Adrenal Washout Calculator

CT characterization of adrenal masses - adenoma vs non-adenoma differentiation

Attenuation Values (HU)

Unenhanced (Pre-contrast)

Leave empty if not available - relative washout will be calculated

Enhanced (60-70s)

Portal venous phase

Delayed (15 min)

15-minute delayed phase

Pheochromocytoma Risk Assessment

Optional - helps identify potential pheochromocytoma mimicking adenoma

Arterial Phase HU

Size (cm)

Necrosis or cystic change Present in 73% of pheochromocytomas vs 30% of adenomas Clinical symptoms Hypertension, headache, palpitations, sweating

About Adrenal Washout

Formulas

Absolute Washout:
[(Enhanced - Delayed) / (Enhanced - Unenhanced)] × 100

Relative Washout:
[(Enhanced - Delayed) / Enhanced] × 100

Thresholds

Absolute washout ≥60% = Benign adenoma
Relative washout ≥40% = Benign adenoma
Unenhanced ≤10 HU = Lipid-rich adenoma

⚠️ Pheochromocytoma Warning

Up to 43% of pheochromocytomas can meet adenoma washout criteria. Lesions with enhanced HU >130 have 100% rapid washout mimicking adenoma. Always consider biochemical workup before biopsy.

References

Caoili EM, et al. Radiology. 2002;222(3):629-633.
Korobkin M, et al. AJR. 1998;170(3):747-752.
Blake MA, et al. AJR. 2016 - Pheochromocytoma washout patterns.
Boland GW, et al. AJR. 1998;171(1):201-204.