From the Guidelines
The best radiologic evaluations for visceral adiposity are computed tomography (CT) and magnetic resonance imaging (MRI), with CT being considered the gold standard. These imaging techniques allow for precise quantification of visceral fat by distinguishing it from subcutaneous fat. CT scans at the level of L4-L5 vertebrae provide accurate measurements of visceral fat area, while MRI offers similar accuracy without radiation exposure 1.
Some key points to consider when evaluating visceral adiposity using radiologic methods include:
- CT and MRI are considered the "gold standard" for assessing visceral adiposity due to their ability to distinguish between subcutaneous and visceral fat 1.
- Dual-energy X-ray absorptiometry (DXA) is a less expensive alternative that estimates visceral fat with moderate accuracy, although it cannot differentiate between subcutaneous and visceral fat 1.
- Ultrasound can also be used to measure visceral fat thickness, particularly at the preperitoneal area, though it is less precise than CT or MRI.
- The choice of imaging method depends on the clinical setting and the need for precise quantification of visceral fat.
In terms of the clinical significance of visceral adiposity, it is more metabolically active than subcutaneous fat and is strongly associated with cardiometabolic diseases, insulin resistance, and inflammation. Therefore, accurate assessment of visceral adiposity is crucial for risk stratification and management of these conditions. For routine clinical practice, a single-slice CT or MRI at the L4-L5 level is typically sufficient, while research settings may utilize volumetric measurements from multiple slices 1.
From the Research
Radiologic Evaluations for Visceral Adiposity
The best radiologic evaluations for visceral adiposity include:
- Computed Tomography (CT) scan analysis, which can provide precise and reproducible results for measuring visceral fat area (VFA), subcutaneous fat area (SFA), total fat area (TFA), and visceral-to-subcutaneous fat ratio (V/S ratio) 2
- Magnetic Resonance Imaging (MRI), which can be used to estimate visceral fat content, but single-slice MRI methods may lead to inconsistencies in the estimation of intra-abdominal fat content 3
- Dual-energy X-ray absorptiometry (DXA), which can be used to assess total and regional body composition, including visceral adiposity, but requires careful review of the manufacturer's auto analysis and consistency in conducting serial scans to ensure accurate and precise measures 4
Measurement Sites and Protocols
The choice of measurement site and protocol can affect the accuracy of visceral adiposity measurements:
- Multi-slice CT protocols may provide a more complete assessment of abdominal fat stores and distribution than single-slice assessments 5
- VAT area measurement at a single level, such as 3 cm above the lower margin of L3, can reflect changes in VAT volume and body weight 6
- The use of single-slice imaging techniques can lead to inconsistencies in the estimation of intra-abdominal fat content, and may not be suitable for accurate determination of an individual's intra-abdominal fat content 3
Key Considerations
When evaluating visceral adiposity using radiologic methods, it is essential to consider the following: