Premium
Assessment of muscle oxygenation with balanced SSFP: A quantitative signal analysis
Author(s) -
Klarhöfer Markus,
Madörin Philipp,
Bilecen Deniz,
Scheffler Klaus
Publication year - 2008
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.21334
Subject(s) - steady state free precession imaging , signal (programming language) , oxygenation , nuclear magnetic resonance , chemistry , amplitude , intensity (physics) , physics , medicine , magnetic resonance imaging , radiology , computer science , quantum mechanics , programming language
Purpose To investigate the feasibility of balanced steady‐state free precession (b‐SSFP) for blood oxygenation level–dependent (BOLD) MRI during a short‐term ischemia/reactive hyperemia (RH) experiment on human calf muscles. Materials and Methods To investigate contributions to the b‐SSFP signal during an RH experiment, the relaxation times T 1 , T 2 , and T 2 *were quantified in an interleaved fashion. Data from soleus, gastrocnemius, and tibialis muscle groups of five healthy subjects were evaluated. Results During ischemia a decreased b‐SSFP signal amplitude as well as a decrease in T 2 , T 2 * , and the initial intensity I 0 was observed. RH provoked an overshoot of T 2 , T 2 * , and the b‐SSFP signal. No paradigm‐related changes in T 1 were observed. Comparing the evolution of transverse relaxation times, initial intensity, and b‐SSFP signal amplitude, we concluded that the measured b‐SSFP signal in muscle tissue is not only determined by T 2 variations but also significantly influenced by I 0 changes. These I 0 changes are attributed to spin density variations since inflow effects were suppressed by saturation bands. Conclusion b‐SSFP signal changes during a RH paradigm cannot unambiguously be assigned to oxygenation changes. Therefore, care has to be taken with their interpretation. J. Magn. Reson. Imaging 2008;27:1169–1174. © 2008 Wiley‐Liss, Inc.