Selective microvascular muscle perfusion imaging in the shoulder with intravoxel incoherent motion (IVIM)

The evaluation of local muscle recruitment during a specific movement can be done indirectly by measuring changes in local blood flow. Intravoxel incoherent motion perfusion imaging exploits some properties of the magnetic resonance to measure locally microvascular perfusion, and seems ideally suited for this task. We studied the selectivity of the increase in intravoxel incoherent motion blood flow related parameter fD* in the muscles of 24 shoulders after two physical exam maneuvers, Jobe and Lift-off test (test order reversed in half of the volunteers) each held 2min against resistance. After a lift-off, IVIM blood flow-related fD* was increased in the subscapularis (in 10^-3mm²s^-1, 3.24±0.86 vs. rest 1.37±0.58, p<0.001) and the posterior bundle of deltoid (2.62±1.34 vs. rest 0.77±0.32, p<0.001). Those increases were selective when compared with other rotator cuff muscles and deltoid bundles respectively. After a Jobe test, increase in fD* was scattered within the rotator cuff muscles, but was selective for the lateral deltoid compared to the other deltoid bundles (anterior, p<0.001; posterior, p<0.05). Those results were similar when the testing order was reversed. In conclusion, this study demonstrated a selective increase in local microvascular perfusion after specific muscle testing of the shoulder muscles with IVIM. This technique has the potential to non-invasively characterize perfusion-related musculoskeletal physiological as well as pathological processes.