Abstract 21413: Feasibility of Adenosine Stress Dynamic CT for the Assessment of Myocardial Perfusion in a Porcine Animal Model
Objective: To determine the accuracy of CT-based dynamic stress myocardial perfusion imaging to estimate myocardial blood flow (MBF) in a porcine animal model with variable degrees of coronary artery stenosis in comparison with microsphere derived MBF.
Methods and Materials: Six country pigs (28±4kg) underwent stent placement (confirmed 3.0 mm diameter) in the proximal LAD and a flow wire (Volcano, CA) was positioned within its intermediate segment. Subsequently, a balloon catheter was placed within the stent and inflated to obtain a defined luminal narrowing of the vessel diameter (50% and 75% diameter stenosis; respectively). All animals underwent adenosine-mediated (280μkg/min) dynamic stress and rest CT imaging using a second-generation Dual-Source CT system (Definition Flash, Siemens Medical Solution, Germany, 100 kV, 300 mAs, 20 cc Iopromide 300 (Ultravist 300, Bayer-Schering Pharma, Berlin) 3 ml/s with acquisitions every second for 30s). Distinct fluorescent microspheres were injected at each perfusion state in order to calculate MBF for each myocardial segment. Similarly, CT-based MBF was derived using a model-based parametric deconvolution method.
Results: All study procedures were performed without complications. Among 96 myocardial segments, there were 6 (6%) that were non-evaluable due to wire artifacts. At rest and stress, the average MBF was 93±6 and 125±11 ml/100ml/min for rest and stress imaging, respectively; and lowest in apical myocardial segments (both p<0.05). There was a strong positive association between CT-based and microsphere-based MBF (r=0.86, p<0.001) without overestimation by CT (average difference: 0.005±0.9 ml/g/min, p=0.9). In addition, CT-based MBF within myocardial segments pertaining to 50% and 75% coronary stenoses was strongly correlated with microsphere MBF (r=0.67, p=0.005) with lowest MBF at 75% luminal narrowing (2.1±0.1 vs. 1.4±0.4 vs. 0.8±0.3 ml/g/min for 0%, 50%, and 75% luminal narrowing under stress, respectively; p<0.01) similar to microsphere MBF.
Conclusions: CT derived MBF measurements under stress correlate well with microsphere MBF. Thus, dynamic stress perfusion CT may allow for assessment of hemodynamic relevance of different degrees of coronary artery stenosis.
- © 2010 by American Heart Association, Inc.