The diagnostic value of native and early post-contrast CT attenuation in differentiating benign from potentially malignant adrenal lesions.

PURPOSE: Adrenal gland lesions are increasingly detected as incidental findings during standard abdominal CT examinations. The aim of this study was to evaluate the diagnostic utility of native and early post-contrast (1-min) CT attenuation values, as well as lesion size, in differentiating benign from potentially malignant adrenal lesions, and to determine optimal cut-off values for these parameters in a routine clinical setting.

METHODS

An observational, historical cohort study included 50 patients who underwent adrenalectomy between 2012 and 2024, with available preoperative CT imaging. Based on histopathology, patients were classified as having benign or potentially malignant lesions. Native and 1-min postcontrast attenuation values in Hounsfield units, along with maximal lesion diameter, were obtained from preoperative scans. Demographic and clinical data were obtained from the institutional database. Statistical analysis included Mann-Whitney U and chi-squared tests, ROC curve analysis, and logistic regression.

RESULTS

Potentially malignant lesions demonstrated significantly higher native attenuation, 1-min postcontrast attenuation, and larger size. ROC analysis identified optimal cut-offs of 15 HU (native), 59 HU (1-min postcontrast), and 4.2 cm (size). In univariate analysis, all three parameters were significantly associated with malignancy (p < 0.05). However, in multivariate analysis, only the 1-min postcontrast attenuation remained an independent predictor (p = 0.019).

CONCLUSION

Native and early postcontrast attenuation values differentiate benign from potentially malignant adrenal lesions, with the 1-min postcontrast phase showing the highest diagnostic accuracy. Multivariate analysis confirmed the 1-min postcontrast value as the only independent predictor of malignancy. These findings support the clinical utility of early-phase imaging in guiding management decisions and surgical planning.