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  • Title: Accuracy of dynamic computed tomography adenosine stress myocardial perfusion imaging in estimating myocardial blood flow at various degrees of coronary artery stenosis using a porcine animal model.
    Author: Bamberg F, Hinkel R, Schwarz F, Sandner TA, Baloch E, Marcus R, Becker A, Kupatt C, Wintersperger BJ, Johnson TR, Theisen D, Klotz E, Reiser MF, Nikolaou K.
    Journal: Invest Radiol; 2012 Jan; 47(1):71-7. PubMed ID: 22178894.
    Abstract:
    OBJECTIVE: To determine the accuracy of computed tomography (CT) dynamic stress myocardial perfusion imaging to estimate myocardial blood flow (MBF) in a porcine animal model with variable degrees of induced coronary artery stenosis in comparison with microsphere-derived MBF. METHODS AND MATERIALS: Seven domestic pigs (36 ± 4 kg) received stents (confirmed 3.0 mm diameter) in the left anterior descending coronary artery distal to first diagonal branch. A balloon catheter was placed within the stent and inflated to various degrees to obtain a defined luminal narrowing (50% and 75% diameter stenosis) as confirmed by intra-arterial flow wire measurement. All models underwent adenosine-mediated (140 μg/kg/min) dynamic stress and rest myocardial perfusion CT imaging using a dual-source CT scanner (shuttle-mode with 100 kV/300 mAs, 20 mL iopromide) with prospective acquisitions every second heartbeat for 30 seconds. CT-estimated MBF (MBFCT) was calculated using a model-based parametric deconvolution method and correlated to that of fluorescent microspheres (MBFmic) injected at each perfusion state. RESULTS: All study procedures were performed without complications, and all animals completed the study protocol. Among 448 myocardial segments, 31 (7%) were considered nonevaluable because of motion artifacts. With stress, MBFCT increased significantly (1.10 ± 0.25 vs. 0.80 ± 0.28 mL/g/min, P < 0.001; at stress and rest, respectively) in all myocardial segments and correlated with MBFmic (r = 0.67, P < 0.001). MBFCT overestimated MBFmic, independently of adenosine-stress and degree of coronary stenosis (β = 2.3, 95% confidence interval: 1.81-2.79 mL/g/min, P < 0.001). Although there were no differences in MBFCT between 50% and 75% coronary stenosis at rest (0.01 ± 0.08 mL/g/min, P = 0.86), MBFCT was significantly lower at 75% than at 50% under stress conditions (0.53 ± 0.19 vs. 0.71 ± 0.24 mL/g/min, P = 0.002). CONCLUSIONS: CT-derived MBF measurements at rest and stress with varying degrees of coronary stenosis show a valid difference but an underestimated correlation with microsphere-derived MBF in a porcine animal model.
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