Adrenal Washout Calculator
Calculate adrenal washout from CT imaging to diagnose adrenal adenomas
CT Scan Measurements
Non-contrast CT scan measurement
Contrast-enhanced scan at 60-75 seconds
Delayed scan at 15 minutes post-contrast
Results
Enter CT scan measurements to calculate adrenal washout
Calculation Formulas
Absolute Washout: 100 × [(Post HU - Delayed HU) / (Post HU - Pre HU)]
Relative Washout: 100 × [(Post HU - Delayed HU) / Post HU]
Enhancement: Post HU - Pre HU
Reference Values
Adenoma Criteria
- • Absolute washout 60%+
- • Relative washout 40%+
- • Pre-contrast HU under 10 (lipid-rich)
Exclusion Criteria
- • Post-contrast HU 120+
- • Pre-contrast HU 43+
- • Inhomogeneous lesions
- • Necrosis or hemorrhage
CT Protocol
- • Non-contrast phase
- • Post-contrast: 60-75 sec
- • Delayed: 15 minutes
Clinical Notes
Adenomas wash out contrast rapidly due to their vascular architecture
Pheochromocytomas may also show washout but rarely have lipid content
Hypervascular metastases may reduce washout specificity
Both absolute and relative washout provide complementary information
WARNING: Important Medical Disclaimer
This calculator is designed for healthcare professionals familiar with adrenal imaging interpretation. It provides mathematical calculations based on established washout criteria but should not replace clinical judgment or comprehensive radiological assessment.
For Healthcare Professionals Only: Results should be interpreted in the context of complete clinical history, physical examination, laboratory values, and comprehensive imaging findings. Consider additional imaging modalities (MRI, FDG-PET) when washout characteristics are indeterminate.
Not for Patient Self-Assessment: This tool requires specialized medical training to interpret. Patients should discuss results with their radiologist or endocrinologist for proper clinical correlation and management recommendations.
Understanding Adrenal Washout
What is Adrenal Washout?
Adrenal washout is a CT imaging technique used to differentiate benign adrenal adenomas from malignant lesions. It measures how quickly contrast material washes out of an adrenal lesion over time.
Clinical Significance
Benign adenomas typically show rapid contrast washout due to their rich blood supply and specific cellular characteristics, while malignant lesions tend to retain contrast longer.
Imaging Protocol
- 1.Non-contrast phase: Baseline tissue attenuation
- 2.Post-contrast (60-75s): Peak enhancement
- 3.Delayed (15 min): Washout assessment
Interpretation Guidelines
Adenoma Characteristics
- • Absolute washout 60%+
- • Relative washout 40%+
- • Homogeneous enhancement
- • Well-defined margins
Concerning Features
- • Pre-contrast HU 43+
- • Post-contrast HU 120+
- • Poor washout characteristics
- • Irregular enhancement
Limitations
Washout analysis may be less reliable in patients with hypervascular primary tumors (renal cell carcinoma, hepatocellular carcinoma) due to hypervascular metastases that can mimic adenoma washout patterns.