Abstract 20148: Noninvasive Quantification of Pressure Difference Across a Coronary Stenosis Using Phase-Contrast (PC)-MRI: Initial Patient study Using Fractional Flow Reserve as Reference
Introduction: In patients suspected of coronary artery disease (CAD) undergoing invasive coronary angiography (ICA), ~50% has nonsignificant stenoses (<50% diameter stenosis or fractional flow reserve, FFR>0.80). Recent noninvasive technique, FFRCT (coronary computed tomography angiography, CCTA with computational fluid dynamic simulations), has shown to decrease the number of unnecessary invasive procedures, however, CCTA requires exposure to ionizing radiation and is more prone to artifacts caused by calcification. In this study, we evaluate a noninvasive technique using cross-sectional 2D phase-contrast (PC)-MRI and Navier-Stokes analysis to derive pressure difference (ΔP) across a coronary stenosis, with the ultimate goal of estimating FFR. As FFR requires adenosine, which is technically challenging for PC-MRI due to high heart rates, the proposed technique mimics an instantaneous wave-free ratio (iFR) (ΔP obtained at diastole without adenosine; assuming aortic pressure of 74.2 mmHg), denoted as MR-iFR. We have previously shown the reproducibility of the technique in phantoms and healthy subjects. This work aims to evaluate its feasibility in patients.
Methods: 29 patients with known/suspected CAD, scheduled for ICA were recruited. All patients had ≥1 coronary lesion (proximal and/or middle stenosis ≤70%) detected by CCTA and/or ICA with MR imaging corresponding anatomically to invasive FFR.
Results: Good quality PC-MRI data were acquired in 25 (86%) patients where poor quality data were due to cardiac/respiratory motion. Good correlation (r=0.80; R2=0.64 (p<0.0001)) was observed between MR-iFR and FFR. Using a FFR and MR-iFR cut off of 0.80 and 0.90, respectively, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 75%, 95%, 75%, and 95%, respectively.
Conclusions: Initial patient results suggested that quantification of ΔP in diseased coronary arteries is feasible. High specificity and NPV were observed, which demonstrates the potential of the proposed technique in identifying patients with functionally nonsignificant stenoses. More patient studies with positive invasive FFRs are needed to further investigate the sensitivity of the approach.
Author Disclosures: Z. Deng: None. S. Lee: None. Z. Fan: None. C. Nguyen: None. Y. Xie: None. J. Pang: None. X. Bi: None. Q. Yang: None. B. Choi: None. J. Kim: None. B. Daniel: None. H. Chang: None. D. Li: None.
- © 2016 by American Heart Association, Inc.