Effect of flip angle on the accuracy and repeatability of hepatic proton density fat fraction estimation by complex data‐based, T1‐independent, T2*‐corrected, spectrum‐modeled MRI. Issue 2 (17th April 2013)

• Record Type: Journal Article
• Authors: Johnson, Benjamin L.; Schroeder, Michael E.; Wolfson, Tanya; Gamst, Anthony C.; Hamilton, Gavin; Shiehmorteza, Masoud; Loomba, Rohit; Schwimmer, Jeffrey B.; Reeder, Scott; Middleton, Michael S.; Sirlin, Claude B.
• Is Part Of: Journal of magnetic resonance imaging. Volume 39:Issue 2(2014)
• Page Start: 440
• Page End: 447
• Publication Date: 2013-04-17
• Subjects: Magnetic resonance imaging -- Periodicals; 616
• DOI: 10.1002/jmri.24153
• Languages: English
• ISSNs: 1053-1807

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="jmri24153-sec-0001" sec-type="section"> <title>Purpose</title> <p>To evaluate the effect of flip angle (FA) on accuracy and within‐examination repeatability of hepatic proton‐density fat fraction (PDFF) estimation with complex data‐based magnetic resonance imaging (MRI).</p> </sec> <sec id="jmri24153-sec-0002" sec-type="section"> <title>Materials and Methods</title> <p>PDFF was estimated at 3T in 30 subjects using two sets of five MRI sequences with FA from 1° to 5° in each set. One set used 7 msec repetition time and acquired 6 echoes (TR7/E6); the other used 14 msec and acquired 12 echoes (TR14/E12). For each FA in both sets the accuracy of MRI‐PDFF was assessed relative to MR spectroscopy (MRS)‐PDFF using four regression parameters (slope, intercept, average bias, R<sup>2</sup>). Each subject had four random sequences repeated; within‐examination repeatability of MRI‐PDFF for each FA was assessed with intraclass correlation coefficient (ICC). Pairwise comparisons were made using bootstrap‐based tests.</p> </sec> <sec id="jmri24153-sec-0003" sec-type="section"> <title>Results</title> <p>Most FAs provided high MRI‐PDFF estimation accuracy (intercept range −1.25 to 0.84, slope 0.89–1.06, average bias 0.24–1.65, R<sup>2</sup> 0.85–0.97). Most comparisons of regression parameters between FAs were not significant. Informally, in the TR7/E6 set, FAs of 2° and 3° provided the highest accuracy, while FAs of 1° and 5° provided the lowest. In the TR14/E12 set, accuracy parameters did not differ consistently between FAs. FAs in both sets provided high within‐examination repeatability (ICC range 0.981–0.998).</p> </sec> <sec id="jmri24153-sec-0004" sec-type="section"> <title>Conclusion</title> <p>MRI‐PDFF was repeatable and, for most FAs, accurate in both sequence sets. In the TR7/E6 sequence set, FAs of 2° and 3° informally provided the highest accuracy. In the TR14/E12 sequence set, all FAs provided similar accuracy. <bold>J. Magn. Reson. Imaging 2014;39:440–447</bold>. © <bold>2013 Wiley Periodicals, Inc</bold>.</p> </sec> </abstract>