Fat Quantification (fat + quantification)

Distribution by Scientific Domains


Selected Abstracts


Pancreatic enzyme replacement therapy: exocrine pancreatic insufficiency after gastrointestinal surgery

HPB, Issue 2009
J. Enrique Domínguez-Muñoz
Abstract Exocrine pancreatic insufficiency (EPI) and resultant maldigestion occurs in up to 80% of patients following gastric, duodenal or pancreatic surgery. Accurate diagnosis is required to determine the appropriate intervention, but the conventional method of faecal fat quantification is time-consuming and not always readily available. The optimized 13C-mixed triglyceride (13C-MTG) breath test is an accurate alternative post-surgery. Pancreatic enzyme replacement therapy (PERT) is indicated post-surgery in patients with clinically evident steatorrhoea, weight loss or maldigestion-related symptoms. Given its favourable safety profile, PERT is also appropriate in asymptomatic patients with high faecal fat excretion as such patients are at high risk for nutritional deficits. However, published data evaluating PERT in this setting are limited. Uncoated powder preparations may be preferred in cases of low gastric acidity and partial or total gastric resection. In clinical studies, enteric-coated microspheres were associated with greater weight gain after surgery vs. uncoated preparations. This was confirmed in a recent study using the 13C-MTG breath test; fat absorption increased from <40% without therapy to almost 60% with enteric-coated minimicrospheres (40 000 lipase units/meal), with >60% of patients achieving normal breath test results (i.e. normal fat digestion) during PERT. A therapeutic algorithm for the treatment of EPI after surgery is also discussed. [source]


Quantification of hepatic steatosis with MRI: The effects of accurate fat spectral modeling

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2009
Scott B. Reeder MD
Abstract Purpose To develop a chemical-shift,based imaging method for fat quantification that accounts for the complex spectrum of fat, and to compare this method with MR spectroscopy (MRS). Quantitative noninvasive biomarkers of hepatic steatosis are urgently needed for the diagnosis and management of nonalcoholic fatty liver disease (NAFLD). Materials and Methods Hepatic steatosis was measured with "fat-fraction" images in 31 patients using a multiecho chemical-shift,based water-fat separation method at 1.5T. Fat-fraction images were reconstructed using a conventional signal model that considers fat as a single peak at ,210 Hz relative to water ("single peak" reconstruction). Fat-fraction images were also reconstructed from the same source images using two methods that account for the complex spectrum of fat; precalibrated and self-calibrated "multipeak" reconstruction. Single-voxel MRS that was coregistered with imaging was performed for comparison. Results Imaging and MRS demonstrated excellent correlation with single peak reconstruction (r2 = 0.91), precalibrated multipeak reconstruction (r2 = 0.94), and self-calibrated multipeak reconstruction (r2 = 0.91). However, precalibrated multipeak reconstruction demonstrated the best agreement with MRS, with a slope statistically equivalent to 1 (0.96 ± 0.04; P = 0.4), compared to self-calibrated multipeak reconstruction (0.83 ± 0.05, P = 0.001) and single-peak reconstruction (0.67 ± 0.04, P < 0.001). Conclusion Accurate spectral modeling is necessary for accurate quantification of hepatic steatosis with MRI. J. Magn. Reson. Imaging 2009;29:1332,1339. © 2009 Wiley-Liss, Inc. [source]


Independent estimation of T*2 for water and fat for improved accuracy of fat quantification

MAGNETIC RESONANCE IN MEDICINE, Issue 4 2010
Venkata V. Chebrolu
Abstract Noninvasive biomarkers of intracellular accumulation of fat within the liver (hepatic steatosis) are urgently needed for detection and quantitative grading of nonalcoholic fatty liver disease, the most common cause of chronic liver disease in the United States. Accurate quantification of fat with MRI is challenging due the presence of several confounding factors, including T*2 decay. The specific purpose of this work is to quantify the impact of T*2 decay and develop a multiexponential T*2 correction method for improved accuracy of fat quantification, relaxing assumptions made by previous T*2 correction methods. A modified Gauss-Newton algorithm is used to estimate the T*2 for water and fat independently. Improved quantification of fat is demonstrated, with independent estimation of T*2 for water and fat using phantom experiments. The tradeoffs in algorithm stability and accuracy between multiexponential and single exponential techniques are discussed. Magn Reson Med 63:849,857, 2010. © 2010 Wiley-Liss, Inc. [source]