Utility of Sonoelastography and Magnetic Resonance Imaging in Characterization of Thyroid Nodules

To evaluate thyroid nodules with sonoelastography and magnetic resonance imaging (MRI).

The study included 28 patients with 40 thyroid nodules. Clearance was obtained from the institute's ethical clearance committee. Patients with pure cystic nodules or nodules with eggshell calcification, diffuse thyroid pathology (such as Graves' disease, Hashimoto's thyroiditis, De Quervain thyroiditis, and Riedel's thyroiditis), inaccessible nodules via fine needle aspiration cytology (FNAC), or patients with a history of thyroid gland surgery were excluded from the study. Strain elastography was performed on a Phillips iU22 machine, producing qualitative color-coded strain maps (graded using the Rago 5-point system) and semiquantitative strain ratios. MRI was performed on a Phillips ACHIEVA 1.5T magnet with a head and neck coil.

Rago scores statistically correlated (χ² = 18.052, p < 0.001) with malignant nodules, and using the receiver operating characteristic (ROC) curve, the area under the ROC curve (AUROC) for the mean strain ratio predicting malignant outcomes was 0.88 [95% confidence interval (CI): 0.767-0.992], which was also statistically significant (p < 0.001). A cutoff of mean strain ratio ≥2.48 predicted malignant outcomes with 100% specificity. T2 signal intensity ratio (SIR) and apparent diffusion coefficient (ADC) values were not statistically significant in predicting malignant outcomes. Kinetic curves were statistically significant for Rago scores (χ² = 11.356, p = 0.045); however, no significant difference was found in predicting malignant outcomes.

We concluded that sonoelastography, along with grayscale ultrasound, is a useful noninvasive technique for predicting histological outcomes. However, MRI should largely be reserved as a problem-solving tool rather than a standalone imaging modality. The kinetic curves show some degree of overlap between histologically distinct diseases, and thus large-scale multicenter trials are needed for further standardization.