Ultrasonographic Features of Medullary Thyroid Carcinoma: Do they Correlate with Pre and PostOperative Calcitonin Levels?

Purpose: To correlate ultrasonographic (US) features of medullary thyroid carcinoma (MTC) with pre operative and postoperative calcitonin levels.

Materials And Methods: A total of 130 thyroid nodules diagnosed as MTC were evaluated. Two radiologists retrospectively evaluated preoperative US features according to size, shape, margin, echogenicity, type of calcification, and lymph node status. Postoperative clinical and imaging followup (mean duration 31.9 ± 22.5 months) was performed for detection of tumor recurrence. US features, presence of LN metastasis, and tumor recurrence were compared between MTC nodules with and without elevated preoperative calcitonin (>100 pg/mL). Those with normalized and nonnormalized postoperative calcitonin levels groups were also compared.

Results: Common US features of MTCs were solid internal content (90.8%), irregular shape (44.6%), circumscribed margin (46.2%), and hypoechogenicity (56.2%). Comparing MTC nodules with and without elevated preoperative calcitonin levels, the size and shape of MTC nodule and lymph node metastasis showed statistical significance (p<0.05). Postoperative calcitonin normalization correlated with US features of tumor size (p=0.002), margin (p=0.034), shape (p≤0.001), and presence of calcification (p=0.046). Tumor recurrence and LN metastasis were more prevalent in patients without normalization of postoperative calcitonin than in those with normalization (p=0.001).

Conclusions: Serum calcitonin measurement is helpful for early diagnosis and predicting prognosis. Postoperative calcitonin measurement is also important for postoperative US follow up, especially in cases with larger nodule size, presence of calcification, irregular shape, and irregular margin.