Adrenal Washout Calculator
Calculate the adrenal washout percentage to help differentiate between benign and malignant adrenal masses based on CT attenuation values.
Published by:
isCalculator Editorial Team
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How to Use the Adrenal Washout Calculator
This calculator helps assess adrenal lesions by computing absolute and relative washout percentages from CT attenuation values (Hounsfield Units, HU). Follow these steps:
- Enter Pre-Contrast (HU): Input the attenuation value from the non-contrast phase.
- Enter Post-Contrast (HU): Input the value from the portal venous phase (60–70 seconds delay).
- Enter Delayed Contrast (HU): Input the value from the delayed phase (10–15 minutes delay).
- Click "Calculate Washout": The results will display absolute washout, relative washout, and an interpretation.
- Absolute washout > 60%: Likely benign (e.g., adenoma).
- Absolute washout 40–60%: Indeterminate.
- Absolute washout < 40%: Suspicious for malignancy.
Interpretation Guide:
Note: All values must be in HU. The calculator will show an error if post-contrast equals pre-contrast or is zero (prevents division by zero).
Previous Results
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Frequently Asked Questions
Adrenal washout refers to the percentage decrease in CT attenuation (HU) of an adrenal mass from the post-contrast phase to the delayed phase. It helps differentiate benign adenomas (high washout) from malignant lesions (low washout).
Absolute washout > 60% or relative washout > 40% at 10-15 minutes suggests a benign adenoma. Lower values raise suspicion for malignancy.
If post-contrast equals pre-contrast, the absolute washout formula has a zero denominator. This may indicate a non-enhancing mass; clinical correlation is needed.
