Abstract
To test the accuracy of quantification of myocardial perfusion imaging (MPI) using computed tomography (CT) in ex-vivo porcine models. Five isolated porcine hearts were perfused according to Langendorff. Hearts were perfused using retrograde flow through the aorta and blood flow, blood pressure and heart rate were monitored throughout the experiment. An inflatable cuff was placed around the circumflex (Cx) artery to create stenosis grades which were monitored using a pressure wire, analysing perfusion at several fractional flow reserve values of 1.0, 0.7, 0.5, 0.3, and total occlusion. Second-generation dual-source CT was used to acquire dynamic MPI in shuttle mode with 350 mAs/rot at 100 kVp. CT MPI was performed using VPCT myocardium software, calculating myocardial blood flow (MBF, ml/100 ml/min) for segments perfused by Cx artery and non-Cx myocardial segments. Microspheres were successfully infused at three stenosis grades in three of the five hearts. Heart rate ranged from 75 to 134 beats per minute. Arterial blood flow ranged from 0.5 to 1.4 l min and blood pressure ranged from 54 to 107 mmHg. MBF was determined in 400 myocardial segments of which 115 were classified as ‘Cx-territory’. MBF was significantly different between non-Cx and Cx segments at stenosis grades with an FFR ≤0.70 (Mann–Whitney U test, p < 0.05). MBF showed a moderate correlation with microsphere MBF for the three individual hearts (Pearson correlation 0.62–0.76, p < 0.01). CT MPI can be used to determine regional differences in myocardial perfusion parameters, based on severity of coronary stenosis. Significant differences in MBF could be measured between non-ischemic and ischemic segments.
Highlights
Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.Myocardial perfusion imaging (MPI) using computed tomography (CT) has gained interest in recent years, due to new CT scan techniques on state-of-the-art systems
Other non-invasive imaging techniques, like single photon emission computed tomography, magnetic resonance imaging (MRI) and positron emission tomography have proven their value in the detection of myocardial perfusion defects [1]
In an ex-vivo model, CT perfusion parameters can be tested against microsphere measurements as a reference standard for absolute myocardial blood flow (MBF) In this porcine heart study we aimed to validate the quantification of MBF in dynamic CT MPI at second-generation dual-source CT, compared to FFR and microsphere-derived MBF as reference standards, with the final aim to derive MBF cut-off values for hemodynamically significant CAD
Summary
Myocardial perfusion imaging (MPI) using computed tomography (CT) has gained interest in recent years, due to new CT scan techniques on state-of-the-art systems. Other non-invasive imaging techniques, like single photon emission computed tomography, magnetic resonance imaging (MRI) and positron emission tomography have proven their value in the detection of myocardial perfusion defects [1]. CT angiography can reliably detect and exclude coronary atherosclerosis [2]. Rossi et al provided an extensive overview of the possibilities of new CT techniques in stress CT MPI analysis [3]. One of the promising CT MPI techniques is quantitative dynamic CT MPI. In dynamic CT MPI, images are acquired at every second heartbeat, resulting in information about the myocardial inflow and outflow of contrast media
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