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Journal ArticleDOI

Nonalcoholic Fatty Liver Disease: MR Imaging of Liver Proton Density Fat Fraction to Assess Hepatic Steatosis

01 May 2013-Radiology (Radiological Society of North America, Inc.)-Vol. 267, Iss: 2, pp 422-431
TL;DR: MR imaging-PDFF showed promise for assessment of hepatic steatosis grade in patients with NAFLD, and was significantly correlated with histologic steatotic grade.
Abstract: MR imaging with proton density fat fraction (PDFF) permitted high overall accuracy with moderate sensitivity and high specificity for classification of dichotomized steatosis grade, and these results support the conduct of further studies to help validate MR imaging–PDFF as a biomarker of hepatic steatosis in nonalcoholic fatty liver disease.
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Journal ArticleDOI
17 Dec 2015
TL;DR: No effective medical interventions exist that completely reverse the disease other than lifestyle changes, dietary alterations and, possibly, bariatric surgery, however, several strategies that target pathophysiological processes such as an oversupply of fatty acids to the liver, cell injury and inflammation are currently under investigation.
Abstract: Nonalcoholic fatty liver disease (NAFLD) is a disorder characterized by excess accumulation of fat in hepatocytes (nonalcoholic fatty liver (NAFL)); in up to 40% of individuals, there are additional findings of portal and lobular inflammation and hepatocyte injury (which characterize nonalcoholic steatohepatitis (NASH)). A subset of patients will develop progressive fibrosis, which can progress to cirrhosis. Hepatocellular carcinoma and cardiovascular complications are life-threatening co-morbidities of both NAFL and NASH. NAFLD is closely associated with insulin resistance; obesity and metabolic syndrome are common underlying factors. As a consequence, the prevalence of NAFLD is estimated to be 10-40% in adults worldwide, and it is the most common liver disease in children and adolescents in developed countries. Mechanistic insights into fat accumulation, subsequent hepatocyte injury, the role of the immune system and fibrosis as well as the role of the gut microbiota are unfolding. Furthermore, genetic and epigenetic factors might explain the considerable interindividual variation in disease phenotype, severity and progression. To date, no effective medical interventions exist that completely reverse the disease other than lifestyle changes, dietary alterations and, possibly, bariatric surgery. However, several strategies that target pathophysiological processes such as an oversupply of fatty acids to the liver, cell injury and inflammation are currently under investigation. Diagnosis of NAFLD can be established by imaging, but detection of the lesions of NASH still depend on the gold-standard but invasive liver biopsy. Several non-invasive strategies are being evaluated to replace or complement biopsies, especially for follow-up monitoring.

546 citations

Journal ArticleDOI
TL;DR: In a prospective, cross-sectional study of more than 100 patients, MRE is found to be more accurate than TE in identification of liver fibrosis (stage 1 or more), using biopsy analysis as the standard and MRI-PDFF is more accurate in detecting all grades of steatosis in patients with NAFLD.

441 citations


Cites methods from "Nonalcoholic Fatty Liver Disease: M..."

  • ...sequences were acquired according to methods published previously.(28,29,39) Median time interval between MRI and biopsy was 42 days....

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Journal ArticleDOI
TL;DR: MRE is accurate in predictingAdvanced fibrosis and may be utilized for noninvasive diagnosis of advanced fibrosis in patients with NAFLD.

380 citations


Cites methods from "Nonalcoholic Fatty Liver Disease: M..."

  • ...A trained image analyst (6 months of experience with MRE) in the MR3T research laboratory manually placed 2-cm-diameter circular ROIs in each of the nine hepatic segments on the maps, avoiding large blood vessels, liver edges, and (if any) artifacts.(39,51) The mean liver PDFF was calculated by averaging the per-pixel PDFF values across the ROIs in each segment, and the results were outputted automatically to an electronic spreadsheet....

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Journal ArticleDOI
TL;DR: Current imaging methods used to evaluate hepatic steatosis, including the diagnostic accuracy, limitations, and practical applicability of each method are reviewed, and the potential role of elastography techniques in the evaluation of patients with NAFLD is described.
Abstract: Nonalcoholic fatty liver disease (NAFLD) is a frequent cause of chronic liver diseases, ranging from simple steatosis to nonalcoholic steatohepatitis (NASH)-related liver cirrhosis. Although liver biopsy is still the gold standard for the diagnosis of NAFLD, especially for the diagnosis of NASH, imaging methods have been increasingly accepted as noninvasive alternatives to liver biopsy. Ultrasonography is a well-established and cost-effective imaging technique for the diagnosis of hepatic steatosis, especially for screening a large population at risk of NAFLD. Ultrasonography has a reasonable accuracy in detecting moderate-to-severe hepatic steatosis although it is less accurate for detecting mild hepatic steatosis, operator-dependent, and rather qualitative. Computed tomography is not appropriate for general population assessment of hepatic steatosis given its inaccuracy in detecting mild hepatic steatosis and potential radiation hazard. However, computed tomography may be effective in specific clinical situations, such as evaluation of donor candidates for hepatic transplantation. Magnetic resonance spectroscopy and magnetic resonance imaging are now regarded as the most accurate practical methods of measuring liver fat in clinical practice, especially for longitudinal follow-up of patients with NAFLD. Ultrasound elastography and magnetic resonance elastography are increasingly used to evaluate the degree of liver fibrosis in patients with NAFLD and to differentiate NASH from simple steatosis. This article will review current imaging methods used to evaluate hepatic steatosis, including the diagnostic accuracy, limitations, and practical applicability of each method. It will also briefly describe the potential role of elastography techniques in the evaluation of patients with NAFLD.

320 citations

Journal ArticleDOI
TL;DR: This trial demonstrates the application of colocalization of MRI‐PDFF‐derived fat maps and magnetic resonance elastography‐derived stiffness maps of the liver before and after treatment to noninvasively assess treatment response in NASH.

278 citations


Additional excerpts

  • ...which the fat content is calculated(1)....

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References
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Journal ArticleDOI
TL;DR: There are no systems for grading necroinflammatory activity or for staging fibrosis as exist for various other forms of chronic liver disease and this study proposes a grading and staging system that reflects the unique histological features of nonalcoholic steatohepatitis.

3,553 citations

Journal ArticleDOI
TL;DR: It is suggested that a length of at least 25 mm is necessary to evaluate fibrosis accurately with a semiquantitative score, because variability in the distribution of fibrosis within the liver is a major limitation when using more accurate methods such as automated image analysis.

2,207 citations

Journal ArticleDOI
TL;DR: Sampling error and intraobserver variation in liver biopsy in patients with chronic HCV infection is found to be low and consistent with previous studies.

1,839 citations

Journal ArticleDOI
TL;DR: Histologic lesions of NASH are unevenly distributed throughout the liver parenchyma; therefore, sampling error of liver biopsy can result in substantial misdiagnosis and staging inaccuracies.

1,764 citations