Characterization of adrenocortical tumors by F-FDG PET/CT: Does steroid hormone hypersecretion status modify the uptake pattern?

Background: adrenal tumor-to-liver uptake value (Tmx:Lmx) on F-FDG PET/CT is an accurate and reproducible PET parameter in the distinction between benign and malignant adrenal masses. The potential impact of steroid hormone secretion on F-FDG uptake is still debatable. The aim of this study was to evaluate this relationship.

Methods: 2010-2015: 73 patients who underwent adrenalectomy for adrenocortical tumors [49 secreting/(SA) and 24 non-secreting/(NSA)] were retrospectively included in the study. Fourteen were malignant. All patients underwent hormonal evaluation, functional and anatomical imaging, Weiss scoring and Ki 67 evaluation.

Results: malignant tumors exhibit higher SUVmax than benign tumors (median 7.75 vs 3.06 respectively, p < 0.001) and Tmx:Lmx was 2.7 vs 1.17 for benign tumors, p < 0.001. Tmx:Lmx was positively correlated to Weiss score (p < 0.001). No significant difference was observed for Tmx:Lmx between SA and NSA overall (p = 0.851), regardless of the subgroup of tumors analyzed. Tmx:Lmx was not correlated to tumor size (p < 0.508) or 24 h free urinary cortisol level (p < 0.522).

Conclusions: no correlation was observed between Tmx:Lmx and hormonal status, however the correlation between ratio, malignancy and Weiss score confirm the utility of F-FDG PET/CT for the differentiation of benign from malignant adrenal lesions, irrespective of the hormone secretory status of the tumor. F-FDG PET/CT is a useful biomarker in the diagnosis of adrenal tumors, regardless of the secretion status.