Dual-energy CT: clinical application in differentiating an adrenal adenoma from a metastasis

Abstract

Background Application of dual-energy CT in characterization of adrenal nodules has not been well evaluated. Purpose To evaluate the ability of dual-energy CT scan to differentiate an adrenal adenoma from a metastasis. Material and Methods Fifty-five patients presenting 63 adrenal nodules underwent dual-energy CT scan at tube voltages of 80 kVp and 140 kVp. Mean attenuation values were measured for every nodule at 80/140 kVp and at 40/100 keV. Mean attenuation value changes between 140 kVp and 80 kVp (MAVC140–80kVp) and mean attenuation value changes between 100 keV and 40 keV (MAVC100–40keV) were calculated. Results Of the 63 adrenal nodules available for analyses, 42 nodules were classified as adenoma (26 lipid-rich and 16 lipid-poor) and 21 were classified as metastases. MAVC140–80kVp and MAVC100–40keV of all adenomas (including lipid-poor and lipid-rich) were significantly higher than metastases ( P < 0.001). According to receiver-operating characteristic (ROC) curve analyses, areas under the ROC curve of MAVC140–80kVp and MAVC100–40keV for diagnosing adrenal adenomas were both of 0.964. When the cut-off points were set at 2.42 HU and 6.95 HU for MAVC140–80kVp and MAVC100–40keV, the two parameters both had a sensitivity of 78.6% and a specificity of 100% in adenoma diagnosis. Conclusion Unique energy spectrum information provided by dual-energy CT scan displays a high capacity to distinguish adrenal adenoma from metastasis.