Noninvasive Assessment of Coronary Artery Disease by Multislice Spiral Computed Tomography Using a New Retrospectively ECG-Gated Image Reconstruction Techniqu-Comparison With Angiographic Results-

n recent years, coronary stent implantation has become an established method for treating patients with coronary artery disease. However, in-stent restenosis attributable to intimal hyperplasia still occurs at a relatively high rate, not only with bare metal stents but also with drug eluting stents. 1,2 Conventional coronary angiography is still the domain of the assessment of 'in-stent' restenosis. However, angiography has limitations because of its invasiveness and high medical expense. Thus, a non-invasive alternative to assess the patency of the stented arterial segment would be highly desirable.The application of multislice spiral computed tomography (MSCT) for imaging the coronary vasculature has been continuously evolving. With increasing numbers of detector rows (currently as many as 64), computed tomography (CT) scanners now provide coronary arterial images with markedly improved temporal and spatial resolution. In vitro and phantom studies on stent imaging have shown that 16-slice MSCT can adequately resolve even the lumens of stents placed within small vessels. 3 In clinical settings, however, many factors, including motion artifacts because of arrhythmia or high heart rate, coronary calcification, and Circulation Journal Vol.70, June 2006artifacts as a result of metallic material, can impair the quality of images of implanted stents. The purpose of the present study, therefore, was to determine: (i) the usefulness of 16-slice MSCT for evaluating coronary stent patency in a clinical population; and (ii) the parameters that determine the quality of stent images. Methods Patients and Study ProtocolThe study consisted of 31 patients (27 male, 4 female; average age 64±10 years; 26 patients with old myocardial infarction, 5 with stable angina) who had been treated with coronary artery stent implantation (42 total stents) between November 2002 and August 2004. The patients were scheduled for follow-up invasive coronary angiography between June 2003 and November 2004. Before their angiography, each patient underwent MSCT to assess coronary stent patency. All patients were in sinus rhythm at the time of the CT angiography, and there were no contraindications to CT imaging. Twenty-five patients had a prescan heart rate of >70 beats/min; they were given a single oral dose of 20-40 mg metoprolol 90-120 min before the CT examination. This protocol was approved by our Institutional Ethics Committee (#2002-009, Nara Medical University Ethics Committee), and written informed consent was obtained from all patients. Background Although multislice spiral computed tomography (MSCT) is a promising technique for noninvasive coronary angiography, its usefulness in patients with stent implantation remains unclear. The aim of the present study was to compare the usefulness of MSCT with that of invasive coronary angiography for evaluating coronary stent patency. Methods and ResultsThirty-one patients were enrolled after coronary stent implantation. Sixteen-slice MSCT scans were performed (39.0±21.8 days) before follow-up coro...

Section: Discussionmentioning

confidence: 99%

Usefulness of 16-Slice Multislice Spiral Computed Tomography for Follow-up Study of Coronary Stent Implantation

Watanabe

Uemura

Iwama

et al. 2006

“…[1][2][3] The CVS has also been used for radiofrequency catheter ablation, 4 mapping, 5 and defibrillation. 6,7 Visualization of the CVS has been attempted by angiography, 8,9 echocardiography 10,11 and electron-beam computed tomography (CT), 12,13 and recently contrast-enhanced multidetector row spiral computed tomography (MDCT) has been used to noninvasively visualize coronary artery stenosis by creating high-quality 3-dimensional (3-D) images, [14][15][16][17][18][19] However, there has not been a study to date that has attempted to analyze the CVS using MDCT, so the aim of the present study was to investigate the applicability and image quality of contrast-enhanced visualization of the CVS by MDCT using retrospective ECG gating. Attention was also focused on the presence and number of coronary veins on the lateral aspect of the left ventricle (LV), which are the optimal sites for placing pacing leads for LV pacing in patients with advanced heart failure.…”

mentioning

confidence: 99%

Three-Dimensional Visualization of the Coronary Venous System Using Multidetector Row Computed Tomography

Tada

Kurosaki

Naito

et al. 2005

he coronary venous system (CVS) is increasingly being used for different electrophysiologic purposes; for example, cardiac resynchronization therapy incorporating a left ventricular (LV) coronary vein lead may improve the condition of patients with severe heart failure. [1][2][3] The CVS has also been used for radiofrequency catheter ablation, 4 mapping, 5 and defibrillation. 6,7 Visualization of the CVS has been attempted by angiography, 8,9 echocardiography 10,11 and electron-beam computed tomography (CT), 12,13 and recently contrast-enhanced multidetector row spiral computed tomography (MDCT) has been used to noninvasively visualize coronary artery stenosis by creating high-quality 3-dimensional (3-D) images, [14][15][16][17][18][19] However, there has not been a study to date that has attempted to analyze the CVS using MDCT, so the aim of the present study was to investigate the applicability and image quality of contrast-enhanced visualization of the CVS by MDCT using retrospective ECG gating. Attention was also focused on the presence and number of coronary veins on the lateral aspect of the left ventricle (LV), which are the optimal sites for placing pacing leads for LV pacing in patients with advanced heart failure. Circulation Journal Vol.69, February 2005 Methods Study PopulationThis study included 70 patients who underwent MDCT as well as radiofrequency catheter ablation (51 men, 19 women; mean age, 58±9 years [range: 25-74 years]). Sixtyfive patients had paroxysmal atrial fibrillation, and 5 had left atrial tachycardia. All patients underwent MDCT to determine the morphology and size of the left atrium and pulmonary veins prior to the ablation procedure. 20 All patients had a normal ECG during sinus rhythm, and no structural abnormalities were found by physical examination and echocardiography. MDCTAfter informed written consent was obtained, MDCT was performed using a LightSpeed Ultra™ (GE Medical System, Milwaukee, WI, USA). All patients were in normal sinus rhythm at the time of MDCT image acquisition. Patients were examined while supine and all images were acquired during an inspiratory breath-hold. After determining the contrast agent transit time, we acquired MDCT data during an intravenous injection of 100 ml of the iodinated contrast agent iopromid (Ultravist 370; Schering, Berlin, Germany) at a rate of 4 ml/s. The following scanning protocol was used: 8-detector; beam collimation, 1.25 mm; pitch factor, 0.275-0.35; scan time, 0.5 or 0.6 s/rotation; ECG gate, and half-or multi-sector reconstruction. 17 The tube current was 150 mA at 140 kV to keep the radiation dose within a reasonable range. On the basis of the results of the preliminary study, the data acquisition was started 25 s after the initiation of the contrast agent. The breath-hold Circ J 2005; 69: 165 -170 (Received August 12, 2004; revised manuscript received November 17, 2004; accepted November 25, 2004 Background This study was undertaken to investigate the applicability and image quality of contrast-enhanced visualization of...

“…They reported that the image reconstruction phase determined by Method P could consistently avoid the atrial contraction period in each cardiac cycle and could provide much better image quality than the method in which the beginning of the image reconstruction phase was positioned at the midpoint between the RR intervals of the cardiac cycle. 19,20 As previously described, the point at which the reduced ejection period changes into the isovolemic relaxation period is supposed to be near the end point of the T wave. The ventricular movement is expected to be larger at the beginning of the rapid filling period than at the end of the contraction period.…”

Section: Discussionmentioning

confidence: 99%

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

Nagatani¹,

Takahashi²,

Takazakura³

et al. 2007

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...