Purpose: The role of early stage functional assessment of muscle blood flow response (MFR) by dynamic muscle blood oxygen level-dependent (BOLD) magnetic resonance (MR) imaging is unknown. We investigated the effect of smoking on vascular function according to MFR derived from dynamic muscle BOLD MR imaging during postocclusive reactive hyperemia in young smokers and nonsmokers.
Methods: Sixteen healthy male volunteers (8 smokers, 8 nonsmokers; mean age, 30.4 ± 4.6 years) underwent BOLD MR imaging of the left calf muscle. During reactive hyperemia provoked by a cuff-compression technique, we measured muscle BOLD (mB) using a 3-tesla single-shot multi-echo gradient-echo echo-planar imaging sequence. The 2 key mB variables in the reactive hyperemic phase that we studied were times to half hyperemic peak (T_1/2peak) and peak (TTP), each measured from cuff deflation. We used the Welch test to assess differences in these between smokers and nonsmokers.
Results: T_1/2peak and TTP were significantly longer in smokers (P < 0.05) in reactive hyperemia. T_1/2peak was 13.8 ± 5.4 s in smokers and 7.6 ± 1.5 s in nonsmokers, and TTP was 67.5 ± 18.8 s in smokers and 45.4 ± 7.1 s in nonsmokers.
Conclusion: Dynamic BOLD MR imaging of calf muscle during postocclusive reactive hyperemia demonstrated statistically significant differences in T_1/2peak and TTP between young smokers and nonsmokers, indicating the presence of early stage smoking-related deterioration in MFR.