title: Quantifying in vivo hemodynamic response to exercise in patients with intermittent claudication and abdominal aortic aneurysms using cine phase-contrast MRI.
abstract: OBJECTIVE
  To evaluate rest and exercise hemodynamics in patients with abdominal aortic aneurysms (AAA) and peripheral occlusive disease (claudicants) using phase-contrast MRI.
  
  
  METHODS
  Blood velocities were acquired by means of cardiac-gated cine phase-contrast in a 0.5 Tesla (T) open MRI. Volumetric flow was calculated at the supraceliac (SC), infrarenal (IR), and mid-aneurysm (MA) levels during rest and upright cycling exercise using an MR-compatible exercise cycle.
  
  
  RESULTS
  Mean blood flow increased during exercise (AAA: 130%, Claudicants: 136% of resting heart rate) at the SC and IR levels for AAA participants (2.6 +/- 0.6 versus 5.8 +/- 1.6 L/min, P < 0.001 and 0.8 +/- 0.4 versus 5.1 +/- 1.7 L/min, P < 0.001) and claudicants (2.3 +/- 0.5 versus 4.5 +/- 0.9 L/min, P < 0.005 and 0.8 +/- 0.2 versus 3.3 +/- 0.9 L/min, P < 0.005). AAA participants had a significant decrease in renal and digestive blood flow from rest to exercise (1.8 +/- 0.7 to 0.7 +/- 0.6 L/min, P < 0.01). The decrease in renal and digestive blood flow during exercise correlated with daily activity level for claudicants (R = 0.81).
  
  
  CONCLUSIONS
  Abdominal aortic hemodynamic changes due to lower extremity exercise can be quantified in patients with AAA and claudication using PC-MRI. The redistribution of blood flow during exercise was significant and different between the two disease states.
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, CA, USA.
authors.forename: Adam S
authors.initials: AS
authors.lastname: Tenforde
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Cheng
authors.forename: Ga-Young
authors.initials: GY
authors.lastname: Suh
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Herfkens
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Dalman
authors.forename: Charles A
authors.initials: CA
authors.lastname: Taylor
mesh_terms: D000368:Aged; D017544:Aortic Aneurysm, Abdominal / Q000150:complications* / Q000175:diagnosis*; D005080:Exercise Test; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007383:Intermittent Claudication / Q000175:diagnosis* / Q000209:etiology*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity