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Morton G.,Kings College London | Morton G.,National Health Research Institute | Morton G.,Wellcome Trust and Engineering and Physical science Research Council EPSRC | Morton G.,Rayne Institute | And 46 more authors.
Journal of the American College of Cardiology | Year: 2012

Objectives: The aim of this study was to compare fully quantitative cardiovascular magnetic resonance (CMR) and positron emission tomography (PET) myocardial perfusion and myocardial perfusion reserve (MPR) measurements in patients with coronary artery disease (CAD). Background: Absolute quantification of myocardial perfusion and MPR with PET have proven diagnostic and prognostic roles in patients with CAD. Quantitative CMR perfusion imaging has been established more recently and has been validated against PET in normal hearts. However, there are no studies comparing fully quantitative CMR against PET perfusion imaging in patients with CAD. Methods: Forty-one patients with known or suspected CAD prospectively underwent quantitative 13N-ammonia PET and CMR perfusion imaging before coronary angiography. Results: The CMR-derived MPR (MPRCMR) correlated well with PET-derived measurements (MPR PET) (r = 0.75, p < 0.0001). MPRCMR and MPR PET for the 2 lowest scoring segments in each coronary territory also correlated strongly (r = 0.79, p < 0.0001). Absolute CMR perfusion values correlated significantly, but weakly, with PET values both at rest (r = 0.32; p = 0.002) and during stress (r = 0.37; p < 0.0001). Area under the receiver-operating characteristic curve for MPRPET to detect significant CAD was 0.83 (95% confidence interval: 0.73 to 0.94) and for MPRCMR was 0.83 (95% confidence interval: 0.74 to 0.92). An MPR PET ≤1.44 predicted significant CAD with 82% sensitivity and 87% specificity, and MPRCMR ≤1.45 predicted significant CAD with 82% sensitivity and 81% specificity. Conclusions: There is good correlation between MPRCMR and MPRPET. For the detection of significant CAD, MPRPET and MPRCMR seem comparable and very accurate. However, absolute perfusion values from PET and CMR are only weakly correlated; therefore, although quantitative CMR is clinically useful, further refinements are still required. © 2012 American College of Cardiology Foundation.

Sinclair M.,Kings College London | Sinclair M.,National Institute of Heath Research NIHR | Sinclair M.,Wellcome Trust and Engineering and Physical science Research Council EPSRC | Lee J.,Kings College London | And 17 more authors.
Microvascular Research | Year: 2015

Particle skimming is a phenomenon where particles suspended in fluid flowing through vessels distribute disproportionately to bulk fluid volume at junctions. Microspheres are considered a gold standard of intra-organ perfusion measurements and are used widely in studies of flow distribution and quantification. It has previously been hypothesised that skimming at arterial junctions is responsible for a systematic over-estimation of myocardial perfusion from microspheres at the subendocardium. Our objective is to integrate coronary arterial structure and microsphere distribution, imaged at high resolution, to test the hypothesis of microsphere skimming in a porcine left coronary arterial (LCA) network. A detailed network was reconstructed from cryomicrotome imaging data and a Poiseuille flow model was used to simulate flow. A statistical approach using Clopper-Pearson confidence intervals was applied to determine the prevalence of skimming at bifurcations in the LCA. Results reveal that microsphere skimming is most prevalent at bifurcations in the larger coronary arteries, namely the epicardial and transmural arteries. Bifurcations at which skimming was identified have significantly more asymmetric branching parameters. This finding suggests that when using thin transmural segments to quantify flow from microspheres, a skimming-related deposition bias may result in underestimation of perfusion in the subepicardium, and overestimation in the subendocardium. © 2015 Elsevier Inc.

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