Fat quantification in skeletal muscle using multigradient-echo imaging: Comparison of fat and water references

Abstract

Fat quantification in skeletal muscle using multigradient-echo imaging: Comparison of fat and water references. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal 1 Fat quantification in skeletal muscleFat quantification in skeletal muscle using multigradient-echo imaging: comparison of fat and water references 2 Fat quantification in skeletal muscle AbstractPurpose: To compare the precision, accuracy, and repeatability of water/fat imaging-based fat quantification in muscle tissue using small or large flip angles (FAs), and a water or fat reference for calculation of the proton density fat fraction (FF). Materials and methods:An Intralipid phantom and both forearms of six patients suffering from lymphedema and ten healthy volunteers were investigated in a 1.5T scanner. Two multigradient-echo sequences with eight echo times and FAs of 10° and 85° were acquired, respectively. For healthy volunteers, the acquisition of the right arm was performed twice with repositioning. From each set, water reference FF and fat reference FF images were reconstructed and the average FF and the standard deviation were calculated within the subfascial compartment. The small FA water reference was considered the reference standard.Results: The use of a fat reference effectively avoided bias due to T 1 weighting when using a large FA. The large FA fat reference approach also resulted in the highest precision, but no significant difference in repeatability between the various methods was detected. Conclusion:The precision of fat quantification in muscle tissue can be increased with maintained accuracy using a larger flip angle, if a fat reference instead of a water reference is used.

Dense breast tissue in postmenopausal women is associated with a pro-inflammatory microenvironment in vivo

“…The quantitative fat images were computed by calibrating the original fat images using adipose tissue as an internal intensity reference, thus, allowing adipose tissue volume to be quantified within segmentation. 50,51 The lean tissue volume of each breast was determined by subtracting its adipose tissue volume from its total volume. 52 Water-and fat-separated MR images were computed, as previously described, 53 from axial 3D 6-echo turbo field echo MRI images acquired on a 1.5 T Achieva (Philips Healthcare, Best, Netherlands) with a seven-element breast coil, anteriorposterior frequency encoding, first TE at 2.3 ms and DTE of 2.3 ms, TR 15.4 ms, flip angle 10 , 300 £ 300 £ 150 mm 3 field of view, 200 £ 200 scan matrix and 3 mm slice thickness.…”

Fat-Referenced MRI: Quanitaive MRI for Tissue Characterizaion and Volume Measurement

“…This aspect gives freedom when setting up the MRI protocol, and lowers the variation between systems. Throughout this work, the focus has been on T 1 -weighted images, and we primarily showed the saturation invariance in a parallel work together with Peterson et al [31]. However, the only saturation based assumption in fat-referenced MRI is that the saturation is similar in the reference and measurement location, so there is little reason to suspect that fat-referenced MRI cannot be applied to other image contrasts (such as T 2 -weighted Dixon images).…”

“…Proton density fat fraction is the fraction of MR-visible lipid protons in relation to the total number of MRvisible protons, while RFC is the amount of fat relative to that of AT. There is a strong correlation between the two techniques, which we have shown in a collaboration with Peterson et al [31]. To illustrate the similarities and differences between the two types of quanta, let PDFF be expressed in the threecompartment model:…”

“…They contribute the discrepancy to how the fat is stored tissue (as globules), which gives the fat more consistent T 1 compared to the phantom. In our collaboration with Peterson et al we showed that fat-referenced MRI was only slightly affected by the T 1 -weighting, and that the precision was higher in the T 1 -weighted state [31]. Furthermore, at ISMRM 2016 we presented a study based on 10 subjects scanned with two flip-angles (5 ○ and 10 ○ ) [90].…”

“…These calibrated images will be referred to as relative fat content (RFC) images. The calibration process limits the effect of T 1 saturation [4,31] and resolution [4,32]. This thesis aims to show that the fat-referencing technique offers good reproducibility properties by either removing or reducing many potential error sources, and that it is a good foundation for clinical body-composition applications.…”