Characterization of adrenal masses with non-enhanced CT and 18F FDG-PET in patients with primary malignancies

ABSTRACT

Background: Characterizing adrenal lesions in patients with a known primary malignancy has a vital role in treatment and prognostication. A study by Gufler et al proposed a scoring system based on density, contour, homogeneity and size and found a high accuracy in differentiating adrenal adenomas from metastasis in patients with a known malignancy. This study evaluates the sensitivity and specificity of this NECT scoring system and comparing it with that of 18F FDG PET.Methods: The study was conducted on patients with diagnosed malignancies with adrenal mass, referred for 18F-FDG PET-CT scanning as a part of work up or follows up between October 2014 and March 2016. Whole-body CT and PET images were obtained using standard protocol. NECT scoring and quantitative analysis of FDG uptake in the adrenal lesions (SUVavg analysis) is done separately.Results: Of the 50 patients studied, 33 patients had benign adrenal lesions and the rest had metastatic lesions. Most common site of primary was lung. NECT score yielded a sensitivity of 88.2%, specificity of 100% and positive predictive value of 100%. SUVavg analysis yielded a 100% sensitivity, specificity and positive predictive value. Comparison of the predictive power of the two tests showed a z score of 2.5 and p value of 0.0124.Conclusions: 18-FDG PET can be considered as a gold standard for differentiating between metastasis and benign lesions of adrenal glands in patients with known primary. NECT has a comparable specificity as that of FDG PET, however with lower sensitivity.