Hepatic steatosis, the accumulation of lipids within hepatocytes, is a common condition. The prevalence of its most frequent manifestation, nonalcoholic fatty liver disease (NAFLD), has been estimated to be as high as 35% in some populations. Currently, liver biopsy is the gold standard for the diagnosis and assessment of severity of hepatic steatosis, staging of fibrosis, and is the only modality able to differentiate bland steatosis from steatohepatitis. However, its invasiveness, significant side effect profile, and susceptibility to sampling error ultimately make it a suboptimal tool. Accordingly, focus has been placed on noninvasive radiologic techniques for hepatic fat detection and quantification. The rationale, performance characteristics, and limitations of traditional noninvasive measures, including ultrasound, computed tomography, and magnetic resonance (MR) spectroscopy and imaging, are reviewed. A novel MR method, the spectrally modeled relaxation-invariant technique, overcomes the inherent weaknesses of conventional MR to diagnose and quantify hepatic steatosis over its entire range of severity. Noninvasive radiologic techniques, particularly MR, can be applied broadly, including in the diagnosis of NAFLD in asymptomatic patients with elevated serum aminotransferase levels, longitudinal monitoring of disease progression or response to treatment, population-based epidemiologic or observational studies, and drug discovery.
⁎Division of Gastroenterology and Hepatology, Department of Medicine, University of California, San Diego, San Diego, California
‡Department of Radiology, University of California, San Diego, San Diego, California
Address requests for reprints to: Claude B. Sirlin, MD, Associate Professor of Radiology In Residence, Department of Radiology, University of California, San Diego, 408 E Dickinson St, San Diego, CA 92103. fax: 619-471-0503
The authors disclose the following: Supported by National Institutes of Health grants R01 DK075128 and U01 DK061734 from the National Institute of Diabetes and Digestive and Kidney Diseases and the National Institute of Child Health and Human Development; T32 Gastroenterology Training Grant; and P60 MD00220 from the San Diego EXPORT Center, National Center of Minority Health and Health Disparities. The contents of this work are solely the responsibility of the authors and do not necessarily represent the official views of the National Institutes of Health.
Dr Sirlin has a research grant from General Electric.
ABSTRACT
Noninvasive Assessment of Hepatic Steatosis