- Most adenomas can be characterized as lipid rich on precontrast scan, which will show attenuation value of less than 10 HU
- Some adenomas are lipid poor, therefore demonstrate a higher attenuation value. This can be further characterized by performing an adrenal mass CT protocol
- Adrenal mass CT consists of 1) precontrast, 2) portovenous phase postcontrast (60-70 sec) and 3) delayed phase (10-15 min)
- Measurement of region of interests (ROI) over > half of the mass at different phases. Values are used to calculate absolute and relative percentage washout
- APW > 60% OR
- RPW > 40%
Johnson PT, Horton KM, Fishman EK. Adrenal imaging with multidetector CT: evidence-based protocol optimization and interpretative practice. RadioGraphics 2009;29:1319-1331.