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.

<bold>Objective: </bold>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.<bold>Methods: </bold>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.<bold>Results: </bold>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).<bold>Conclusions: </bold>Our results indicated that calcification in mLNs related to the ability of (131)I accumulation and less dedifferentiation. [ABSTRACT FROM AUTHOR]