The Concept of CMR
Slides, videos and moreThe Concept of CMR
Intra-abdominal Adipose Tissue: the Culprit?
Liver Fat
- 1Key Points (1 page)
- 2Liver Fat: a Marker of Ectopic Fat Deposition (1 page)
- 3Epidemiology (1 page)
- 4Liver Fat and Metabolic Disease (1 page)
- 5Pathogenesis (3 pages)
- 6Measuring Liver Fat (2 pages)
- 7References (1 page)
Measuring Liver Fat
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Figure 2: 
Figure 2: Liver biopsy is generally considered the gold standard for assessing hepatic steatosis (17). However, a liver biopsy sample is a mere 1/50,000 of total organ mass (61), and because liver tissue is so heterogeneous, this small sample is likely to be a biased estimate of overall hepatic steatosis. Studies using multiple biopsy samples have shown considerable sampling variability for various hepatic histological features, including the diagnosis and staging of non-alcoholic fatty liver disease (62). A biopsy procedure can also cause post-procedure pain, hypotension, intraperitoneal hemorrhage, bacterial infection, and a small but definite risk of mortality (63).
Advanced imaging techniques such as computed tomography (CT) and proton-magnetic resonance spectroscopy (H1-MRS) have emerged as safe, reliable, and non-invasive alternatives to liver biopsy. Liver attenuation on a CT image depends on liver density, which depends on the degree of fat infiltration: the higher the fat content, the lower the attenuation value, and the darker the CT image of the liver (Figure 2). Strong correlations have been observed between CT and histological measures of liver fat (r=-0.77) (64). H1–MRS, an alternate imaging technique that does not use x-ray energy, also correlates well with biopsy assessments of liver fat (64-66). Though H1–MRS produces a quantitative measure of liver fat and CT a qualitative analysis (67), these measures correlate well with each other (r>0.80) (64, 65). Unfortunately, these imaging techniques only detect liver fat when over 30% of the liver tissue is already infiltrated with fat (68). In addition, no imaging technique is capable of differentiating between degrees of non-alcoholic liver disease, particularly between hepatic steatosis and steatohepatitis (68), a clinically relevant distinction.
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