Liver fat quantification using a multi‐step adaptive fitting approach with multi‐echo GRE imaging. Issue 5 (9th December 2013)

• Record Type: Journal Article
• Authors: Zhong, Xiaodong; Nickel, Marcel D.; Kannengiesser, Stephan A.R.; Dale, Brian M.; Kiefer, Berthold; Bashir, Mustafa R.
• Is Part Of: Magnetic resonance in medicine. Volume 72:Issue 5(2014:Nov.)
• Page Start: 1353
• Page End: 1365
• Publication Date: 2013-12-09
• Subjects: Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.25054
• Languages: English
• ISSNs: 0740-3194

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="mrm25054-sec-0001" sec-type="section"> <title>Purpose</title> <p>The purpose of this study was to develop a multi‐step adaptive fitting approach for liver proton density fat fraction (PDFF) and <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh2ckh5rvh" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:07403194:media:mrm25054:mrm25054-math-0001" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>R</mml:mi><mml:mn>2</mml:mn><mml:mo>*</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> quantification, and to perform an initial validation on a broadly available hardware platform.</p> </sec> <sec id="mrm25054-sec-0002" sec-type="section"> <title>Theory and Methods</title> <p>The proposed method uses a multi‐echo three‐dimensional gradient echo acquisition, with initial guesses for the fat and water signal fractions based on a Dixon decomposition of two selected echoes. Based on magnitude signal equations with a multi‐peak fat spectral model, a multi‐step nonlinear fitting procedure is then performed to adaptively update the fat and water signal fractions and <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh2ckh5rsd" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:07403194:media:mrm25054:mrm25054-math-0002" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mi>R</mml:mi><mml:mn>2</mml:mn><mml:mo>*</mml:mo></mml:msubsup></mml:mrow></mml:math></alternatives></inline-formula> values. The proposed method was validated using numeric phantoms as ground truth, followed by preliminary clinical validation of PDFF calculations against spectroscopy in 30 patients.</p> </sec> <sec id="mrm25054-sec-0003" sec-type="section"> <title>Results</title> <p>The results of the proposed method agreed well with the ground truth of numerical phantoms, and were relatively insensitive to changes in field strength, field homogeneity, monopolar/bipolar readout, signal to noise ratio, and echo time selections. The in vivo patient study showed excellent consistency between the PDFF values measured with the proposed approach compared with spectroscopy.</p> </sec> <sec id="mrm25054-sec-0004" sec-type="section"> <title>Conclusion</title> <p>This multi‐step adaptive fitting approach performed well in both simulated and initial clinical evaluation, and shows potential in the quantification of hepatic steatosis. Magn Reson Med 72:1353–1365, 2014. © 2013 Wiley Periodicals, Inc.</p> </sec> </abstract>