Can calcification predict 131I accumulation on metastatic lymph nodes in papillary thyroid carcinoma patients receiving 131I therapy? Comparison of CT, 131I WBS and 18F-FDG PET/CT.

ABSTRACT

OBJECTIVE: The aim of this study was to clarify the predictive significance of nodal calcification in terms of the therapeutic option of (131)I therapy in papillary thyroid carcinoma (PTC) patients. METHODS: We reviewed 19 computed tomography (CT) examinations of PTC patients on receiving (131)I therapy for the presence of nodal calcification, and compared the (131)I whole-body scintigraphy and (18)F-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)/CT findings. The metastatic lymph nodes (mLNs) were divided into three groups A, those with calcification; B, those without calcification but belonging to patients who had calcified mLNs; C, those without calcification and belonging to patients who had no calcified mLNs. The incidences of (131)I accumulation and maximum standardised uptake values (SUV max) in the three groups were compared. RESULTS: A total of 70 mLNs were evaluated. Twelve mLNs belonged to group A, 13 to group B and 45 to group C. The incidences of (131)I accumulation were significantly higher in groups A (100%) and B (100%) than in group C (11.1%) (p < 0.0001 for both). The SUVmax was significantly lower in groups A (4.1 +/- 1.9) and B (3.9 +/- 1.4) than in group C (7.1 +/- 4.4) (p = 0.01, p = 0.002, respectively). CONCLUSIONS: Our results indicated that calcification in mLNs related to the ability of (131)I accumulation and less dedifferentiation.