title: T(2) preparation method for measuring hyperemic myocardial O(2) consumption: in vivo validation by positron emission tomography.
abstract: OBJECTIVE
  To validate a new T(2) -prepared method for the quantification of regional myocardial O(2) consumption during pharmacologic stress with positron emission tomography (PET).
  
  
  METHODS
  A T(2) prepared gradient-echo sequence was modified to measure myocardial T(2) within a single breath-hold. Six beagle dogs were randomly selected for the induction of coronary artery stenosis. Magnetic resonance imaging (MRI) experiments were performed with the T(2) imaging and first-pass perfusion imaging at rest and during either dobutamine- or dipyridamole-induced hyperemia. Myocardial blood flow (MBF) was quantified using a previously developed model-free algorithm. Hyperemic myocardial O(2) extraction fraction (OEF) and consumption (MVO(2) ) were calculated using a two-compartment model developed previously. PET imaging using (11) C-acetate and (15) O-water was performed in the same day to validate OEF, MBF, and MVO(2) measurements.
  
  
  RESULTS
  The T(2) -prepared mapping sequence measured regional myocardial T(2) with a repeatability of 2.3%. By myocardial segment-basis analysis, MBF measured by MRI is closely correlated with that measured by PET (R(2) = 0.85, n = 22). Similar correlation coefficients were observed for hyperemic OEF (R(2) = 0.90, n = 9, mean difference of PET - MRI = -2.4%) and MVO(2) (R(2) = 0.83, n = 7, mean difference = 4.2%).
  
  
  CONCLUSIONS
  The T(2) -prepared imaging method may allow quantitative estimation of regional myocardial oxygenation with relatively good accuracy. The precision of the method remains to be improved.
authors.affiliation: Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, Missouri 63110, USA.
authors.forename: Kyle S
authors.initials: KS
authors.lastname: McCommis
authors.forename: Robert
authors.initials: R
authors.lastname: O'Connor
authors.forename: Dana R
authors.initials: DR
authors.lastname: Abendschein
authors.forename: David
authors.initials: D
authors.lastname: Muccigrosso
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Gropler
authors.forename: Jie
authors.initials: J
authors.lastname: Zheng
mesh_terms: D000465:Algorithms; D000818:Animals; D003331:Coronary Vessels; D004285:Dogs; D006331:Heart Diseases / Q000378:metabolism*; D006940:Hyperemia / Q000378:metabolism*; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D049268:Positron-Emission Tomography; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D010100:Oxygen