The Diagnostic Value of [18F] FDG PET/CT Scan in Characterizing Adrenal Tumors.

Abstract

Imaging plays an important role in the characterization of adrenal tumors, but findings might be inconclusive. The clinical question is whether [18F] FDG PET/CT is of diagnostic value in this setting. This meta-analysis was aimed at the diagnostic value of [18F] FDG PET/CT in differentiating benign from malignant adrenal tumors discovered either as adrenal incidentaloma or during staging or follow-up of oncologic patients. PubMed, EMBASE, Web of Science and Cochrane Library were searched to select articles between 2000-2021. We included studies describing the diagnostic value of [18F] FDG PET/CT in adult patients with an adrenal tumor. Exclusion criteria were ≤10 subjects, insufficient data on histopathology, clinical follow-up, or PET results. After screening of title and abstract by two independent reviewers, 79 studies were retrieved of which 17 studies met the selection criteria. Data extraction using a protocol and quality assessment according to QUADAS-2 was performed independently by at least two authors. A bivariate random effects model was applied using R (version 3.6.2.). Pooled sensitivity and specificity of [18F] FDG PET/CT for identifying malignant adrenal tumors was 87.3% (95%CI; 82.5%-90.9%) and 84.7% (95%CI; 79.3%-88.9%), respectively. The pooled diagnostic odds ratio (DOR) was 9.20 (95%CI; 5.27-16.08, P < 0.01). Major sources of heterogeneity (I2, 57.1% (95%CI; 27.5%-74.6%)) were in population characteristics, reference standard and interpretation criteria of imaging results. [18F] FDG PET/CT had good diagnostic accuracy for characterization of adrenal tumors. The literature, however, is limited, in particular regarding adrenal incidentalomas. Large prospective studies in well-defined patient populations with application of validated cut-off values are needed.