title: Assessment of coronary artery stenosis severity and location: quantitative analysis of transmural perfusion gradients by high-resolution MRI versus FFR.
abstract: OBJECTIVE
  This study sought to test the hypothesis that transmural perfusion gradients (TPG) on adenosine stress myocardial perfusion cardiac magnetic resonance (CMR) predict hemodynamically significant coronary artery disease (CAD) as defined by fractional flow reserve (FFR).
  
  
  BACKGROUND
  Myocardial ischemia affects the subendocardial layers of the left ventricular myocardium earlier and more severely than the outer layers, and the identification of TPG should be sensitive and specific for the diagnosis of CAD. Previous studies have shown that high spatial resolution myocardial perfusion CMR allows quantitation of TPG between the subendocardium and the subepicardium.
  
  
  METHODS
  Sixty-seven patients (53 men, age 61 ± 9 years) underwent coronary angiography and high-resolution (1.2 × 1.2-mm in-plane) adenosine stress perfusion CMR at 3.0-T. TPG was calculated for 3 coronary territories. Visual analysis was performed to identify myocardial ischemia. FFR was measured in all vessels with ≥50% severity stenosis. FFR <0.8 was considered hemodynamically significant. In a training group of 30 patients, the optimal threshold of TPG to detect significant CAD was determined (Group 1). This threshold was then tested prospectively in the remaining 37 patients (Group 2).
  
  
  RESULTS
  In Group 1, a 20% TPG provided the best diagnostic threshold on both per-segment and per-patient analysis. Applied to Group 2, this threshold yielded a sensitivity of 0.78, specificity of 0.94, and area under the curve of 0.86 for the detection of CAD in a per-segment analysis and of 0.89, 0.83, and 0.86 in a per-patient analysis, respectively. TPG had a similar diagnostic accuracy to visual assessment. Linear regression analysis showed a relationship between TPG and FFR values, with r = 0.63 (p < 0.001).
  
  
  CONCLUSIONS
  The quantitative analysis of transmural perfusion gradients on high-resolution myocardial perfusion CMR accurately predicts hemodynamically significant CAD as defined by FFR. A TPG diagnostic threshold of 20% is as accurate as visual assessment.
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, King's College London British Heart Foundation Centre of Excellence, London, United Kingdom. amedeo.chiribiri@kcl.ac.uk
authors.forename: Amedeo
authors.initials: A
authors.lastname: Chiribiri
authors.forename: Gilion L T F
authors.initials: GL
authors.lastname: Hautvast
authors.forename: Timothy
authors.initials: T
authors.lastname: Lockie
authors.forename: Andreas
authors.initials: A
authors.lastname: Schuster
authors.forename: Boris
authors.initials: B
authors.lastname: Bigalke
authors.forename: Luca
authors.initials: L
authors.lastname: Olivotti
authors.forename: Simon R
authors.initials: SR
authors.lastname: Redwood
authors.forename: Marcel
authors.initials: M
authors.lastname: Breeuwer
authors.forename: Sven
authors.initials: S
authors.lastname: Plein
authors.forename: Eike
authors.initials: E
authors.lastname: Nagel
mesh_terms: D000241:Adenosine; D000368:Aged; D016009:Chi-Square Distribution; D017023:Coronary Angiography; D023921:Coronary Stenosis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006439:Hemodynamics; D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012189:Retrospective Studies; D012720:Severity of Illness Index; D014665:Vasodilator Agents
chemical_list: D014665:Vasodilator Agents; D000241:Adenosine