title: Relative myocardial blood flow by dynamic computed tomographic perfusion imaging predicts hemodynamic significance of coronary stenosis better than absolute blood flow.
abstract: OBJECTIVE
  Quantitative myocardial perfusion imaging by computed tomography (CT) was recently introduced to calculate myocardial blood flow (MBF). Because absolute MBF thresholds may be affected by technique, methodology, and the microvasculature, we investigated whether a relative measure of MBF improves accuracy to identify hemodynamically significant coronary stenosis.
  
  
  METHODS
  In this prospective study, 42 patients (mean [SD] age, 62.3[8.7] years; 8 women) with suspected or known coronary disease underwent dynamic CT myocardial perfusion imaging using adenosine vasodilation, before invasive angiography (coronary angiography) with fractional flow reserve (FFR). Within each myocardial territory MBF, the MBF relative to remote myocardium (MBFratio) was calculated and compared with coronary angiography and FFR.
  
  
  RESULTS
  Of the 91 vessels interrogated by FFR (median, 0.81; interquartile range, 0.73-0.94), 45 vessels (49%) had an FFR value lower than 0.8 and were considered hemodynamically significant. Hyperemic MBF was lower in ischemic territories: 75.6 ± 22.5 mL per 100 mL/min versus 98.3 ± 23.1 mL per 100 mL/min (P < 0.0001). The MBFratio correlated better with FFR (P = 0.76) than the absolute MBF did (P = 0.52). Receiver operating curve analysis showed better discrimination by MBFratio: area under the curve of 0.85 versus 0.75 (P = 0.02). The MBF of remote myocardium varied between 60.7 and 167.2 mL per 100 mL/min and was lower in patients without heart rate acceleration (P = 0.0035).
  
  
  CONCLUSIONS
  The MBFratio seems to better identify hemodynamically significant coronary artery disease than does the absolute MBF determined by dynamic CT perfusion imaging. This may be caused by microvascular status or related to the methodology.
authors.affiliation: From the Departments of *Radiology, and †Cardiology, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Atsushi K
authors.initials: AK
authors.lastname: Kono
authors.forename: Adriaan
authors.initials: A
authors.lastname: Coenen
authors.forename: Marisa
authors.initials: M
authors.lastname: Lubbers
authors.forename: Akira
authors.initials: A
authors.lastname: Kurata
authors.forename: Alexia
authors.initials: A
authors.lastname: Rossi
authors.forename: Anoeshka
authors.initials: A
authors.lastname: Dharampal
authors.forename: Marcel
authors.initials: M
authors.lastname: Dijkshoorn
authors.forename: Robert-Jan
authors.initials: RJ
authors.lastname: van Geuns
authors.forename: Gabriel P
authors.initials: GP
authors.lastname: Krestin
authors.forename: Koen
authors.initials: K
authors.lastname: Nieman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017023:Coronary Angiography / Q000379:methods*; D003326:Coronary Circulation / Q000502:physiology*; D023921:Coronary Stenosis / Q000000981:diagnostic imaging*; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012039:Regional Blood Flow / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*