🫘 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.
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
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Unenhanced HU (leave blank if none; RPW only) | 25 |
|---|---|
| Enhanced HU (portal venous, 60–70 s) | 90 |
| Delayed HU (15 min) | 45 |
→AssessmentConsistent with adenoma
- Absolute washout APW：69.2% (threshold ≥60%) = (E−D)/(E−U)
- Relative washout RPW：50.0% (threshold ≥40%) = (E−D)/E
- Washout read：Meets threshold (APW ≥60% or RPW ≥40%)
Frequently asked questions
- What is 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.
- How is Adrenal Nodule Washout (APW / RPW) calculated? What is the core formula?
- 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.
- When is Adrenal Nodule Washout (APW / RPW) used?
- 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.
- What are the key clinical points for Adrenal Nodule Washout (APW / RPW)?
- 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.
- What are the limits and cautions when using Adrenal Nodule Washout (APW / RPW)?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is Adrenal Nodule Washout (APW / RPW) calculated in practice? Can you show a worked example?
- Inputs: Unenhanced HU (leave blank if none; RPW only) 25, Enhanced HU (portal venous, 60–70 s) 90, Delayed HU (15 min) 45 → Result: Assessment Consistent with adenoma（Absolute washout APW: 69.2% (threshold ≥60%) = (E−D)/(E−U), Relative washout RPW: 50.0% (threshold ≥40%) = (E−D)/E, Washout read: Meets threshold (APW ≥60% or RPW ≥40%)）