RadteraCT Adrenal (Washout Protocol)
CT+ ContrastAbdomen & Pelvis
Indications
- Characterization of indeterminate adrenal nodule/mass (adenoma vs non-adenoma)
- Differentiation of lipid-poor adenoma from metastasis/other lesions
Patient prep
- 18-20G IV; check renal function
- NPO not strictly required; supine, arms up
- Identify target nodule from prior imaging to plan limited coverage
Contrast
Agentiodinated (iohexol 350 / iopamidol 370)
RouteIV
Dose~100-125 mL at 3-4 mL/s + saline chase
TimingNon-contrast first (HU measurement); enhanced at ~60-70 s (portal venous); delayed at 15 min for washout calculation
Technique
- Supine, arms up; limited coverage centered on adrenals (focused) or full abdomen if needed
- Three time points: non-contrast, ~60-70 s enhanced, 15-minute delayed
- 120 kV; thin/standard recon 2.5-3 mm through adrenals
- Place consistent ROI on the nodule across phases (avoid calcification/necrosis/edges) for HU and washout calculation
Series / Sequences
| # | Series / Sequence | Plane | Thickness | Notes |
|---|---|---|---|---|
| 1 | Non-contrast axial | axial | 2.5-3 mm | <=10 HU = lipid-rich adenoma |
| 2 | Enhanced (60-70 s) axial | axial | 2.5-3 mm | Portal venous HU |
| 3 | 15-min delayed axial | axial | 2.5-3 mm | Washout HU |
Key points
- Non-contrast HU <=10 = lipid-rich adenoma (no further phases needed)
- Absolute washout >=60% and relative washout >=40% indicate adenoma
- Absolute washout = (enhanced - delayed)/(enhanced - non-contrast) x100; relative = (enhanced - delayed)/enhanced x100
- Place identical ROIs across phases; avoid heterogeneous/calcified/necrotic regions
- Pheochromocytoma and some metastases can mimic washout—correlate clinically; biochemical screen before biopsy
References
• ACR Incidental Adrenal Mass White Paper
• ACR-SAR-SPR Practice Parameter for CT of the Abdomen
• Radiopaedia: adrenal washout CT ( link
• ACR-SAR-SPR Practice Parameter for CT of the Abdomen
• Radiopaedia: adrenal washout CT ( link
Source: Researched — verify against your institution
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Reference template — verify and adapt to your scanner, vendor and institution before clinical use. Not a substitute for clinical judgment.