Multidetector-Row Computed Tomography Coronary Angiography Optimization of Image Reconstruction Phase According to the Heart Rate

Abstract

onsiderable progress has recently been achieved in the field of noninvasive imaging of the coronary arteries by computed tomography (CT). Multidetector-row CT (MDCT) scanners are equipped with thinner detectors and have a shorter rotation time, which enables considerably faster volume coverage with a thinner slice width during a single breath hold. The entire heart volume can be covered with nearly isotropic spatial resolution. By using the retrospective ECG gating technique, cardiac CT imaging can be obtained during an arbitrary cardiac period with a data acquisition window that is shorter than the rotation time of the scanner. However, taking into consideration that the inherent cardiac motion is rather large and complicated, this data acquisition window is not sufficiently short. Therefore, it is not always possible to obtain an adequate quality image, irrespective of which phase of the cardiac cycle the image is reconstructed in.Several methods have been attempted to determine the optimal phase for image reconstruction. In patients with lower heart rates (HRs), some researchers recommend image reconstruction in the slow filling period, [1][2][3][4] and adequate image quality for evaluation of stenoses and plaques can be obtained. [5][6][7] A similar phenomenon of better image quality for clinical use occurs in patients with lower HRs or those using -blockers. 8 However, -blockers are contraindicated in cases of congestive heart failure, atrioventricular block, or bronchial asthma, and the adverse reactions of contrast media can be severe in those using -blockers. 9,10 It is difficult to determine the appropriate phase for image reconstruction in patients with higher HRs, and occasionally multiple image series at different reconstruction phases have to be obtained for adequate quality image. [11][12][13] The purpose of this study was to optimize the image reconstruction phase of MDCT coronary angiography with reference to the HR by retrospectively analyzing CT and ECG data. Methods Study PopulationThe Institutional Review Board of Shiga University of Medical Science did not require approval or informed patient consent for this study, which was based on a retrospective analysis of CT images obtained in routine clinical practice during a 15-month period from January 2003 to March 2004. During this period, 58 sequential patients with suspected obstructive coronary artery disease underwent 8-row cardiac MDCT (Aquilion 8, Toshiba, Japan) for coronary angiography. The average age was 65.1 years (age range: 45-81 years) and their mean HR during the examination was 64.9 beats/min (range: 45-84 beats/min). Written informed consent for CT evaluation with contrast medium had been given by all patients. The exclusion criteria included severe arrhythmia, renal dysfunction, and known allergic reactions to the contrast medium. Background To optimize the image reconstruction phase of multidetector-row computed tomography (MDCT) coronary angiography according to the heart rate is crucial. Methods and Results Scan data were re...

Impact of beta-blockade premedication on image quality of ECG-gated thoracic aorta CT angiography

“…It is also time-consuming to control the heart rate prior to scan, specifically in institutions with high volume of scans. While significant improvement in image quality has been described with beta-blockade at coronary CTA performed by multiple investigators on single source scanners (17,18), the need for betablockade for coronary CTA performed on dualsource scanners is controversial (16,19,20). Ropers et al (16) and Scheffel et al (20) have studied image quality of coronary arteries using DSCT scanners in patients with heart rates >65 bpm.…”