Purpose: To retrospectively compare computed tomography (CT) sensitivities of large (≥3 cm) adenoma and cortical carcinoma.
Methods: Between January 2004 and November 2012, 43 non-oncologic patients with 43 adrenal masses [31 large adenomas, and 12 carcinomas] underwent unenhanced CT, early contrast-enhanced CT, and delayed contrast-enhanced CT scans prior to adrenalectomy. Three types of region-of-interest (ROI) were used on early contrast-enhanced CT images:aROI (large ROI) covering more than half of a mass and two small ROIs fitted to the highest (high ROI) or lowest (low ROI) attenuation area. These ROIs were also placed in the same area on the other CT images. Adenoma was diagnosed if a mass measured ≤10 HU on unenhanced CT image, or if it had ≥60% absolute percentage washout (APW)or ≥40% relative percentage washout (RPW).Carcinoma was diagnosed if a mass had <60% APW and <40% RPW. CT sensitivities for large adenoma and carcinoma were compared.
Results: CT sensitivities for large adenoma vs. carcinoma were 64.5% (20/31) vs. 100% (12/12) using a large ROI, 100% (31/31) vs. 50.0% (6/12) using a high ROI, and 51.6% (16/31) vs. 100% (12/12) using a low ROIs, respectively.
Conclusions: CT sensitivities for large adenoma and cortical carcinoma are influenced by the size or location of an ROI.A large ROI helps to minimize loss of CT sensitivity for large adenoma and to detect carcinoma.