OBJECTIVE To identify radiologic features that correlate with mild autonomous cortisol excess using planar and volumetric analysis.

DESIGN Cross-sectional study.

METHODS In the study, 64 patients with overt Cushing syndrome (CS), 59 patients with mild autonomous cortisol excess (MACE), and 64 patients with nonfunctioning adrenal tumors (NFAT) with evaluable CT scans were included. Patients with NFAT and MACE were BMI-matched with those with overt CS. Planar and volumetric analyses of CT scans were performed in DICOM images using OsiriX software.

RESULTS The mean age was 56.6 ± 1.01 years, and 123 patients (65.1%) were female. In the order of NFAT, MACE, and overt CS, the diameters and volumes of the adenoma increased, while limb widths and volumes of the contralateral adrenal gland decreased. Patients with MACE or overt CS were more likely to have osteoporosis than those with NFAT (P = 0.006), and patients with overt CS were more likely to experience a fragility fracture than those with NFAT or MACE (P = 0.002). Among radiologic features, the limb width of the contralateral adrenal gland correlated with the cortisol level after overnight dexamethasone suppression test (r = -0.583, P < 0.001).

CONCLUSIONS The study showed that the contralateral adrenal limb thinning was a distinctive radiologic feature of autonomous cortisol excess in the planar and volumetric analysis.