Measuring visceral adipose tissue content from contrast enhanced computed tomography

Area of Science:

• Radiology and Imaging Science
• Medical Physics

Background:

• Accurate quantification of visceral adipose tissue (VAT) is crucial for understanding its role in various diseases.
• Routine contrast-enhanced computed tomographic (CT) scans are widely available, offering a potential source for retrospective VAT assessment.
• Minimizing radiation exposure is a key consideration in medical imaging protocols.

Purpose of the Study:

• To determine if visceral adipose tissue (VAT) content can be reliably quantified retrospectively from contrast-enhanced CT studies.
• To evaluate the feasibility of avoiding additional radiation exposure for VAT measurement.
• To enable large-scale epidemiological studies on VAT in relation to different diseases.

Main Methods:

• Seven patients underwent CT scans.
• Visceral adipose tissue (VAT) content was quantified from both unenhanced and contrast-enhanced CT images.
• Measurements were performed within a specific Hounsfield Unit (HU) range (-150 to -50 HU).

Main Results:

• Measured VAT volume was significantly smaller in enhanced images compared to unenhanced images (p = 0.016), likely due to partial volume effects.
• A validated formula (VAT_unenhanced = 1.11 x VAT_enhanced + 2.95, p = 0.0001) was derived for converting enhanced VAT measurements to unenhanced equivalents.
• Adjusting the upper density limit for VAT in enhanced images can compensate for the effects of intravenous contrast media.

Conclusions:

• Retrospective quantification of visceral adipose tissue (VAT) from routine abdominal CT images is feasible.
• The influence of intravenous contrast administration on VAT measurements must be carefully considered and accounted for.
• This approach can facilitate epidemiological research without requiring extra radiation exposure.