Magnetic resonance measurement of diffusion in the abdomen

Department of Radiology, Saint Louis University School of Medicine, St Louis, MO, USA.
Topics in magnetic resonance imaging: TMRI 04/2009; 20(2):99-104. DOI: 10.1097/RMR.0b013e3181c0d772
Source: PubMed

ABSTRACT Diffusion-weighted (DW) magnetic resonance imaging is an emerging noninvasive technique increasing its spectrum of use in the abdomen. Diffusion-weighted imaging has been used as add-on to routine abdominal protocol because it may potentially substitute contrast-enhanced imaging in cases under risk of nephrogenic systemic fibrosis. The apparent diffusion coefficient (ADC) images calculated from DW images enable qualitative and quantitative evaluations of tissue water mobility and functional environment because of changes in intracellular, extracellular, and intravascular tissue compartments. This article presents the basic physics of the ADC measurement, the techniques for performing ADC measurements of the liver and the pancreas, and the clinical applications of DW imaging.

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    ABSTRACT: At least 40% of survivors of biliary atresia have progressive cirrhosis even after undergoing Kasai operation. The values of hepatic apparent diffusion coefficient and apparent-diffusion-coefficient-related indices were applied to biliary atresia patients and correlated with cirrhotic severity scores of model for end-stage liver disease or pediatric end-stage liver disease model, Child-Turcotte, and Child-Pugh systems. Thirty-three biliary atresia patents (mean=1140, 61-4314 days of age) received magnetic resonance image examinations due to complications of biliary atresia from April 2008 to August 2009. Two non-breath-hold diffusion weighted imaging sequences were performed with motion-probing gradients in three directions with two b values: 0/100 and 0/500 s/mm2; 1000 ms/61.1 ms, time to repeat/time to echo; number of excitation, 1.0; 8 mm section thickness; 40 cm×40 cm field of view; 128×256 matrix in all biliary atresia patients and 18 control subjects. We used the Spearman rank correlation test to analyze the relationship among the scores of model for end-stage liver disease or pediatric end-stage liver disease model, Child-Turcotte and Child-Pugh scores and right hepatic apparent diffusion coefficients, apparent diffusion coefficient using b factor of 500-albumin product and alanine transaminase/apparent diffusion coefficient with b factor of 500 ratio. The right hepatic apparent diffusion coefficient using b factor of 100, apparent diffusion coefficient with b factor of 500 and product of apparent diffusion coefficient with b factor of 500-albumin level were significantly negatively correlated (p≤0.0125) with model for end-stage liver disease or pediatric end-stage liver disease model, Child-Turcotte, and Child-Pugh scores of biliary atresia patients. The ratio of alanine transaminase level/right hepatic apparent diffusion coefficient with b factor of 500 was also significantly (p≤0.0251), moderately correlated with Child-Turcotte and Child-Pugh scores (rho=0.5256 and 0.7518, respectively). Right hepatic apparent diffusion coefficient with b factor of 500 and alanine transaminase/right hepatic apparent diffusion coefficient with b factor of 500 can be useful for long-term follow-up of cirrhotic severity in biliary atresia patients.
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