Aim: Evaluating time and spatially resolved 1H magnetic resonance imaging (MRI) in quantifying muscle tissue phosphocreatine (PCr) kinetics (without extra hardware) and perfusion in healthy individuals and patients with type 2 diabetes mellitus (DM) .
Methods: 18 subjects were imaged in 3 groups using a 3T MRI scanner; young healthy (26y, n= 6) , old healthy (62y, n = 6) , and DM patients (66y, n = 6) . For each subject, a chemical exchange saturation transfer (CEST) MRI scan was performed in the calf every 1 min at rest (3 min) , during exercise (4 min standardized isometric plantarflexion) , and a recovery period (6 min) . Subjects also underwent mapping of skeletal muscle perfusion in a separate exercise protocol. PCr concentration maps were quantified by Bloch-McConnell fitting, and values were obtained in the medial gastrocnemius and soleus muscles.
Results: DM patients show a longer PCr recovery time τ during recovery compared to both healthy groups: young healthy τ = 47.1 ± 18.2s, old healthy τ = 41.9 ± 15.1s, and DM τ =122.2 ± 58.6s, p = 0.02 (Figure) . There is a negative correlation between PCr and perfusion during exercise in healthy groups (r = 0.38, p = 0.034) that is not significant in the DM group.
Conclusion: Dynamic PCr mapping by proton MRI in calf muscle reveals impaired energetics that is uncoupled from muscle perfusion in DM compared to healthy controls.
R.Wahidi: None. R.Li: None. M.A.Zayed: None. M.Hastings: None. J.Zheng: None.