"In clinical practice therefore, 10 HU is the most widely used threshold value for the diagnosis of lipid-rich adrenal adenoma."

Adrenal Imaging
Blake MA et al.
AJR 2010; 194:1450-1460

"In conclusion the 10 minute delayed adrenal enhancement washout tests have reduced sensitivity for the detection of adenomas compared with results from prior studies, and the test sensitivity appears to be clinically suboptimal. This finding might be explained by insufficient time for the intravenous contrast material to wash out from benign lesions."

Incidental Adrenal Lesions: Accuracy of Characterization with Contrast-enhanced Washout Multidetector CT—10-minute Delayed Imaging Protocol Revisited in a Large Patient Cohort
Sangwaiya MJ et al.
Radiology 2010; 256:504-510

"Ten minute delayed multidetector CT adrenal washout tests have reduced accuracy compared with results from prior studies; overall test accuracy at 40% threshold was 77.7% according to our test results."

Incidental Adrenal Lesions: Accuracy of Characterization with Contrast-enhanced Washout Multidetector CT—10-minute Delayed Imaging Protocol Revisited in a Large Patient Cohort
Sangwaiya MJ et al.
Radiology 2010; 256:504-510

Incidental Adrenal Lesions: Accuracy of Characterization with Contrast-enhanced Washout Multidetector CT—10-minute Delayed Imaging Protocol Revisited in a Large Patient Cohort
Sangwaiya MJ et al.
Radiology 2010; 256:504-510

"The high diagnostic accuracy leads to a decrease in the number of patients with an indeterminate adrenal mass, which requires the other diagnostic methods including MR imaging, radionuclide imaging, and adrenal biopsy."

Distinguishing Adrenal Adenomas from Nonadenomas: Combined Use of Diagnostic Parameters of Unenhanced and Short 5-minute Dynamic Enhanced CT Protocol
Kamiyama T et al
Radiology 2009; 250:474-481