title: Assessing vascular response to exercise using a combination of real-time spiral phase contrast MR and noninvasive blood pressure measurements.
abstract: OBJECTIVE
  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).
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Centre for Medical Image Computing, UCL Department of Medical Physics & Bioengineering, London, United Kingdom.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Steeden
authors.forename: David
authors.initials: D
authors.lastname: Atkinson
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Taylor
authors.forename: Vivek
authors.initials: V
authors.lastname: Muthurangu
mesh_terms: D000328:Adult; D001011:Aorta / Q000473:pathology; D016477:Artifacts; D001783:Blood Flow Velocity / Q000502:physiology*; D001794:Blood Pressure; D005260:Female; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D013997:Time Factors