Real-time cine first-pass perfusion imaging enables rapid detection of functionally significant high-grade coronary stenosis
Journal of Cardiovascular Magnetic Resonance volume 17, Article number: O12 (2015)
Among the spectrum of patients with coronary artery disease (CAD), those suffering from high-grade stenosis are at a significantly elevated risk for adverse events . Such high-grade disease may result in the so-called "coronary steal" phenomenon under vasodilator stress  thereby inducing wall-motion abnormalities (WMAs) in the affected territories, referred to as transient ischemic dilation. We developed a "real time" cine first-pass perfusion (FPP) CMR method for concurrent imaging of myocardial function and perfusion. We hypothesized that this method is capable of simultaneously capturing stress-induced perfusion defects and WMAs in a single ungated scan.
Canines (n=9) with surgically implemented reversible stenosis below the first diagonal along the left anterior descending (LAD) artery (≈90% stenosis) were studied at 3T. Real-time adenosine stress/rest cine perfusion data was acquired using an ungated continuously-sampled FPP sequence without saturation recovery preparation [3, 4]. The T1-weighted acquisition scheme used a steady-state FLASH sequence with 3-5 slice coverage and no time-gap in between consecutive slice-interleaved radial readouts, acquiring 5,000 projections per slice during the 40-second real-time FPP scan (flip: 30°, echo spacing: 2.7 ms, in-plane resolution: 1.4x1.4 mm2). Retrospective cardiac self-gating was performed automatically using a high temporal-resolution reconstruction of the mid slice at low spatial resolution. The self-gating information was then used to perform a cardiac phase-resolved reconstruction of the FPP data for all slices at high resolution employing a compressed sensing approach. WM for the cine perfusion images was scored on a standard 1-4 scale. To test the clinical feasibility of this approach, patients (n=3) with known high-grade (≥90%) right coronary artery (RCA) stenosis were studied.
Real-time stress FPP scans in stenotic dogs (Fig. 1) showed worsening of WM in the perfusion defect territories compared to resting function, consistent with ischemic dilation (slice-averaged stress WM score for defect region: 2.8 vs. 1.6 for rest; p < 0.05). The close agreement of WMA vs. standard cine (Fig. 1) indicates the high temporal resolution of the real-time method. The mid-slice inferior perfusion defect in the example patient study (Fig. 2) coincides with the WMA (larger LV cavity area) compared to rest function, consistent with the angiogram. The other 2 patients showed similar results.
We presented a multi-slice cine FPP method capable of simultaneous detection of stress-induced perfusion defects and WMAs in a single ungated scan using continuous acquisition (<1 minute). Our initial results demonstrate that worsening of WM (compared to rest) in the perfusion defect territories seen in the real-time stress cine FPP scan may be a marker of severe CAD.
American Heart Association Scientist Development Grant 14SDG20480123; NIH National Heart, Lung and Blood Institute grant nos. K99 HL124323-01, R01 HL038698-18, R01 HL091989-05, R01 HL090957-01.
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Sharif, B., Arsanjani, R., Yang, HJ. et al. Real-time cine first-pass perfusion imaging enables rapid detection of functionally significant high-grade coronary stenosis. J Cardiovasc Magn Reson 17 (Suppl 1), O12 (2015). https://doi.org/10.1186/1532-429X-17-S1-O12