Qué hace esta calculadora
Calculates the two commonly used CT washout formulas for an adrenal lesion.
Enter unenhanced, enhanced, and delayed attenuation in HU. The tool returns absolute and relative washout.
Antes del cálculo
- Confirm that unenhanced, enhanced, and delayed values come from the same lesion and a valid washout protocol.
- Place comparable regions of interest in homogeneous tissue, avoiding necrosis, hemorrhage, calcification, and surrounding structures.
Alcance clínico
Use the formulas to characterize an enhancing adrenal mass on a dedicated CT protocol that includes unenhanced, enhanced, and delayed attenuation measurements from comparable regions of interest.
Aplicabilidad y exclusiones
- Do not calculate washout when the required phases are absent, measurements are not comparable, or a denominator is zero.
- Hemorrhage, calcification, necrosis, marked heterogeneity, and protocol timing can invalidate or limit threshold interpretation.
Método y lógica de cálculo
Absolute washout uses all three phases; relative washout uses enhanced and delayed attenuation. Negative values indicate delayed enhancement rather than washout. Published thresholds depend on acquisition timing and population.
Absolute washout = (enhanced HU - delayed HU) / (enhanced HU - unenhanced HU) × 100Relative washout = (enhanced HU - delayed HU) / enhanced HU × 100Tabla de interpretación
| 15-minute result | Traditional interpretation |
|---|---|
| Absolute washout ≥60% | Supports an adenoma in the appropriate protocol |
| Relative washout ≥40% | Supports an adenoma in the appropriate protocol |
| Below threshold or negative | Indeterminate; not diagnostic of malignancy |
Errores frecuentes
- Combining attenuation values from different examinations, lesions, phases, or noncomparable regions of interest.
- Applying a washout threshold to a heterogeneous lesion or treating it as definitive proof of an adenoma.
Washout is one characterization feature. Current adrenal guidance gives it limited evidentiary weight and requires morphology and clinical context.
Ejemplo práctico
Caso: Fictional example: unenhanced 30 HU, enhanced 100 HU, and 15-minute delayed 50 HU.
Cálculo: Absolute: (100-50)/(100-30) × 100 = 71.4%. Relative: (100-50)/100 × 100 = 50%.
Interpretación: Both values exceed traditional 15-minute thresholds, but morphology, protocol quality, prior imaging, and the complete adrenal workup remain decisive.
Cómo usar esta calculadora
- Completa los campos visibles de imagen y medición. Los datos obligatorios están indicados en la herramienta.
- Revisa la categoría, la puntuación, las mediciones y cualquier recomendación o advertencia calculada.
- Copia el texto para el informe solo después de comprobar el resultado con la exploración completa y la guía de referencia.
Preguntas sobre esta calculadora
What happens if a denominator is zero?
That formula is undefined and must not be reported as a percentage.
Does sub-threshold washout diagnose malignancy?
No. It is indeterminate and must be interpreted with morphology, history, other imaging, and appropriate biochemical evaluation.
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