Christian Federau, Presenter: Nothing to Disclose

Patrick Omoumi MD, Abstract Co-Author: Nothing to Disclose

Joachim Forget MD, PhD, Abstract Co-Author: Nothing to Disclose

Jean-Baptiste Ledoux, Abstract Co-Author: Nothing to Disclose

Fabio Becce MD, Abstract Co-Author: Nothing to Disclose

To evaluate the feasibility of quantitative assessment of gradual and selective skeletal muscle activation using intravoxel incoherent motion (IVIM) MRI.

We included 6 right-handed healthy volunteers (mean age 31, 3 males). The muscle exercise consisted of selective contraction of right biceps and triceps brachii, with 2kg of weight against gravity. Two series of 12 and 24 contractions were performed for each muscle, alternating muscle between series. Images were obtained before, and 1 min 15 sec after the end of each series. The MRI acquisition consisted of 10 slices of a standard Stejskal-Tanner diffusion sequence with single shot echo planar imaging read-out, at 3 T and using an 8 multichannel receiver knee coil. 16 b-values ranging from 0 to 900s/mm2 were acquired. Other acquisition parameters were: in-plane resolution=1.6×1.6 mm2, slice thickness=5 mm, TR/TE=4000/83ms, GRAPPA acceleration factor=2, bandwidth=1302 Hz/px. IVIM perfusion fraction f and pseudo-diffusion coefficient D* were obtained by fitting the IVIM double exponential model, from which the blood-flow related parameter fD* was calculated. Transverse FSE PD morphologic sequences  were used to place ROIs.    

Both muscles showed gradual increase in blood-flow related perfusion parameters (fD*) after exercise (biceps after biceps flexion: fD*_rest=0.00133 +/- 0.00007mm2/s, fD*_2kg_12repeats=0.00139 +/- 0.00003, p=0.02; fD*_2kg_24repeats=0.00144 +/- 0.00005, p=0.01). (triceps after triceps flexion: fD*_rest=0.00140 +/- 0.0180, fD*_2kg_12repeats=0.00148 +/- 0.02331, p=0.03; fD*_2kg_24repeats=0.00153 +/- 0.0349, p=0.02). The increase was significantly correlated to the number of contractions for the triceps, and but not statistically significant for the biceps muscles (p_triceps=0.04, p_biceps=0.12). The increase of fD* was selective for the triceps 24 repeats compared to the antagonist (p=0.01), but below significance for triceps 12 repeats (p=0.11), biceps 12 repeats (p=0.29) and biceps 24 repeats (p=0.18).

IVIM perfusion imaging is a promising, non-invasive method for assessing skeletal muscle activation after exercise.

IVIM perfusion imaging could contribute to the physiological exploration of complex muscle activities (such as in sports) and in pathological conditions where a follow-up of muscle function is requested (such as after revascularization or reinnervation surgery).

Federau, C, Omoumi, P, Forget, J, Ledoux, J, Becce, F, Selective and Quantitative Functional Muscle Imaging with Intravoxel Incoherent Motion (IVIM): Initial Experience.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14010201.html