Intra-Cycle Motion Correction in Coronary CT Angiography

Coronary computed tomography angiography (CCTA) has demonstrated high diagnostic performance for coronary lesions detection. However, coronary artery motion blurring, related to high or variable heart rate (HR) is a common drawback. Recently, a novel intracycle motion-correction (MC) algorithm has been developed. Aim of the present review is to evaluate the published literature regarding the impact of MC algorithm compared with standard reconstruction on diagnostic performance of CCTA and to integrate the published data with our local experience. The 2 single-center published studies showed a significant improvement of image quality and coronary interpretability in per-segment and per-artery analysis with MC reconstruction. In the study of Fuchs, these data were obtained using low radiation dose. The study of Leipsic also showed an improvement of diagnostic accuracy. Our experience is consistent with the literature data, demonstrating better coronary evaluability in high HR patients. The multicenter trial ViCTORY will determine if MC algorithm will allow a routine improvement of CCTA diagnostic performance.     

The feasibility of sub-millisievert coronary CT angiography with low tube voltage,prospective ECG gating,and a knowledge-based iterative model reconstruction algorithm

We evaluated the feasibility of sub-millisievert (mSv) coronary CT angiography (CCTA) using low tube voltage, prospective ECG gating, and a knowledge-based iterative model reconstruction algorithm. Twenty-four non-obese healthy subjects (M:F 13:11; mean age 50.2 ± 7.8 years) were enrolled. Three sets of CT images were reconstructed using three different reconstruction methods: filtered back projection (FBP), iterative reconstruction (IR), and knowledge-based iterative model reconstruction (IMR). The scanning parameters were as follows: step-and-shoot axial scanning, 80 kVp, and 200 mAs. On the three sets of CT images, the attenuation and image noise values were measured at the aortic root. The signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) were calculated at the proximal right coronary artery and the left main coronary artery. The qualitative image quality of the CCTA with IMR was assessed using a 4-point grading scale (grade 1, poor; grade 4, excellent). The mean radiation dose of the CCTA was 0.89 ± 0.09 mSv. The attenuation values with IMR were not different from those of other reconstruction methods. The image noise with IMR was significantly lower than with IR and FBP. Compared to FBP, the noise reduction rate of IMR was 69 %. The SNR and CNR of CCTA with IMR were significantly higher than with FBP or IR. On the qualitative analysis with IMR, all included segments were diagnostic (grades 2, 3, and 4), and the mean image quality score was 3.6 ± 0.6. In conclusion, CCTA with low tube voltage, prospective ECG gating, and an IMR algorithm might be a feasible method that allows for sub-millisievert radiation doses and good image quality when used with non-obese subjects.     

Prospective ECG-triggered sequential scan protocol for coronary dual-source CT angiography: initial experience

The exposure to ionizing radiation has raised concerns about coronary CT angiography (CCTA). Recently, prospective ECG-triggered sequential scan technique has been introduced in CCTA to significantly reduce radiation exposure. The purpose of this study was to analyze our experience with the sequential scan technique on a dual-source CT system with respect to image quality and radiation dose. Qualitative and quantitative image quality as well as radiation dose were assessed in 514 consecutive patients undergoing CCTA either with sequential or spiral image acquisition technique on dual-source CT. The selection of the applied scan technique was at the discretion of an experienced coronary CT angiographer. A multivariate logistic regression analysis was applied to identify predictors of diagnostic image quality. Diagnostic CCTA image quality was found in 1,395/1,429 (97.6%) versus 4,664/4,782 (97.5%) of the coronary segments in patients studied with sequential versus spiral scanning (P = 0.82). While the application of betablockers for CCTA was an independent factor for improved image quality in the multivariate regression analysis, heart rate variability and body mass index were indepentently associated with a deterioriated image quality. The scan technique had no independent impact on diagnostic image quality. Mean estimated radiation dose was reduced by 63% in patients studied with sequential scan technique (3.4 ± 2.2 vs. 7.6 ± 5.0 mSv, P < 0.01). In patients with a low and stable heart rate, the sequential scan technique is a promising method to effectively reduce radiation exposure in dual-source CCTA. Due to the comparable image quality in sequential and spiral dual-source CCTA, the sequential scan technique should be considered as the primary scan protocol in appropriate patients.     

