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Differentiating supraclavicular from gluteal adipose tissue based on simultaneous PDFF and T 2 * mapping using a 20‐echo gradient‐echo acquisition
Author(s) -
Franz Daniela,
Diefenbach Maximilian N.,
Treibel Franziska,
Weidlich Dominik,
Syväri Jan,
Ruschke Stefan,
Wu Mingming,
Holzapfel Christina,
Drabsch Theresa,
Baum Thomas,
Eggers Holger,
Rummeny Ernst J.,
Hauner Hans,
Karampinos Dimitrios C.
Publication year - 2019
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.26661
Subject(s) - gradient echo , nuclear medicine , echo (communications protocol) , magnetic resonance imaging , adipose tissue , medicine , nuclear magnetic resonance , anatomy , radiology , physics , computer science , computer network
Background Adipose tissue (AT) can be classified into white and brown/beige subtypes. Chemical shift encoding‐based water–fat MRI‐techniques allowing simultaneous mapping of proton density fat fraction (PDFF) and T 2 * result in a lower PDFF and a shorter T 2 * in brown compared with white AT. However, AT T 2 * values vary widely in the literature and are primarily based on 6‐echo data. Increasing the number of echoes in a multiecho gradient‐echo acquisition is expected to increase the precision of AT T 2 * mapping. Purpose 1) To mitigate issues of current T 2 *‐measurement techniques through experimental design, and 2) to investigate gluteal and supraclavicular AT T 2 * and PDFF and their relationship using a 20‐echo gradient‐echo acquisition. Study Type Prospective. Subjects Twenty‐one healthy subjects. Field Strength/Sequence Assessment First, a ground truth signal evolution was simulated from a single‐T 2 * water–fat model. Second, a time‐interleaved 20‐echo gradient‐echo sequence with monopolar gradients of neck and abdomen/pelvis at 3 T was performed in vivo to determine supraclavicular and gluteal PDFF and T 2 *. Complex‐based water–fat separation was performed for the first 6 echoes and the full 20 echoes. AT depots were segmented. Statistical Tests Mann‐Whitney test, Wilcoxon signed‐rank test and simple linear regression analysis. Results Both PDFF and T 2 * differed significantly between supraclavicular and gluteal AT with 6 and 20 echoes (PDFF: P < 0.0001 each, T 2 *: P = 0.03 / P < 0.0001 for 6/20 echoes). 6‐echo T 2 * demonstrated higher standard deviations and broader ranges than 20‐echo T 2 *. Regression analyses revealed a strong relationship between PDFF and T 2 * values per AT compartment (R 2 = 0.63 supraclavicular, R 2 = 0.86 gluteal, P < 0.0001 each). Data Conclusion The present findings suggest that an increase in the number of sampled echoes beyond 6 does not affect AT PDFF quantification, whereas AT T 2 * is considerably affected. Thus, a 20‐echo gradient‐echo acquisition enables a multiparametric analysis of both AT PDFF and T 2 * and may therefore improve MR‐based differentiation between white and brown fat. Level of Evidence : 2 Technical Efficacy : Stage 2 J. Magn. Reson. Imaging 2019;50:424–434.