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

Application of dual-energy CT in characterization of adrenal nodules has not been well evaluated.

To evaluate the ability of dual-energy CT scan to differentiate an adrenal adenoma from a metastasis.

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.

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.

Unique energy spectrum information provided by dual-energy CT scan displays a high capacity to distinguish adrenal adenoma from metastasis.