Assessment of image quality and radiation dose in prospective ECG-triggered coronary CT angiography compared with retrospective ECG-gated coronary CT angiography

We sought to determine the cut-off point of the average heart rate (HR) and HR differences in obtaining diagnostic image quality using prospective electrocardiographically-triggered (PT) coronary computed tomographic angiography (CCTA) and to compare image quality and radiation dose for CCTA obtained with PT CCTA and retrospective electrocardiographically-gated (RG) CCTA. A total of 178 patients who were referred for CCTA were enrolled in the study. Two independent radiologists evaluated subjective image quality. The non-diagnostic coronary segments were 32 of 1,226 segments (2.6%) for PT CCTA and 12 of 1,346 segments (0.9%) for RG CCTA (P < 0.001). The mean image quality scores for PT CCTA and RG CCTA were 3.82 ± 0.29 and 3.93 ± 0.14, respectively. The mean radiation dose of patients that underwent PT CCTA was 3.83 ± 0.84 mSv and RG CCTA 10.7 ± 2.70 mSv. For patients who underwent PT CCTA, image quality was inversely related to HR (56.5 ± 4.3 bpm; r = 0.38; P < 0.001) and HR differences (2.8 ± 2.7 bpm; r = 0.49; P < 0.001). With the use of receiver operator characteristic analysis, a cut-off HR of 57 bpm (58% sensitivity, 67% specificity) and HR difference of 6 bpm (93% sensitivity, 46% specificity) were the best threshold for the prediction of diagnostic image quality. In patients with a regular, low HR, PT CCTA offers diagnostic image quality and substantially reduces effective radiation compared with the use of RG CCTA with dose modulation.     

Prospective ECG-triggered sequential scan protocol for coronary dual-source CT angiography: initial experience

The exposure to ionizing radiation has raised concerns about coronary CT angiography (CCTA). Recently, prospective ECG-triggered sequential scan technique has been introduced in CCTA to significantly reduce radiation exposure. The purpose of this study was to analyze our experience with the sequential scan technique on a dual-source CT system with respect to image quality and radiation dose. Qualitative and quantitative image quality as well as radiation dose were assessed in 514 consecutive patients undergoing CCTA either with sequential or spiral image acquisition technique on dual-source CT. The selection of the applied scan technique was at the discretion of an experienced coronary CT angiographer. A multivariate logistic regression analysis was applied to identify predictors of diagnostic image quality. Diagnostic CCTA image quality was found in 1,395/1,429 (97.6%) versus 4,664/4,782 (97.5%) of the coronary segments in patients studied with sequential versus spiral scanning (P = 0.82). While the application of betablockers for CCTA was an independent factor for improved image quality in the multivariate regression analysis, heart rate variability and body mass index were indepentently associated with a deterioriated image quality. The scan technique had no independent impact on diagnostic image quality. Mean estimated radiation dose was reduced by 63% in patients studied with sequential scan technique (3.4 ± 2.2 vs. 7.6 ± 5.0 mSv, P < 0.01). In patients with a low and stable heart rate, the sequential scan technique is a promising method to effectively reduce radiation exposure in dual-source CCTA. Due to the comparable image quality in sequential and spiral dual-source CCTA, the sequential scan technique should be considered as the primary scan protocol in appropriate patients.     

Impact of PVCs noted during coronary calcium scan on image quality and accuracy in subsequent coronary dual-source CT angiography

The purpose of this study was to investigate the impact of the presence of one or more premature ventricular contractions (PVCs) during coronary calcium score scan (CS) on image quality and accuracy of subsequent dual-source coronary CT angiography (DS CCTA). Fifty-three out of 502 patients showed one or more PVCs during CS and built the study group. Sixty consecutively registered patients with sinus rhythm formed the control group. Two independent, blinded readers classified 1,723 coronary artery segments as being of diagnostic or non-diagnostic image quality. All segments with diagnostic image quality were assessed for the presence for significant coronary artery stenosis. Accuracy was calculated using conventional angiography as standard of reference. The percentage of DS CCTA data sets with diagnostic image quality was significantly lower in the study group (79.2%) compared to the control group (90.6%, P < 0.05). The rate of coronary segment with diagnostic image quality was highly significant lower in the study group (89.5%; n = 723/808) compared to the control group (99.4%; n = 908/915; P < 0.001). However, accuracy did not differ in both groups. Significant correlation between non-diagnostic image quality and mean HR was only found in the study group (P = 0.019). The presence of one or more PVCs during CS does not affect accuracy but impairs image quality of subsequent DS CCTA. Mean HR is a predictor of non-diagnostic data sets only in the study group, suggesting more aggressive HR control could be beneficial.     

Computer-aided simple triage (CAST) for coronary CT angiography (CCTA)

Purpose

Following a recent introduction of computer-aided simple triage (CAST) as a new subclass of computer-aided detection/diagnosis (CAD), we present a CAST software system for a fully automatic initial interpretation of coronary CT angiography (CCTA). We show how the system design and diagnostic performance make it CAST-compliant and suitable for chest pain patient triage in emergency room (ER).

