Purpose: To develop and validate a novel in-vivo phosphorus-31 magnetic resonance spectroscopy (31P-MRS) method to determine the absolute concentrations of phosphocreatine [PCr], inorganic phosphate [Pi], and adenosine triphosphate [ATP] in the vastus lateralis muscle. Materials and Methods: An external 6 mL plastic vial with 850 mM of methylenediphosphonic acid (MDP), fixed to the center of a commercial dual-tuned transmit/receive surface coil, was used to calibrate metabolite concentrations from spectral areas. A 15cm diameter, 4 L cylindrical phantom (35 mM H3PO4) was scanned on a custom coil holder using the same parameters. Reproducibility of the 31P-MRS measurements was determined in volunteers (2M/3F, age = 39.2±21.9 years) while accuracy was determined using phantoms of known concentrations. Eight young subjects (24.5+4.2 years; 4M/4F) and eight older subjects (59.6+4.5 years; 4M/4F) were scanned. Student’s t-test was used to compare older versus younger subjects. Results: The percent error between the calculated and known molarity of phantoms was 3.3±1.9%. The mean coefficient of variation for the measurements of [PCr] was 5.2±3.7 %. Phosphorus metabolite concentrations, including [PCr] (25.2±3.4 mM vs. 28.5±3.4 mM, p < 0.005), [ATP] (6.68±0.84 mM vs. 7.71±0.61 mM, p<0.05) and [Pi] (3.18±0.46 mM vs. 2.56±0.55 mM, p<0.05) were significantly lower in older versus younger subjects. A significant, negative correlation was found between [PCr] and BMI (r = -0.50, p < 0.05). Conclusion: Quantitative 31P-MRS measurements reveal previously unappreciated differences in skeletal muscle phosphorus metabolite concentrations between young and older subjects and may provide unique insights when combined with other metabolic tests.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.