the SWV of the nodule divided by the mean value of the adjacent parenchyma. The diagnostic performance of SWV value and SWV-ratio were assessed by a receiver-operating characteristic (ROC) curve analysis. Results: The mean SWV value in the normal parenchyma, in benign and malign thyroid nodules, were 2.13±0.44 m/s, 2.06±0.80 m/s, and 2.06±0.88 m/s respectively. The SWV-ratios were 0.97±0.37 for benign thyroid nodules and 1.02±0.40 for malignant thyroid nodules. There was no significant difference between benign and malign nodules in terms of mean SWV values (t=0.008) (P=0.994) or SWV-ratios (t =0.596; P=0.527). No cut-off point was found to predict malignancy. In subgroup analysis, AUCs for the SWV and SWV-ratio were significantly different between nodules ?10 mm and those ?10 mm, but not with any other two groups (all P>0.05) (Table-2). The cutoff points for the differential diagnosis were 2.59 m/s for SWV and 1.0 for SWV- ratio respectively for nodules <10 mm. Conclusion: VTQ mode of ARFI imaging does not have a good diagnostic performance for detecting malignancy and cannot contribute to reducing unnecessary thyroid biopsies.