Spatial distribution of MRI-determined hepatic proton density fat fraction in adults with nonalcoholic fatty liver disease

Abstract

Purpose To describe the spatial distribution of liver fat, using magnetic resonance imaging (MRI)-estimated proton density fat fraction (PDFF), in adults with non-alcoholic fatty liver disease (NAFLD). Materials and Methods This IRB-approved, HIPAA-compliant study prospectively enrolled fifty adults (30 women, 20 men) with biopsy-proven NAFLD. Hepatic PDFF was measured by low-flip-angle multiecho spoiled gradient-recalled-echo MRI at 3T. Three non-overlapping regions of interest were placed within each liver segment. Statistical analyses included Pearson’s correlation, multivariable linear regression, and permutation-based paired tests. Results The study population’s mean whole-liver PDFF was 16.1% (range: 1.6–39.6%). The mean whole-liver PDFF variability was 1.9% (range: 0.7–4.5%). Higher variability was associated with higher PDFF (r=0.34, p=0.0156). The mean PDFF was significantly higher in the right lobe than the left (16.5% vs. 15.3%, p=0.0028). The mean PDFF variability was higher in the left lobe than the right (1.86% vs. 1.28%, p<0.0001). Segment II had the lowest mean segmental PDFF (14.8%); segment VIII had the highest (16.7%). Segments V (0.71%) and VI (0.70%) had the lowest mean segmental PDFF variability; segment II had the highest (1.32%). Conclusion In adult NAFLD there are small but significant differences in fat content and variability between lobes and some of the segments.

MRI and MRE for non-invasive quantitative assessment of hepatic steatosis and fibrosis in NAFLD and NASH: Clinical trials to clinical practice

“…Thus, similar to liver biopsies, MRS evaluates a small portion of the liver to quantify steatosis (although the ~ 8cm 3 MRS voxel is orders of magnitude than a typical core biopsy) and does not depict the distribution of steatosis throughout the liver parencyhma. 17 Second, the complexity of MRS requires significant expertise for its acquisition and analysis, and it is not readily available on all scanners, which limits its routine application in clinical trials and clinical practice. Finally, although MRS is considered to be potentially more accurate, the diagnostic accuracy, reliability, and responsiveness of MRI-PDFF assessments have consistently been demonstrated to be highly correlated with MRS-based PDFF assessments across multiple studies.…”

“…13–16 Furthermore, although fat accumulation within the liver tends to be diffuse, the distribution is often non-uniform which results in inaccurate assessments of disease progression or regression due to spatial variability in sampling. 17–22 These limitations carry significant implications for clinical trials as the diagnostic accuracy, reliability, and responsiveness of treatment end-points impact trial size requirements, feasibility, and costs. Furthermore, translating these findings to routine practice is difficult given the inability to perform routine frequent liver biopsies in clinical practice.…”

Magnetic Resonance Elastography vs Transient Elastography in Detection of Fibrosis and Noninvasive Measurement of Steatosis in Patients With Biopsy-Proven Nonalcoholic Fatty Liver Disease

“…6-8 Although liver biopsy is the current gold standard for assessing NAFLD, its accuracy has been questioned because of sampling errors and variable intra- and inter-observer agreement. 9-11 Moreover, biopsy is invasive, which limits use as a population screening tool. Thus, there is a need for accurate, noninvasive methods that can clinically assess NAFLD.…”

Magnetic Resonance Elastography vs Transient Elastography in Detection of Fibrosis and Noninvasive Measurement of Steatosis in Patients with Biopsy-Proven Nonalcoholic Fatty Liver Disease

“…34,45,46 Our study shows that MRI-based techniques are superior to TE for detecting any fibrosis and steatosis in NAFLD patients who may be at increased risk for mortality and other poor prognostic outcomes. Other advantages of MRI-based techniques over TE include larger area of the liver measured, which may reduce sampling variability secondary to heterogeneity of fibrosis, 9,11 and the utility of MRI-PDFF for assessing longitudinal changes in steatosis. 47 Although TE has excellent inter-and intra-operator reproducibility 48 and is accurate for diagnosing cirrhosis, 12 its applicability is limited by high failure rates in patients with narrow intercostal space and ascites, 12 interference of liver stiffness measurements by extrahepatic cholestasis and acute liver injury, 49,50 and reduced reproducibility in early stages of fibrosis and in the presence of steatosis.…”

“…[6][7][8] Although liver biopsy is the current gold standard for assessing NAFLD, its accuracy has been questioned because of sampling errors and variable intra-and inter-observer agreement. [9][10][11] Moreover, biopsy is invasive, which limits use as a population screening tool. Thus, there is a need for accurate, noninvasive methods that can clinically assess NAFLD.…”