Assessment of muscle oxygenation with balanced SSFP: A quantitative signal analysis

✍ Scribed by Markus Klarhöfer; Philipp Madörin; Deniz Bilecen; Klaus Scheffler

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 642 KB
• Volume: 27
• Category: Article
• ISSN: 1053-1807
• DOI: 10.1002/jmri.21334

✦ Synopsis

Abstract

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 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, and the initial intensity I~0~ was observed. RH provoked an overshoot of T~2~, T, 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.