title: Coronary microvascular functional reserve: quantification of long-term changes with electron-beam CT preliminary results in a porcine model.
abstract: OBJECTIVE
  To evaluate the ability of electron-beam computed tomography (CT) to help quantify long-term changes in coronary microvascular functional reserve in a porcine model.
  
  
  METHODS
  Electron-beam CT-based intramyocardial blood volume and perfusion and Doppler ultrasonography (US)-based intracoronary blood flow were obtained in 13 pigs at baseline and again 3 months later. Measurements were obtained at rest and after the administration of adenosine. The short-term variation during 30 minutes of electron-beam CT measurements was assessed in nine additional pigs.
  
  
  RESULTS
  Short-term variation of blood volume and perfusion averaged 8% and 9%, respectively, and was similar for both weight groups at rest and after adenosine administration. At rest, intracoronary blood flow, blood volume, and perfusion remained unchanged from baseline to follow-up. Long-term increases (percentage change with adenosine relative to that at rest) in blood volume and perfusion reserves were consistent with increasing intracoronary blood flow reserves. Despite these long-term changes in intracoronary blood flow, blood volume, and perfusion, the blood volume-to-perfusion relationship suggests a similar blood volume distribution among different microvascular functional components in normal porcine myocardium at both weight groups.
  
  
  CONCLUSIONS
  Electron-beam CT may be of value for quantifying long-term changes in intramyocardial microvascular function.
authors.affiliation: Department of Physiology, Mayo Clinic and Foundation, 200 First St SW, Alfred 2-409, Rochester, MN 55905, USA.
authors.forename: S
authors.initials: S
authors.lastname: Möhlenkamp
authors.forename: T R
authors.initials: TR
authors.lastname: Behrenbeck
authors.forename: A
authors.initials: A
authors.lastname: Lerman
authors.forename: L O
authors.initials: LO
authors.lastname: Lerman
authors.forename: V S
authors.initials: VS
authors.lastname: Pankratz
authors.forename: P F
authors.initials: PF
authors.lastname: Sheedy
authors.forename: A L
authors.initials: AL
authors.lastname: Weaver
authors.forename: E L
authors.initials: EL
authors.lastname: Ritman
mesh_terms: D000818:Animals; D017023:Coronary Angiography / Q000379:methods*; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000502:physiology; D006439:Hemodynamics; D008297:Male; D008833:Microcirculation; D023421:Models, Animal; D013552:Swine; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D018608:Ultrasonography, Doppler