The Diagnostic Value Of CT Histogram Analysis In Characterization Of Lipid-poor Adrenal Cortical Adenomas

Objective:To evaluate the diagnostic value of CT histogram analysis in characterization of lipid-poor adenomas.Materials and Methods:A total of192adrenal masses in184patients were confirmed either histopathology or by means of following up for at least12months, including97lipid-rich adenomas,47lipid-poor adenomas and48nonadenomas. Unenhanced CT attenuations were measured on every mass and the negative pixel percentages were calculated by CT histogram analysis; receiver operating characteristic curve analysis was performed to choose the optimal cut-off value to differentiate between lipid poor cortical adenomas and nonadenomas.Result:There was no statistical difference between lipid-poor adenomas (mean24.90±9.58HU) and nonadenomas (35.48±8.37HU) on unenhanced CT attenuation (P>0.05), however, lipid-poor adenomas (n=47, mean19.49±10.31%) showed significantly higher (t=11.55, P=0.000) negative value percentages than that of nonadenomas (n=48, mean1.89±2.23%). All31lipid-poor adenomas with CT attenuations between10HU-30HU had a negative pixel percentage over10%, only8of15lipid-poor adenomas with CT attenuations above30HU had a negative pixel percentage above10%。The sensitivity and specificity of diagnosing lipid-poor adenomas were60%and100%at a threshold of negative value percent15%。 At a threshold of10%and5%, the sensitivity was increase to79.2%and95.8%, but the specificity was decrease to98%and94%respectively.The sensitivity and specificity of diagnosing adenomas were67%and100%at a threshold of Unenhanced CT attenuations were measured10HU。Conclusion:CT histogram analysis could help to improve diagnostic accuracies of CT densitometry in characterization of lipid-poor adenomas, especially for lipid-poor adenomas with unenhanced CT attenuations between10HU to30HU.