Malignancy Risk Stratification in FDG-PET Avid Adrenal Lesions: Diagnostic Utility and Predictive Factors

Area of Science:

• Nuclear Medicine
• Radiology
• Oncology

Background:

• Fluorodeoxyglucose positron emission tomography (^18FFDG PET) is used for adrenal lesion assessment.
• Variability in reporting and wide SUVmax ranges limit its routine diagnostic utility.
• This study sought to define FDG-PET thresholds for improved malignancy risk stratification.

Purpose of the Study:

• To evaluate the utility of ^18FFDG PET in stratifying malignancy risk of adrenal lesions.
• To establish diagnostic thresholds for FDG-avid adrenal lesions.

Main Methods:

• Retrospective multi-center cohort study of 104 adrenalectomies with pre-operative ^18FFDG PET.
• Independent and blinded re-reporting of imaging parameters including SUVmax, SUVmean, and Hounsfield Units (HU).

Main Results:

• Malignancy was confirmed in 65.4% of cases.
• Mean SUVmax was significantly higher in malignant (10.6) vs. benign (4.7) lesions (p<0.001).
• An SUVmax cut-off of 5.63 demonstrated 75% sensitivity and 19.4% false-positive rate for malignancy. SUVmax ≥ 5.63 was independently predictive of malignancy (OR 6.0).

Conclusions:

• ^18FFDG PET, with established thresholds (SUVmax ≥ 5.63, HU ≥ 20), serves as a valuable adjunct for adrenal lesion malignancy risk stratification.
• Consideration of ^18FFDG PET is recommended for large, suspicious adrenal lesions or in patients with a history of malignancy.