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to applicability for longitudinal studies of the pattern and
involvement of fat infiltration in OPMD patients.
Methods: Imaging on 8 OPMD patients 5 healthy volunteers
was performed on a 1.5 T MR scanner. Two axial slice groups
were chosen at predefined distances from the knee joint, one
in the thigh and one in the calf. The protocol consisted of a T1-
weighted turbo spin echo sequence for anatomical reference
(fig. 1), two gradient echo sequences for 2-point Dixon
imaging [2], a multi-contrast TSE sequence for quantification
of transverse relaxation times T2, and a steady-state free
precession (SSFP) sequence for histogram analyses (total
acquisition time 20:44 min). Regions of interest (ROI) were
drawn in 11 thigh and 10 calf muscles (fig. 1).
Results: Mean fat infiltration in the whole thigh and calf (fig. 2a)
of all patients significantly differed from values of the healthy
controls according to all methods except for the thigh muscles
of patient 7. All techniques suggest that patients 2 and 4 are
most affected by fat infiltration. Figure 2b exemplary illustrates
the quantification of fat infiltration in the individual thigh muscles
based on T2 values. The T2 values enabled a differentiation
between patients and controls in 74%, the 2-point Dixon method
in 58% and the SSFP method in 52% of the 168 examined
patient muscles. Furthermore, a strong linear correlation is
observed between the three quantitative methods
(0.78 < R 2 < 0.94).
Conclusions: This work demonstrates that non-invasive
quantification of fat infiltration in OPMD patients can be
performed with different MR imaging methods. The mean fat
fractions across all muscles can provide an impression of muscle
degeneration. A detailed pattern of individual muscle involvement
may help on the understanding of the disease and serve as a
baseline for longitudinal studies. For an optimal assessment
of therapy effectiveness, objective measures of muscle tissue
integrity, such as multiecho Dixon techniques and quantitative
T2 determination, are indispensable.
References: 1 Brais B, et al. Nat Genet. 1998;18:164–7. 2 Dixon
WT. Radiology. 1984;153(1):189–94.
Figure 2
(a) Mean fat fractions (primary y-axis) using the 2-point Dixon
(2PD) method and SSFP histogram analysis, and mean T2
values (secondary y-axis) across left/right side and all muscles
(first y-axis). Mean value and 2SD of 5 healthy controls and
results of the individual OPMD patients are displayed.
(b) Quantification of fat infiltration in the individual thigh and calf
muscles based on T2 values. Mean value (± 2 SD) across all
healthy volunteers are shown for each muscle and opposed to
values in individual muscles of OPMD patients (P1-P8). Muscles
are sorted according to the mean values across all subjects in
descending order.
a
b
Figure 1
Exemplary T1-weighted images of thigh and calf muscles of
an OPMD patient. (a) Abbreviations of thigh muscles: adductor
longus (AL), adductor magnus (AM), biceps femoris caput
breve (BB), biceps femoris caput longum (BL), gracilis (GR),
rectus femoris (RF), sartorius (SA), semimembranosus (SM),
semitendinosus (ST), vastus intermedius (VI), vastus lateralis
(VL), vastus medialis (VM). (b) Abbreviations calf muscles:
extensores longi digitorum et hallucis (ED), fibularis brevis (FB),
flexor digitorum longus (FD), flexor hallucis longus (FH), fibularis
longus (FL), gastrocnemius caput laterale (GL), gastrocnemius
caput mediale (GM), soleus (SO), tibialis anterior (TA), tibialis
posterior (TP).
152
Quantitative Clinical Routine Magnetic Resonance
Spectroscopy: Problems, Requirements and Solutions
J. Slotboom 1 , D. Graveron 2 , D. Stefan 3 , C. Brekenfeld 1 ,
D. van Ormondt 4
1
Institute for Diagnostic and Interventional Neuroradiology, Bern,
Switzerland, 2 Laboratoire Creatis-LRMN, CNRS UMR 5220,
Inserm U630, Université Claude Bernard LYON 1, CPE, Lyon,
France, 3 ALTER Systems, Lyon, France, 4 Applied Physics, Delft
University of Technology, Delft, Netherlands
Introduction: Localized in vivo magnetic resonance
spectroscopy (MRS) is a technique that enables the non-invasive
determination of metabolite concentrations of human tissues.
Although many advances have been made in the available
hardware, recording techniques and processing tools for MRS
in recent years, its clinical applicability is still limited. Since
the functionality of available MRS-quantification software on
commercial scanners is still limited, the clinician still needs to
export the spectrum manually, transfer it to a PC and process it
with an external, state of the art, MRS quantification program,
like e.g. jMRUI, LC-Model or TDFDFIT, which is tedious and time
consuming and error prone. On the other hand, the quantitative
results obtained by these external tools cannot be transferred
back into to PACS systems. Additionally, the above mentioned
quantification programs do not allow for the simultaneous
examination of MR-images and 1D-MRS-data within the-same
application.
Methods: Our new plug-in functionality of jMRUI enables the
user to extend the functionality of this state of the art MRS
quantification tool. In order to improve the applicability of MRS
in the clinical routine, we developed the following plug-ins that
solve the mentioned problems: I. DICOM network listener,
allowing direct network transfer of DICOM files via the DICOM-
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