title: Clinical value of absolute quantification of myocardial perfusion with (15)O-water in coronary artery disease.
abstract: BACKGROUND
  The standard interpretation of perfusion imaging is based on the assessment of relative perfusion distribution. The limitations of that approach have been recognized in patients with multivessel disease and endothelial dysfunction. To date, however, no large clinical studies have investigated the value of measuring quantitative blood flow and compared that with relative uptake.
  
  
  RESULTS
  One hundred four patients with moderate (30%-70%) pretest likelihood of coronary artery disease (CAD) underwent PET imaging during adenosine stress using (15)O-water and dynamic imaging. Absolute myocardial blood flow was calculated from which both standard relative myocardial perfusion images and images scaled to a known absolute scale were produced. The patients and the regions then were classified as normal or abnormal and compared against the reference of conventional angiography with fractional flow reserve. In patient-based analysis, the positive predictive value, negative predictive value, and accuracy of absolute perfusion in the detection of any obstructive CAD were 86%, 97%, and 92%, respectively, with absolute quantification. The corresponding values with relative analysis were 61%, 83%, and 73%, respectively. In region-based analysis, the receiver operating characteristic curves confirmed that the absolute quantification was superior to relative assessment. In particular, the specificity and positive predictive value were low using just relative differences in flow. Only 9 of 24 patients with 3-vessel disease were correctly assessed using relative analysis.
  
  
  CONCLUSIONS
  The measurement of myocardial blood flow in absolute terms has a significant impact on the interpretation of myocardial perfusion. As expected, multivessel disease is more accurately detected.
authors.affiliation: Turku PET Centre, University of Turku, Turku, Finland. sami.kajander@tyks.fi
authors.forename: Sami A
authors.initials: SA
authors.lastname: Kajander
authors.forename: Esa
authors.initials: E
authors.lastname: Joutsiniemi
authors.forename: Markku
authors.initials: M
authors.lastname: Saraste
authors.forename: Mikko
authors.initials: M
authors.lastname: Pietilä
authors.forename: Heikki
authors.initials: H
authors.lastname: Ukkonen
authors.forename: Antti
authors.initials: A
authors.lastname: Saraste
authors.forename: Hannu T
authors.initials: HT
authors.lastname: Sipilä
authors.forename: Mika
authors.initials: M
authors.lastname: Teräs
authors.forename: Maija
authors.initials: M
authors.lastname: Mäki
authors.forename: Juhani
authors.initials: J
authors.lastname: Airaksinen
authors.forename: Jaakko
authors.initials: J
authors.lastname: Hartiala
authors.forename: Juhani
authors.initials: J
authors.lastname: Knuuti
mesh_terms: D001783:Blood Flow Velocity; D015331:Cohort Studies; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003326:Coronary Circulation / Q000502:physiology*; D025401:Echocardiography, Stress / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods; D008297:Male; D010477:Perfusion / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
chemical_list: D003287:Contrast Media