Liver fat is reproducibly measured using computed tomography in the Framingham Heart Study

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Abstract
Background and Aims: Fatty liver is the hepatic manifestation of obesity, but community-based assessment of fatty liver among unselected patients is limited. We sought to determine the feasibility of and optimal protocol for quantifying fat content in the liver in the Framingham Heart Study using multidetector computed tomography (MDCT) scanning. Methods: Participants (n = 100, 49% women, mean age 59.4 years, mean body mass index 27.8 kg/m2) were drawn from the Framingham Heart Study cohort. Two readers measured the attenuation of the liver, spleen, paraspinal muscles, and an external standard from MDCT scans using multiple slices in chest and abdominal scans. Results: The mean measurement variation was larger within a single axial computed tomography (CT) slice than between multiple axial CT slices for the liver and spleen, whereas it was similar for the paraspinal muscles. Measurement variation in the liver, spleen, and paraspinal muscles was smaller in the abdomen than in the chest. Three versus six measures of attenuation in the liver and two versus three measures in the spleen gave reproducible measurements of tissue attenuation (intraclass correlation coefficient [ICCC] of 1 in the abdomen). Intrareader and interreader reproducibility (ICCC) of the liver-to-spleen ratio was 0.98 and 0.99, the liver-to-phantom ratio was 0.99 and 0.99, and the liver-to-muscle ratio was 0.93 and 0.86, respectively. Conclusion: One cross-sectional slice is adequate to capture the majority of variance of fat content in the liver per individual. Abdominal scan measures as compared to chest scan measures of fat content in the liver are more precise. The measurement of fat content in the liver on MDCT scans is feasible and reproducible.