Dynamic ASL and T2∗-weighted MRI in exercising calf muscle at 7 T-A feasibility study

Abstract

Purpose: The aim of this study was to develop a measurement protocol for noninvasive simultaneous perfusion quantification and T2∗-weighted MRI acquisition in the exercising calf muscle at 7 Tesla. Methods: Using a nonmagnetic ergometer and a dedicated in-house built calf coil array, dynamic pulsed arterial spin labeling (PASL) measurements with a temporal resolution of 12 s were performed before, during, and after plantar flexion exercise in 16 healthy volunteers. Results: Postexercise peak perfusion in gastrocnemius muscle (GAS) was 27 ± 16 ml=100g=min, whereas in soleus (SOL) and tibialis anterior (TA) muscles it remained at baseline levels. T2∗-weighted and ASL time courses in GAS showed comparable times to peak of 161 ± 72 s and 167 ± 115 s, respectively. The T2∗-weighted signal in the GAS showed a minimum during exercise (88 ± 6 % of the baseline signal) and a peak during the recovery (122 ± 9%), whereas in all other muscles only a signal decrease was observed (minimum 91 ± 6% in SOL; 87 ± 8% in TA). Conclusion: We demonstrate the feasibility of dynamic perfusion quantification in skeletal muscle at 7 Tesla using PASL. This may help to better investigate the physiological processes in the skeletal muscle and also in diseases such as diabetes mellitus and peripheral arterial disease.