Input Values
Enter CT attenuation values (Hounsfield units) from all three phases
Important Disclaimer
This tool is for educational purposes only. Clinical decisions should be made by qualified healthcare professionals considering all relevant clinical information.
About Adrenal Washout
Adrenal washout analysis on CT is used to characterize adrenal lesions, particularly to differentiate lipid-poor adenomas from non-adenomatous lesions.
Absolute washout: Calculated using pre-contrast, portal venous, and delayed images. A value ≥60% is consistent with an adenoma.
Relative washout: Used when pre-contrast images are unavailable. A value ≥40% is consistent with an adenoma.
Clinical Background
Adrenal lesions are common incidental findings on abdominal CT scans, with a prevalence of approximately 4-5% in the general population. The primary goal of adrenal imaging is to distinguish benign from malignant lesions, with adrenal adenomas being the most common benign adrenal tumor.
Technical Considerations
The adrenal washout protocol typically includes:
- Non-contrast CT (pre-contrast)
- Portal venous phase (60-70 seconds post-contrast)
- Delayed phase (15 minutes post-contrast)
Adenomas typically demonstrate rapid contrast washout due to their rich blood supply and lack of a substantial extracellular space, while malignant lesions tend to retain contrast due to their irregular vascularity and larger extracellular space.
Interpretation Guidelines
| Lesion Type | Absolute Washout | Relative Washout |
|---|---|---|
| Adenoma | ≥60% | ≥40% |
| Non-adenoma | <60% | <40% |