Figure 4

Global and regional PCr recovery using PCr imaging. (a) shows an image of calf muscle for anatomical reference and the muscle ROIs drawn for soleus (SOL), gastrocnemius medial (GM) and gastrocnemius lateral (GL). Sub-figures (b) and (c) show global and regional PCr recovery time constraints assessed using ³¹P-MRI data from a representative HF patient and healthy volunteer by fitting phase III data to Eq. 1. The PCr recovery time constants are significantly delayed (~ 60–70 s) compared to healthy volunteers (~ 20- 25 s). The PCr recovery time in specific muscles (d) GM (e) SOL and (f) GL shows increased depletion and slower recovery in GM and GL muscle groups, suggesting glycolytic metabolism from type II fibers’.