.png){kind=small}
.png){kind=small}
BackTable / VI / Tool
Adrenal Washout Calculator for CT Scan
An adrenal washout calculator is a tool that helps to estimate the degree of adrenal gland function based on the results of a computed tomography (CT) scan. The adrenal glands are two small endocrine glands located on top of the kidneys that produce hormones that play important roles in various bodily functions. The adrenal CT washout calculator uses the results of a CT scan to calculate the percentage washout of the contrast material that is used during the scan. The contrast material is injected into a vein to help highlight certain structures in the body during the scan. The washout percentage is calculated by comparing the amount of contrast material in the adrenal gland at the beginning of the scan to the amount present at the end of the scan. The adrenal CT washout calculator is typically used to assess the function of the adrenal glands in patients who may have a problem with their adrenal gland function, such as adrenal insufficiency or Cushing's syndrome. It can also be used to monitor the effectiveness of treatment for these conditions. Calculate the adrenal washout based on CT attenuation below.
Adrenal Washout Calculator for CT Scan
Pre-contrast HU
60-75 Second Post-contrast HU
15 Minute Delayed HU
Value
Value
Adrenal Washout Formula
The adrenal gland washout calculator uses CT imaging data to measure the attenuation (density) of the adrenal lesion at different time points:
• Pre-HU: Pre-contrast (unenhanced) CT attenuation
• Post-HU: Enhanced (contrast) CT attenuation, typically taken 60-70 seconds after contrast administration
• Delayed HU: Delayed CT attenuation, usually taken 10-15 minutes after contrast administration
• Absolute Washout Percentage (AWP) = 100 x ((Post HU - Delayed HU) / (Post HU - Pre HU))
• Relative washout (RWP) = 100 x ((Post HU - Delayed HU) / (Post HU))
Interpreting Results
• Absolute percentage washouts greater than 60% suggests an adenoma.
• Relative percentage washouts greater than 50% suggets an adenoma.
• An adrenal lesion greater than 120 HU with washout shouldn't be diagnosed as an adenoma.
• Malignant lesions usually exhibit lower washout percentages, which suggests the need for more investigation.
What are Adrenal Nodules?
Adrenal nodules are abnormal growths on the adrenal glands, which sit atop your kidneys and produce hormones like cortisol, aldosterone, and adrenaline. Most adrenal nodules are noncancerous (benign) and found incidentally during imaging for something else (often called “adrenal incidentalomas”). Common types include:
• Adrenal adenoma: a benign tumor, often non-functioning.
• Pheochromocytoma: a tumor that secretes adrenaline-like hormones.
• Adrenal carcinoma: rare but malignant.
• Metastasis: cancer that has spread from somewhere else.
When an adrenal nodule is found, it is important to know if it is benign or not. CT washout measures how quickly a contrast dye is "washed out" of the adrenal nodule on CT scans over time. Benign adenomas tend to wash out contrast quickly, while malignant lesions tend to retain it longer. An adrenal nodule calculator is used to calculate the absolute washout percentage (AWP) and relative washout percentage (RWP).
Learn more on the BackTable VI Podcast
BackTable is a knowledge resource for physicians by physicians. Get practical advice on the Adrenal Washout Calculator for CT Scan and how to build your practice by listening to the BackTable VI Podcast, reading exclusing BackTable Articles, and following the work of our Contributors.
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
Related Podcasts
Articles
Adrenal Vein Sampling: Clinical Management Before & After
Adrenal Vein Sampling: Tips for Cannulating the Right Adrenal Vein
Topics
