Towards the assessment of metabolic biomarkers and creatine uptake and turnover in skeletal muscles of patients with Facioscapulohumeral muscular dystrophy using MR spectroscopy

Fascioscapulohumeral muscular dystrophy (FSHD) is a hereditary neuromuscular
condition, mainly characterised by progressive muscle weakness and atrophy of
specific skeletal muscles. In FSHD, the skeletal muscles of the face, upper arm
and shoulder region are typically affected first while involvement of other
skeletal muscles occurs later. At present it is unknown why certain skeletal
muscles are involved before others and no treatment is available for patients.
Magnetic resonance (MR) techniques can be used to obtain an image of specific
locations in the body without the need for invasive procedures or harmfull
radiation. MR imaging (MRI) is applied to obtain an anatomic image of different
tissues in the body and MR spectroscopy (MRS) can be used to visualize
concentrations of specific compounds. The advantage of MR methods is that a
subject can be measured multiple times without harm.
Studies of the skeletal muscles of other muscular dystrophies have shown a
decrease in creatine related to the severity of the disease [1]. Therefore, in
several muscular dystophies creatine supplementation is applied therapeutically
[2]. However, it is unclear whether the supplemented Cr is taken up in all
skeletal muscles at the same rate and if turnover rates differ between muscles,
while this can be important for the format of creatine supplementation.
Recently, we developed a method to non-invasively determine creatine uptake and
turnover, using 13C MRS and 13C labeled creatine, a non radioactive compound
[3].

1. Sharma U et al. 2003 Biochemical characterization of muscle tissue of limb
girdle muscular dystrophy: an 1H and 13C NMR study. NMR Biomed. Jun;
16(4):213-23)
2. Wyss, M. and A. Schulze, Health implications of creatine: can oral creatine
supplementation protect against neurological and atherosclerotic disease?
Neuroscience, 2002. 112(2): p. 243-60
3. Kan HE, van der Graaf, M, Klomp, DWJ, Vlak, M, Padberg, GW, Heerschap, A.
Intake of 13C-4 creatine enables simultaneous assessment of creatine and
phosphocreatine pools in human skeletal muscle by 13C MR spectroscopy. Magn Res
Med. 2006; 56(5): 953-957

Untill now, MRS has never been applied to skeletal muscles of FSHD patients. As
MRS provides a unique window on several compounds in skeletal muscle and some
skeletal muscles of FSH patients are affected by the disease, it is possible
that differences in metabolite concentrations are detectable by MRS.
Therefore, the goal of the present study is to determine if MR spectra of
different skeletal muscles in FSH patients show abnormalities. As different
skeletal muscles in these patients are affected more severely, MR spectra of
different skeletal muscles within one subject can be used to obtain information
on affected and not or less affected skeletal muscles. The obtained values for
FSHD patients will be compared with results from healthy volunteers.
Secondly, creatine uptake and turnover will be studied in different skeletal
muscles of healthy volunteers.

The following MR experiments will be performed at a field strenght of 3 Tesla
on FSHD patients as well as healthy volunteers. In healthy volunteers the
experiment will be performed twice on separate days to obtain a measurement for
reproducibility:

A. MR imaging to obtain an anatomic image of the lower leg (affected - not
affected muscle) and determination of the region of interest for MRS
B. 1H MRS for determination of proton detectable metabolites
C. 31P MRS for determintation of phosphorous metabolites

A second group of volunteers will be supplemented with creatine during 5 days
and MR experiments will be performed before, during and after this period. The
same protocol as described above will be applied, however, in "C" 13C MRS will
be spplied instead of 31P MRS.

- The subject is positioned on the bed in the tunnel of the MR scanner during
the MR experiment and the lower leg is positioned in a dedicated receiver. The
subject is allowed to listen to music while inside the scanner, to increase
comfort as much as possible. The MR scanner consists of a magnet with a narrow
tunnel, in which the subject is positioned with his/her leg, therefore, severe
claustrofobia is an exclusion criterium. As the tunnel is not too long, the
subjects head can remain outside of the tunnel during the experiment.
- MRS uses non-ionising radiofrequent radiation in combination with a static
magnetic field for which the FDA has formulated security guidelines. These
guidelines will be followed.
- Creatine supplementation for 5 days in a dose as applied in this study has
been shown to not have any adverse effects on health [2].