Abstract
Ischemic heart disease is the globally leading cause of death. When using coronary CT angiography, the functional hemodynamics within the myocardium remain uncertain. In this study myocardial CT perfusion imaging using iodine contrast agent demonstrated to strongly improve the assessment of myocardial disorders. However, a retrieval of such dynamics using Hounsfield units from conventional CT poses concerns with respect to beam-hardening effects and low contrast-to-noise ratio (CNR). Dual-energy CT offers novel approaches to overcome aforementioned limitations. Quantitative peak enhancement, perfusion, time to peak and iodine volume measurements inside the myocardium were determined resulting in 0.92 mg/ml, 0.085 mg/ml/s 17.12 s and 29.89 mg/ml*s, respectively. We report on the first extensive quantitative and iodine-based analysis of myocardial dynamics in a healthy porcine model using a dual-layer spectral CT. We further elucidate on the potential of reducing the radiation dose from 135 to 18 mGy and the contrast agent volume from 60 to 30 mL by presenting a two-shot acquisition approach and measuring iodine concentrations in the myocardium in-vivo down to 1 mg/ml, respectively. We believe that dynamic quantitative iodine perfusion imaging may be a highly sensitive tool for the precise functional assessment and monitoring of early myocardial ischemia.
Highlights
In 2015 approximately 15.9 million myocardial infarctions occurred worldwide[1]
(ECG)-triggered dynamic axial scans were adjusted to the cardiac cycle with an increment of zero, with the scanning area covering the mid part of the left ventricular myocardium
We showed that by using a state-of-the-art dual-energy perfusion computed tomography (CT) imaging technique, it is possible to deduce absolute iodine-based flow dynamics of the heart, arteries and myocardium
Summary
In 2015 approximately 15.9 million myocardial infarctions occurred worldwide[1]. Thereby ischemic heart disease is the most common cause of death (7.249 million deaths worldwide in 2008) accounting for 12.7% of the total global mortality[2]. Sellerer et al showed an improved root mean square deviation (RMSD) of observed iodine concentrations (with respect to true values) for different measurement configurations using a modern clinical DLCT system[18] This is of particular importance, as the quantification accuracy of iodine densities in regions of low contrast agent accumulation like in the myocardium plays a crucial role in the generation of our results. Based on the accuracy and consistency of determining low iodine densities with modern dual-energy systems, we suggest that dynamic quantitative iodine perfusion imaging may be a highly sensitive tool for the precise functional assessment and monitoring of early myocardial ischemia, if a valid database for stress and/or rest can be established[18]
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