🫘 Adrenal Nodule Washout (APW / RPW)
Turn adrenal washout into a tool: enter unenhanced/enhanced/delayed HU to compute APW and RPW, flag adenoma at APW ≥60% or RPW ≥40%, and reconcile with the unenhanced-HU context. Instant, browser-side.
Clinical takeaway
APW = (E−D)/(E−U)×100, threshold ≥60%.
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When to use
Characterizing adrenal incidentalomas (unenhanced > 10 HU, or no unenhanced series): adenoma (incl. lipid-poor) vs lesions needing further workup. HU measurement is done by the radiologist.
How it works
APW = (E−D)/(E−U)×100 (needs unenhanced); RPW = (E−D)/E×100 (used when no unenhanced). Thresholds: APW ≥60% or RPW ≥40% suggests adenoma.
Key points
- APW = (E−D)/(E−U)×100, threshold ≥60%.
- RPW = (E−D)/E×100, threshold ≥40% (use when no unenhanced series).
- Unenhanced ≤10 HU → lipid-rich adenoma, washout unnecessary.
- Unenhanced > 43 HU → concerning for malignancy; do not call adenoma on washout alone.
- Pheochromocytoma / hypervascular metastases can be false-positive; less reliable for ≥4 cm or heterogeneous nodules.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.