CT features and their diagnostic values for adrenal pheochromocytoma versus adrenal cortical adenoma

Objective To analyze and compare CT features of adrenal pheochromocytoma versus adrenal cortical adenoma,and improve the diagnosis accuracy. Methods From January 2008 to January 2018,clinical data about patients diagnosed as adrenal space-occupying lesions in the endocrinology department of the first medical center of Chinese PLA General Hospital were retrospectively analyzed.According to pathological results,patients were divided into adrenal pheochromocytoma group and adrenal cortical adenoma group.The CT imaging data including tumor location,density,diameter,plain CT value and enhanced CT value were compared between the two groups.ROC curves were established to examine the diagnostic value of each indicator. Results Of the 108 cases in the pheochromocytoma group,there were 46 males and 62 females,with an average age of 47.92±1.45 years.Of the 50 cases with cortical adenoma,there were 24 males and 26 females,with an average age of 48.28±1.77 years;There was no significant difference in age and sex between the two groups.However,BMI of the pheochromocytoma group was significantly lower than that of the cortical adenoma group （23.89±0.37 kg/m² vs 25.76±0.54 kg/m²,P<0.001）.Most pheochromocytoma （63.8%） was found in the left side and most cortical adenoma （56%） was in the right side （P=0.001）.The volume of the pheochromocytoma was significantly larger than that of the cortical adenoma （6.46±0.24 cm vs 4.55±0.28 cm,P<0.001）.Both plain and enhanced CT values （HU） of the pheochromocytoma were greater than those of the cortical adenoma （32.26±2.07 vs 12.11±4.25,58.57±3.62 vs 40.35±5.10,P<0.05,respectively）.ROC analysis revealed a threshold of 5.05 cm for tumor diameter in the diagnosis of pheochromocytoma （AUC 0.744,sensitivity 70.21%,specificity 67.59%）;threshold of 17.5 HU for CT value （AUC 0.823,sensitivity 96.3%,specificity 58.3%）;and threshold of 48.5 HU for enhanced CT value （AUC 0.696,sensitivity 85.7%,specificity 64.7%）.The combinations of the three indicators or the plain CT value and the enhanced CT value had better diagnostic efficiency,with sensitivity of 100.0% for both,and specificities of 90.9% and 84.6%,respectively,which were superior to each of the single indicator. Conclusion For adrenal space-occupying lesions,patient's with BMI<24 kg/m²,tumor on the left,tumor diameter>5.05 cm,plain CT value>17.5 HU and enhanced CT value>48.5 HU are more likely to be diagnosed as pheochromocytoma.The diagnostic efficiency of combined application of indicators is better than the single indicators.