Assessing Vascular Response To Exercise Using a Combination of Real-Time Spiral Phase Contrast MR and Noninvasive Blood Pressure Measurements

Purpose: To measure the hemodynamic response to exercise using real-time velocity mapping magnetic resonance imaging (MRI), incorporating a high temporal resolution spiral phase contrast (PC) sequence accelerated with sensitivity encoding (SENSE). Materials and Methods: Twenty healthy adults underwent MRI at rest and during supine exercise at two different exercise levels. Flow volumes were assessed in the ascending aorta using a spiral SENSE real-time PC sequence. The sequence was validated at rest against a vendor supplied gated PC sequence, and also at rest and during exercise against left ventricular volumes assessed using a radial k-t SENSE real-time sequence. Combining the measured flow volumes with simultaneous oscillometric blood pressure measurements, enabled the noninvasive calculations of systemic vascular resistance (SVR) and arterial compliance (C). Results: Measured flow volumes correlated very well between the sequences at rest and during exercise. Cardiac output (CO) and heart rate were found to significantly increase during exercise, while SVR and C were found to decrease significantly. Conclusion: Hemodynamic response to exercise can be accurately quantified using a high temporal resolution spiral SENSE real-time flow imaging. This may allow early detection of hypertension and a greater understanding of the early changes in this condition.