Dynamic DTI (dDTI) shows differing temporal activation patterns in post-exercise skeletal muscles.
OBJECTIVE
To assess post-exercise recovery of human calf muscles using dynamic diffusion tensor imaging (dDTI).


METHODS
DTI data (6 directions, b = 0 and 400 s/mm2) were acquired every 35 s from seven healthy men using a 3T MRI, prior to (4 volumes) and immediately following exercise (13 volumes, ~7.5 min). Exercise consisted of 5-min in-bore repetitive dorsiflexion-eversion foot motion with 0.78 kg resistance. Diffusion tensors calculated at each time point produced maps of mean diffusivity (MD), fractional anisotropy (FA), radial diffusivity (RD), and signal at b = 0 s/mm2(S0). Region-of-interest (ROI) analysis was performed on five calf muscles: tibialis anterior (ATIB), extensor digitorum longus (EDL) peroneus longus (PER), soleus (SOL), and lateral gastrocnemius (LG).


RESULTS
Active muscles (ATIB, EDL, PER) showed significantly elevated initial MD post-exercise, while predicted inactive muscles (SOL, LG) did not (p < 0.0001). The EDL showed a greater initial increase in MD (1.90 × 10-4mm2/s) than ATIB (1.03 × 10-4mm2/s) or PER (8.79 × 10-5mm2/s) (p = 7.40 × 10-4), and remained significantly elevated across more time points than ATIB or PER. Significant increases were observed in post-exercise EDL S0relative to other muscles across the majority of time points (p < 0.01 to p < 0.001).


CONCLUSIONS
dDTI can be used to differentiate exercise-induced changes between muscles. These differences are suggested to be related to differences in fiber composition.
McMaster School of Biomedical Engineering, McMaster University, ETB-406 1280 Main St. West, Hamilton, ON, L8S 4K1, Canada.|Imaging Research Centre, St. Joseph's Healthcare, Hamilton, ON, Canada.
Conrad
C
Rockel
McMaster School of Biomedical Engineering, McMaster University, ETB-406 1280 Main St. West, Hamilton, ON, L8S 4K1, Canada.|Imaging Research Centre, St. Joseph's Healthcare, Hamilton, ON, Canada.
Alireza
A
Akbari
McMaster School of Biomedical Engineering, McMaster University, ETB-406 1280 Main St. West, Hamilton, ON, L8S 4K1, Canada.|Division of Physical Medicine and Rehabilitation, Department of Medicine, University of Toronto, Toronto, ON, Canada.
Dinesh A
DA
Kumbhare
McMaster School of Biomedical Engineering, McMaster University, ETB-406 1280 Main St. West, Hamilton, ON, L8S 4K1, Canada. nosewor@mcmaster.ca.|Imaging Research Centre, St. Joseph's Healthcare, Hamilton, ON, Canada. nosewor@mcmaster.ca.|Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON, Canada. nosewor@mcmaster.ca.|Department of Radiology, McMaster University, Hamilton, ON, Canada. nosewor@mcmaster.ca.|Department of Electrical and Computer Engineering, McMaster University, Hamilton, ON, Canada. nosewor@mcmaster.ca.
Michael D
MD
Noseworthy
D000328:Adult; D016880:Anisotropy; D015992:Body Mass Index; D038524:Diffusion Magnetic Resonance Imaging; D056324:Diffusion Tensor Imaging; D015444:Exercise; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000502:physiology*; D009132:Muscles; D055815:Young Adult
DTI; Exercise; Human; Recovery; Skeletal muscle; Time course