A Crucial Step Adjunct to CT Attenuation Values In Characterizing Adrenal Masses A Prospective Observational Study At Our Institute.

ABSTRACT

Aim: To characterize incidentally detected adrenal masses by CT attenuation values and 15 minutes wash out characteristics at contrast-enhanced CT. Method: Prospective observational study from March 2012 -2013 was done, with all the abdominal scan evaluated for adrenal masses. Departmental protocol was followed with15 minutes delayed scan added. CT attenuation values at different phases were used to calculate absolute percentage washout (APW) and relative percentage washout (RPW). The masses with attenuation value <10HU on unenhanced scans were diagnosed as lipid rich adenomas and masses with attenuation values >10 on plain scan with APW of >60% and RPW>40% were diagnosed as lipid poor adenomas; rest being nonadenomas, metastasis if there was known malignancy. The masses were evaluated in terms of their sizes, site of involment, stastical significance (p<0.05) in attenuation values at different phases and washout studies. Results: 96 lesions were detected in 84 patients from March 2012 -2013.MF ratios of 1.71, mean age being 46 years. Lipid poor adenomas (LPA) were the commonest mass followed by metastasis. 64% of patients with malignancy had adrenal metastasis while 36% had adenomas. There was no significant difference in size(p=0.23) between LPA and non-adenomas (NA) whereas statistical difference was noted in mean attenuation values on unenhanced, delayed, wash-in and wash-out values(p <0.05).There was no significant difference on enhanced scan (p=0.95),but absolute percentage washout (APW) and relative percentage washout (RPW) was statistically significant between LPA and NA (p<0.05).Conclusion: CT attenuation values, absolute and relative percentage washout values characterize the adrenal masses.