Characterization of adrenocortical tumors by 18F-FDG PET/CT: Does steroid hormone hypersecretion status modify the uptake pattern?

BACKGROUND

adrenal tumor-to-liver uptake value (Tmx:Lmx) on 18F-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 18F-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 18F-FDG PET/CT for the differentiation of benign from malignant adrenal lesions, irrespective of the hormone secretory status of the tumor. 18F-FDG PET/CT is a useful biomarker in the diagnosis of adrenal tumors, regardless of the secretion status.