Assessment of metabolism and microcirculation of healthy skeletal muscles by magnetic resonance and ultrasound techniques.
OBJECTIVE
To assess metabolism and microcirculation of healthy skeletal muscle by magnetic resonance (MR) and ultrasound techniques and to compare these data with muscle histology, and anthropometric and blood parameters.


METHODS
Thirty-four healthy volunteers were selected such that their measured aerobic capacity (VO2max) per body weight ranged between 23 and 66 mL/minute/kg to render a large variability of skeletal muscle capillarization as a result of their different physical activity. We analyzed body composition, blood parameters, and skeletal muscle fiber size and capillarization in biopsies of the vastus lateralis muscle. These data were compared with knee extensor cross-sectional area (CSA) obtained by MR imaging, microcirculation of the vastus lateralis muscle by contrast-enhanced ultrasound (CEUS), and its energy and lipid metabolism measured with 31P and 1H MR spectroscopy. Statistical analysis was performed using Pearson's correlation coefficient and significance was tested at a level of .5%.


RESULTS
The variable physical activity was reflected in a large variability of vastus lateralis muscle perfusion and metabolism at rest with highest histologic capillarization and CEUS-perfusion values observed in the best-trained volunteers. Levels of high-energy phosphates, such as phosphocreatine, were positively correlated with CSA (r= .5) and histologic fiber size (r= .6 for type IIA and IIX fibers), while phosphocreatine concentration was significantly negatively correlated to myocellular lipids (r=-.6) and trimethyl ammonium containing compounds (r=-.8). Local blood volume measured in vivo with CEUS was positively correlated with several histologic capillarization parameters.


CONCLUSIONS
Dedicated MR- and CEUS-methods deliver (patho-)physiologic information about capillarization and fiber characteristics of skeletal muscles in vivo and hence establish a useful diagnostic tool for muscular diseases.
Weber
Marc-André
MA
Department of Radiology, German Cancer Research Center, Heidelberg, Germany. m.a.weber@dkfz.de
Krakowski-Roosen
Holger
H
Hildebrandt
Wulf
W
Schröder
Leif
L
Ionescu
Ingrid
I
Krix
Martin
M
Kinscherf
Ralf
R
Bachert
Peter
P
Kauczor
Hans-Ulrich
HU
Essig
Marco
M
D000328:Adult; D000368:Aged; D001706:Biopsy; D001823:Body Composition; D003287:Contrast Media; D004734:Energy Metabolism; D006801:Humans; D050356:Lipid Metabolism; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008833:Microcirculation; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D010806:Physical Education and Training; D011134:Polysaccharides; D018608:Ultrasonography, Doppler
D003287:Contrast Media; D011134:Polysaccharides; C059891:SHU 508