Abstract：Objective: To evaluate the diagnostic value of CT histogram analysis in the characterization of lipid-poor adrenal adenomas. Methods: A total of 192 adrenal masses in 184 patients were confirmed either by histopathology or by following up for at least 12 months, including 97 lipid-rich adenomas, 47 lipid-poor adenomas and 48 nonadenomas. Unenhanced CT attenuation was measured on every mass and the percentage of negative pixel was calculated by CT histogram analysis. Receiver operating characteristic curve analysis was performed to choose the optimal cut-off value to differentiate between lipid-poor adenomas and nonadenomas. Result: There was no statistical difference of unenhanced CT attenuation between lipid-poor adenomas (mean (24.90±9.58) HU) and nonadenomas (35.48±8.37) HU(P＞0.05), however, lipid-poor adenomas (n=47，mean (19.49±10.31)%) showed significantly higher(t=11.55, P=0.000) negative value percentage than nonadenomas (n=48，mean (1.89±2.23)%). All 31 lipid-poor adenomas with CT attenuations between 10 HU to 30 HU had a negative pixel percentage over 10%. Only 8 of 15 lipid-poor adenomas with CT attenuations above 30 HU had a negative pixel percentage above 10%. At a cut-off value of 10%, the sensitivity and specificity of calculated negative value percentage to diagnose lipid-poor adenomas were 80.9% and 97.9% respectively. Conclusion: CT histogram analysis can help to improve diagnostic accuracy of CT densitometry in characterization of lipid-poor adenomas, especially lipid-poor adenomas with unenhanced CT attenuations between 10 HU to 30 HU.
2013, Vol. 24 