Methods

The processing performed by the system consists of three major steps: segmentation of coronary artery tree, labeling of major coronary arteries, and detection of significant stenotic lesions (causing >?50% stenosis). In addition, the system performs an automatic image quality assessment to discards low-quality studies. For multiphase studies, the system automatically chooses the best phase for each coronary artery. Clinical evaluation results were collected in 14 independent trials that included more than 2000 CCTA studies. Automatic diagnosis results were compared with human interpretation of the CCTA and to cath lab results.

Results

The presented system performs a fully automatic initial interpretation of CCTA without any human interaction and detects studies with significant coronary artery disease. The system demonstrated higher than 90% per patient sensitivity and 40?C70% per patient specificity. For the chest pain, ER population, the specificity was 60?C70%, yielding higher than 98% NPV.

Conclusions

The diagnostic performance of the presented CCTA CAD system meets the CAST requirements, thus enabling efficient, 24/7 utilization of CCTA for chest pain patient triage in ER. This is the first fully operational, clinically validated, CAST-compliant CAD system for a fully automatic analysis of CCTA and detection of significant stenosis.     

CT-based myocardial ischemia evaluation: quantitative angiography,transluminal attenuation gradient,myocardial perfusion,and CT-derived fractional flow reserve

The detection of hemodynamically significant stenosis is important because ischemia-guided revascularization improves overall patient outcomes. Fractional flow reserve (FFR), which is measured during invasive coronary angiography, is regarded as the gold standard for determining hemodynamically significant coronary stenosis. Although coronary computed tomography angiography (CCTA) has been widely used to exclude significant coronary artery disease in patients with low to intermediate pretest probability, anatomic assessment by CCTA using diameter stenosis ≥50 % does not correlate well with the functional assessment of FFR. To overcome the weaknesses of conventional CCTA, such as its low specificity and positive predictive value, especially in patients with a small-diameter artery, poor image quality, or high calcium score, more sophisticated CCTA analysis methods have been developed to detect hemodynamically significant coronary stenosis. Studies that use the quantification of coronary plaque, transluminal attenuation gradient (TAG), CT myocardial perfusion (CTP), and CT-derived FFR have been conducted to validate their diagnostic performances, though each method has its pros and cons. This review provides details on the quantification of coronary plaque, TAG, CTP, and CT-derived FFR, including a definition of each, how to gather and interpret data, and the strengths and limitations of each. Further, we provide an overview of recent clinical studies.     

Subtraction coronary CT angiography using second-generation 320-detector row CT

The purpose of this study was to explore the feasibility of subtraction coronary computed tomography angiography (CCTA) by second-generation 320-detector row CT in patients with severe coronary artery calcification using invasive coronary angiography (ICA) as the gold standard. This study was approved by the institutional board, and all subjects provided written consent. Twenty patients with calcium scores of >400 underwent conventional CCTA and subtraction CCTA followed by ICA. A total of 82 segments were evaluated for image quality using a 4-point scale and the presence of significant (>50 %) luminal stenosis by two independent readers. The average image quality was 2.3 ± 0.8 with conventional CCTA and 3.2 ± 0.6 with subtraction CCTA (P < 0.001). The percentage of segments with non-diagnostic image quality was 43.9 % on conventional CCTA versus 8.5 % on subtraction CCTA (P = 0.004). The segment-based diagnostic accuracy for detecting significant stenosis according to ICA revealed an area under the receiver operating characteristics curve of 0.824 (95 % confidence interval [CI], 0.750–0.899) for conventional CCTA and 0.936 (95 % CI 0.889–0.936) for subtraction CCTA (P = 0.001). The sensitivity, specificity, positive predictive value, and negative predictive value for conventional CCTA were 88.2, 62.5, 62.5, and 88.2 %, respectively, and for subtraction CCTA they were 94.1, 85.4, 82.1, and 95.3 %, respectively. As compared to conventional, subtraction CCTA using a second-generation 320-detector row CT showed improvement in diagnostic accuracy at segment base analysis in patients with severe calcifications.     

Iterative reconstruction for coronary CT angiography: finding its way

Image reconstruction algorithms play a critical role in defining the quality and integrity of medical imaging using computed tomography. Since the advent of CT, image reconstruction has largely been performed by filtered back projection (FBP). This reconstruction technique has served CT well particularly at a time when there were significant limitations in computer processing capabilities. Iterative image reconstruction algorithms were, in fact available and were used to generate images with the very first commercial clinical computed tomographic (CT) scanner. This technique did not see significant adoption in clinical CT use owing to the ease of implementation and the faster image reconstruction of filtered back projection. Over the past decade, the need for finer resolution, greater volume coverage, faster scan times and the desire to lower radiation dose at the same time have pushed the performance of FBP reconstruction to its limits. Recently, there has been a re-introduction of iterative reconstruction for CT imaging with recently published studies in other organ systems showing that iterative reconstructions can produce higher-resolution images with greater robustness for the reduction of various imaging artifacts. There has been subsequent early adoption and experience with iterative reconstruction in coronary CT angiography (CCTA). We herein review the various iterative reconstruction platforms released for use for CCTA and the initial experiences implementing and integrating these reconstruction algorithms in clinical practice.     

