Differential diagnosis of adrenal metastasis and lipid-poor adrenal adenoma with CT

Abstract

Objective To study the CT characteristics of adrenal metastasis (AM) and lipid-poor adrenal adenoma (Lp-AA) . Methods We retrospectively analyzed clinical and CT dates of AM (n=25) and Lp-AA (n=61) which were pathologically or clinically confirmed. The size, location, number, contour, cystic degeneration, cal-cification, hemorrhage and the clinical data were analyzed, as well as, CT value of tumor were measured and calcu-lated. Receiver operating characteristic (ROC) curves were employed to assess the significant continuous variables to tell AM from Lp-AA. Results 34 adrenal lesions were detected for 25 cases of AM (9 case showed bilateral with 18 lesions) . There were 65 lesions for 61 cases of Lp-AA (3 cases showed bilateral and 1case showed two lesions in unilateral side) . Sex and age had significant difference between the two groups (P 0.05) . For the con-tinuous variables, plain scan CT value, enhancement amplitude, relative percentage washout (RPW) and tumor size had significant difference between the two groups (P 30.4 HU, area under ROC curve, sensitivity and specificity were 0.878, 91.2%, and 72.3%, re-spectively. When RPW was >-33.4%, the area under ROC curve, sensitivity and specificity were 0.643, 79.4%,64.7%, respectively. When the maximum and minimum diameter of tumor were >2.9 cm and 2.2 cm respectively, the area under the curve, sensitivity, specificity were 0.762, 73.5%, 75.4% and 0.706, 64.7%, 69.2%, respectively. When venous phase increase and the largest increase were <37.7 HU and 37.3 HU respectively, the area under the curve, sensitivity, specificity were 0.805, 89.2%, 64.7% and 0.833, 95.4%, 64.7% respectively. Conclusion Tu-mor size, number, contour, cystic degeneration, CT measured and calculated value, as well as the patients’clinical data are of great value in differentiating AM and Lp-AA. Key words: Adrenal tumor; Metastasis; Lipid-poor adenoma; Differential diagnosis; Tomography; X-ray computed