The Diagnostic Value of F-18-FDG PET/CT Scan in Characterizing Adrenal Tumors

Context Imaging plays an important role in the characterization of adrenal tumors, but findings might be inconclusive. The clinical question is whether F-18 fluodeoxyglucose (F-18-FDG) positron emission tomography/computed tomography (PET/CT) is of diagnostic value in this setting. Objective This meta-analysis was aimed at the diagnostic value of F-18-FDG PET/CT in differentiating benign from malignant adrenal tumors discovered either as adrenal incidentaloma or during staging or follow-up of oncologic patients. Data sources PubMed, EMBASE, Web of Science, and Cochrane Library were searched to select articles between 2000 and 2021. Study selection We included studies describing the diagnostic value of F-18-FDG PET/CT in adult patients with an adrenal tumor. Exclusion criteria were 10 or fewer participants, insufficient data on histopathology, clinical follow-up, or PET results. After screening of title and abstract by 2 independent reviewers, 79 studies were retrieved, of which 17 studies met the selection criteria. Data extraction Data extraction using a protocol and quality assessment according to QUADAS-2 was performed independently by at least 2 authors. Data synthesis A bivariate random-effects model was applied using R (version 3.6.2.). Pooled sensitivity and specificity of F-18-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 was 9.20 (95% CI, 5.27-16.08; P < .01). Major sources of heterogeneity (I-2, 57.1% [95% CI, 27.5%-74.6%]) were in population characteristics, reference standard, and interpretation criteria of imaging results. Conclusions F-18-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 cutoff values are needed.