Adrenal Washout Calculator

Adrenal Washout Calculator is a radiological tool used to analyze CT scan measurements (in Hounsfield units, or HU) of adrenal masses to determine if they are benign or potentially malignant.

Uses density measurements from three phases of an adrenal-protocol CT scan:

Delayed Phase: Scans taken 15 minutes after the contrast was injected.
Unenhanced Phase: The initial scan before contrast is given.
Portal Venous Phase: Scans taken roughly 60–75 seconds after contrast injection.

Adrenal Washout

CT Characterization of Adrenal Masses

1. Non-Contrast (Unenhanced)

HU

If ≤ 10 HU, lesion is likely lipid-rich.

2. Enhanced (Portal Venous)

HU

Typically 60–70 seconds post-injection.

3. Delayed (15 Minutes)

HU

Diagnosis

—

Absolute (AWO)

–%

Threshold: ≥ 60%

Relative (RWO)

–%

Threshold: ≥ 40%

Calculation assumes standard adrenal CT protocol.
Clinical correlation required.

Disclaimer

While Adrenal washout calculator is highly effective, they have to be used as a supplementary tool alongside clinical judgment and other medical imaging.