Using Elastographic Stiffness to Improve Risk Stratification in Medullary Thyroid Carcinoma

Background/Objectives: Medullary thyroid carcinoma (MTC) poses diagnostic challenges due to its sonographic similarity to benign nodules and the modest sensitivity of conventional ultrasound (US) and TIRADS-based risk stratification. Elastography, using strain (SE) and shear-wave (SWE) techniques, has demonstrated high accuracy in papillary thyroid carcinoma (PTC) but remains underexplored in MTC. This study investigates whether elastographic stiffness measurements can enhance diagnostic precision for MTC when combined with conventional US. Methods: We retrospectively analyzed 20 nodules confirmed as MTC by pathology after surgical resection (January 2013-June 2024) and evaluated via conventional US, SE, and SWE at a specialized endocrinology center. Elasticity scores (ES) and Emean/Emax values were compared with US features, TIRADS categories, calcitonin levels, nodule size, and lymph node status. Results: Qualitative SE showed a mean ES of 3.2 (55% ES 4, 20% ES 3), while 87.5% of nodules exceeded an SWE Emean cutoff of 30.5 kPa, indicating increased stiffness in most MTC nodules and outperforming TIRADS, where only 60% were high-risk. Moderate correlations were found between calcitonin and nodule size (r = 0.52, p = 0.018) and between ES and size (r = 0.48, p = 0.034), but calcitonin did not correlate with ES (r = 0.07, p = 0.768). Nodules with suspicious lymph nodes showed higher Emean and ES trends, though not significant. Conclusions: Elastography identifies increased stiffness in MTC, challenging its "soft" classification, and improves risk stratification beyond TIRADS. We suggest integrating elastography as a complementary tool alongside TIRADS to guide fine-needle aspiration, without replacing calcitonin or cytology. Prospective multicenter studies are needed to validate thresholds and optimize multimodal risk assessment in MTC.