A Comparison of Detection Rates Between Ultrasound and Post‐Therapeutic I‐131 <scp>SPECT</scp> / <scp>CT</scp> for Cervical Lymph Node Metastasis in Papillary Thyroid Carcinoma

Ultrasound demonstrated superior detection of metastatic lymph nodes, identifying a substantial subset (32.7%) of RAI-refractory disease missed by SPECT/CT. SPECT/CT remains valuable for confirming RAI avidity and detecting occult functional disease. These findings support a combined imaging strategy according to the metastatic characteristics. The presence of microcalcifications and hypoechogenicity was an important sonographic predictor of malignancy, with Level VI being the most common and predictable site of metastatic involvement.