Quantitative Assessment of Muscle Fat in Sarcopenia Using Magnetic Resonance Imaging (MRI) and Spectroscopy (MRS)
Alexandra Grimm1,2, Heiko Meyer2, Mathias Nittka2, Esther Raithel2, Andreas Friedberger1, Marc Teschler1, Michael Uder3, Wolfgang Kemmler1, Klaus Engelke1, and Harald H. Quick1,4

1Institute of Medical Physics, Erlangen, Germany, 2Product Definition & Innovation, Siemens Healthcare GmbH, Erlangen, Germany, 3Institute of Radiology, University Hospital Erlangen, Erlangen, Germany, 4Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany


Sarcopenia describes muscle degeneration. In particular with increasing age, muscle tissue is replaced by fatty infiltrations. We developed an MRI sequence protocol (T1w TSE, PDw SPACE, PDw TSE Dixon, q-Dixon, and HISTO) for quantifying this degradation and applied it twice to 54 patients suffering from sarcopenia. Between both measurements three months of whole body electromyostimulation (EMS) training were performed. Initial results show that image data can be used for muscle segmentation and determination of muscle volumes, fat fractions, and fat distribution within the muscles. Muscle fat fractions correlate with muscle strength. In spectroscopy accurate voxel repositioning is challenging.


Sarcopenia is a syndrome characterized by loss of skeletal muscle mass and function, mainly caused by replacement of muscle tissue with intramuscular fat, which restricts muscle function1. The purpose of this study was to develop an MRI pulse sequence protocol suitable for quantifying muscle volume, intramuscular fat, and its distribution within the muscle.


54 females (> 70 yrs) with sarcopenia, randomized in control (n1 = 19) and training (n2 = 35) groups, were examined twice using a 3T system (MAGNETOM Skyrafit, Siemens, Erlangen, Germany). Between both measurements, whole body electromyostimulation (miha bodytec, Gersthofen, Germany) training (20 minutes, 85 Hz, 350 ms, 6 s EMS - 4 s rest, once weekly) was carried out over a period of three months.

MRI acquisition was performed at the thigh (18-channel BodyFlex surface coil) and included the following sequences: T1w TSE, PDw SPACE, PDw TSE Dixon, q-Dixon (multi-echo GRE VIBE Dixon), and HISTO (multi-echo T2-corrected single voxel spectroscopy, at musculus semitendinosus). The total acquisition time (incl. localizer) was 16:17 min. Detailed sequence parameters are given in Figure 1.

Multiple contrasts were acquired using the q-Dixon sequence to quantify fat accurately2,3. T1 bias was addressed by using a low flip angle of 4 degree and T2* decay considered as a degree of freedom in the parameter extraction4,5. Fat and water fractions were calculated as parametric maps.

Spectroscopic fat quantification with T2-correction was done by extrapolating fat and water integrals for TE = 0 using an exponential fit of signal peaks acquired at five successive TEs6. The long TR of 3000 ms was chosen to avoid T1 bias4,7.

In addition, isokinetic maximum leg extension and flexion strength (0.6 m/s) were measured for all patients using a leg press (Con-Trex LP physiomed, Schnaittach, Germany) at baseline and follow-up exams.


All 54 patients were examined successfully twice. Figures 2 and 3 show results of one randomly chosen training group patient for T1w TSE and PDw SPACE sequences and PDw TSE Dixon and q-Dixon sequences, respectively. Figure 4 shows a q-Dixon fat fraction image for three-month follow-up exam after manual muscle segmentation in comparison with an anatomical thigh muscle model8. Fat fractions were calculated for each muscle.

MRS (Figure 5) showed a change of fat content in m. semitendinosus over all controls of +2.86% ± 15.59% (MV ± SD) and of +9.53% ± 16.92% in the training group.

For the patient exemplarily shown in Figures 2-5 maximum leg extension strengths were 1088 N and 1180 N and flexion strength 366 and 266 N at baseline and follow-up exams, respectively. For all patients average extension strength was 1261 N ± 393 N (MV ± SD) and flexion strength 479 N ± 203 N.


The sequences and derived MR images are suited to analyze and quantify different parameters. T1w TSE and PDw SPACE images show high spatial and contrast resolution beneficial for morphological analysis. PDw SPACE images have the additional advantage of a smaller slice thickness.

Muscle-fat-boundaries always appear hypointense on opposed-phase Dixon images (Figures 3c/f), as in these areas fat and water concentrations are similar. Hence, they can be used for segmentation of individual muscles2. Q-Dixon’s fat and water fraction images give additional quantitative information on tissue composition.

Muscles stressed through extension are vastus lateralis, rectus femoris, vastus intermedius, and vastus medialis (quadriceps femoris) while the largest part of flexion (37%) is carried by semimembranosus9. The high fat content (25.86%) in the semimembranosus of the shown patient (Figure 4) may explain the low flexion strength compared to the group average. However, this finding has to be proven for the whole patient collective before a definitive conclusion can be derived. Priorly, a robust and automated segmentation algorithm has to be developed.

Spectroscopy is considered as reference standard for fat quantification in e.g. liver MRI10. Though, since muscle is flexibly formable, voxel repositioning in longitudinal studies is limited due to inhomogeneous fat/muscle distribution within large spectroscopic voxel volumes. While a comparable follow-up voxel position could be selected in the patient shown in Figures 5a/b, this was not feasible in Figures 5c/d. This challenge is also reflected in the high SD of the change in fat content. Unlike spectroscopy, imaging sequences are easier to perform and reproduce and changes in muscle parameters are representative for the whole muscle rather than for a single voxel.


Current results of our examination show that MRI is capable to measure parameters quantifying muscle degradation in sarcopenic disease, while the use of spectroscopy involves challenges with regard to voxel repositioning and assessment of the entire muscle volume.


The study is supported by the Bavarian Research Foundation (FORMOsA AZ-1044-12).


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Figure 1: Detailed sequence parameter of the sarcopenic MR imaging and spectroscopy protocol.

Figure 2: T1w TSE (a and b) and PDw SPACE (c and d). Baseline (left) and follow-up (right) exams of one patient (74 yrs) performing EMS training over a period of three months. Both sequences show excellent delineation of fat and muscle with high spatial resolution.

Figure 3: PDw TSE Dixon (a - c) and q-Dixon (d - f) of one patient at three-month follow-up exam. Water (a and d), fat (b and e), and opposed-phase (c and f) images.

Figure 4: Anatomical thigh muscle model at mid femur (a)10 and q-Dixon fat fraction image for follow-up exam after manual segmentation with the results of fat fraction calculation for each muscle; exemplarily shown for one patient (74 yrs) (b).

Figure 5: Yellow mark: Area examined using HISTO at semitendinosus for the patient also shown in Figs. 2-4 (a, b) and another patient (c, d) at baseline (a, c) and follow-up (b, d) exam. Fat content results a: 8.65%; b: 8.33%; c: 27.56%; d: 33.57% in these two examples.

Proc. Intl. Soc. Mag. Reson. Med. 24 (2016)