Published in:
01-08-2010 | Musculoskeletal
3D 23Na MRI of human skeletal muscle at 7 Tesla: initial experience
Published in: European Radiology | Issue 8/2010
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Objective
To evaluate healthy skeletal muscle pre- and post-exercise via 7 T 23Na MRI and muscle proton T2 mapping, and to evaluate diabetic muscle pre- and post-exercise via 7 T 23Na MRI.
Methods
The calves of seven healthy subjects underwent imaging pre- and post-exercise via 7 T 23Na MRI (3D fast low angle shot, TR/TE = 80 ms/0.160 ms, 4 mm × 4 mm × 4 mm) and 1 week later by 1H MRI (multiple spin-echo sequence, TR/TE = 3,000 ms/15–90 ms). Four type 2 diabetics also participated in the 23Na MRI protocol. Pre- and post-exercise sodium signal intensity (SI) and proton T2 relaxation values were measured/calculated for soleus (S), gastrocnemius (G), and a control, tibialis anterior (TA). Two-tailed t tests were performed.
Results
In S/G in healthy subjects post-exercise, sodium SI increased 8–13% (p < 0.03), then decreased (t
1/2 = 22 min), and 1H T2 values increased 12–17% (p < 0.03), then decreased (t
1/2 = 12–15 min). In TA, no significant changes in sodium SI or 1H T2 values were seen (−2.4 to 1%, p > 0.17). In S/G in diabetics, sodium SI increased 10–11% (p < 0.04), then decreased (t
1/2 = 27–37 min) without significant change in the TA SI (−3.6%, p = 0.066).
Conclusion
It is feasible to evaluate skeletal muscle via 3D 23Na MRI at 7 T. Post-exercise muscle 1H T2 values return to baseline more rapidly than sodium SI. Diabetics may demonstrate delayed muscle sodium SI recovery compared with healthy subjects.