![]() Two cohorts of patients were sequentially included. In addition, patients with intrascan mild heart rhythm abnormalities leading to motion artifacts such as premature beats and heart rate <40 bpm were excluded. Patients with diabetes, left ventricular hypertrophy, and with obstructive (≥50% stenosis) atherosclerotic coronary lesions were also excluded. ![]() Additional exclusion criteria comprised a body mass index >32 kg/m 2, a history of previous myocardial infarction, percutaneous or surgical coronary revascularization, severe valve disease, chronic heart failure, chronic obstructive pulmonary disease, or high degree atrioventricular block. All patients included were >18 years old, in sinus rhythm, able to maintain a breath-hold for ≥15 seconds, without a history of contrast related allergy, renal failure, or haemodynamic instability. The present was a single-center, investigator-driven, observational study, that involved consecutive patients without a history of CAD who were referred for CTCA evaluation at our institution due to atypical chest pain and evidence of a normal stress-rest single-photon emission computed tomography (SPECT) within the previous 3 months. We therefore sought to explore the ability of DE CTP to mitigate the presence of BHA in a non-diabetic population with normal myocardial perfusion and without evidence of coronary artery disease (CAD). Dual energy (DE) CT imaging has the potential to attenuate or even elucidate some of these technical issues observed in SE imaging, mainly driven by its ability to obtain synthesized monochromatic image reconstructions ( 7, 9). These artifacts are related to the polychromatic nature of X-rays and to the energy-dependency of X-ray attenuation, and lead to a significant drop in attenuation levels in areas adjacent to highly enhanced structures, commonly resembling perfusion defects in certain left ventricular segments during CTCA ( 8). Nevertheless, the assessment of myocardial perfusion using conventional single energy (SE) acquisitions is influenced by the presence of beam hardening artifacts (BHA) ( 7, 8). Myocardial perfusion imaging by means of computed tomography (CT) shows promise to provide an incremental diagnostic and prognostic value over computed tomography coronary angiography (CTCA) ( 3- 6). Accepted for publication Jan 23, 2015.ĭuring the past decade, the poor relationship between the degree of stenosis and the presence of ischemia has driven the need to assess the physiological impact of a given atherosclerotic lesion, particularly of moderate lesions ( 1, 2). ![]() Keywords: Myocardial perfusion perfusion defect myocardial infarction ischemia cardiac computed tomography (CT) Compared to DE reconstructions at the best energy level (70 keV), SE acquisitions showed no significant differences overall regarding myocardial SD levels among the reference segments.Ĭonclusions: BHA that influence the assessment of myocardial perfusion can be attenuated using DE at 70 keV or higher. Significant differences were identified between the PB segment and the reference segment among the lower energy levels, whereas at ≥70 keV myocardial SD levels were similar. Myocardial signal-to-noise ratio was not significantly influenced by the energy level applied, although 70 keV was identified as the energy level with the best overall signal-to-noise ratio. Among the DE group, myocardial SD levels and myocardial SD ratio evaluated at the reference segment were higher at low energy levels, with significantly lower SD levels at increasing energy levels. Myocardial signal density (SD) levels were evaluated in 280 basal segments among the DE group (140 PB segments for each energy level from 40 to 100 keV and 140 reference segments), and in 40 basal segments (at the same locations) among the SE group. Results: Demographical characteristics were similar between groups, as well as the heart rate and the effective radiation dose. The study group was acquired using DE and the control group using SE imaging. Methods: Consecutive patients without history of coronary artery disease who were referred for computed tomography coronary angiography (CTCA) due to atypical chest pain and a normal stress-rest SPECT and had absence or mild coronary atherosclerosis constituted the study population. ![]() We therefore sought to explore the ability of dual energy (DE) CTP to attenuate the presence of BHA. Background: Myocardial computed tomography perfusion (CTP) using conventional single energy (SE) imaging is influenced by the presence of beam hardening artifacts (BHA), occasionally resembling perfusion defects and commonly observed at the left ventricular posterobasal wall (PB).
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