心率、扇区重组、时相重建对64层螺旋CT冠状动脉成像质量的影响

目的探讨心率、重组方法和重建时相窗对64层螺旋CT冠状动脉成像质量的影响。方法398例64层螺旋CT冠状动脉造影扫描,根据不同心率应用不同扇区重组、多相位重建,传入后处理工作站进行图像重建。结果心率在50-70次/分所得冠状动脉图像质量较好,但扫描时心律变化幅度大者成像质量下降。心率〉75次/分,用双扇区和四扇区重组能获得相对高质量的图像。左前降支、回旋支在75%R-R时相重建图像较好,右冠状动脉在45%R-R时相显示较好。结论64层螺旋CT冠状动脉成像质量与心率、扇区重组的应用和多相位重建密切相关。     

320-row CT coronary angiography: effect of 100-kV tube voltages on image quality,contrast volume,and radiation dose

To prospectively evaluate image quality parameters, contrast volume and radiation dose at the 100-kilovolt (kV) setting during coronary computed tomographic angiography (CCTA) on a 320-row computed tomography scanner. We enrolled 107 consecutive patients with a heart rate <65 beats per minute (bpm) undergoing prospective electrocardiogram (ECG)-triggered CCTA. Forty patients with a body mass index (BMI) <25 kg/m² were scanned using 100-kV tube voltage settings, while 67 patients were scanned using 120-kV protocols. Image quality was assessed by two readers unaware of patient information and scan parameters. Attenuation in the aorta and perivascular fat tissue and image noise were measured. Contrast-to-noise ratios (CNRs) and contrast material volumes were calculated. The effective radiation doses were estimated using a chest conversion coefficient (0.017). Diagnostic image quality was achieved in 98.2% of coronary segments with 100-kV CCTA and 98.6% of coronary segments with 120-kV CCTA, with no significant differences in image quality scores for each coronary segment. Vessel attenuation, image noise, and CNR were not significantly different between the 100- and 120-kV protocols. Mean contrast injection rate and mean material volume were significantly lower for the 100-kV CCTA (4.35 ± 0.28 ml/s and 53.13 ± 3.77 ml, respectively) than for the 120-kV CCTA (5.16 ± 0.21 ml/s and 62.40 ± 3.66 ml respectively; P < 0.001). The effective radiation dose was 2.12 ± 0.19 mSv for 100-kV CCTA, a reduction of 54% compared to 4.61 ± 0.82 mSv for 120-kV CCTA. A 100-kV CCTA can be implemented in patients with a BMI < 25 kg/m². The 100-kV setting allows significant reductions in contrast material volume and effective radiation dose while maintaining adequate diagnostic image quality.     

Cardiac CT for acute chest pain in the emergency department: advantages of prospective triggering

Coronary CT angiography (CCTA) is emerging as a powerful tool for the diagnosis and characterization of coronary artery disease. In the emergency department (ED) setting, the high negative predictive value of CCTA has been shown to reduce the length of stay and the cost of care in the evaluation of patients at low and intermediate risk for an acute coronary syndrome (ACS). In addition, CCTA and triple-rule-out protocol CT examinations which simultaneously evaluate the coronary arteries, aorta and pulmonary arteries, have the potential to diagnose not only significant atherosclerotic coronary artery disease (CAD) and coronary artery anomalies, but noncoronary etiologies of chest pain, including pulmonary embolism, aortic dissection, infection, pleural and pericardial disease. Caution has been raised about the widespread use of CCTA in this setting, particularly given the prevalence of repeat ED visits for chest pain, due to the radiation exposure associated with retrospectively-gated CCTA. However, the recent development of prospectively-triggered coronary artery CTA makes the ED evaluation possible with a substantially lower radiation exposure to the patient. Although most studies of CCTA to date are performed with retrospective ECG gating, early reports on prospectively triggered CCTA demonstrate equivalent image quality and accuracy when compared to studies acquired with retrospective ECG gating.     

Cardiac CT for acute chest pain in the emergency department: advantages of prospective triggering

Coronary CT angiography (CCTA) is emerging as a powerful tool for the diagnosis and characterization of coronary artery disease. In the emergency department (ED) setting, the high negative predictive value of CCTA has been shown to reduce the length of stay and the cost of care in the evaluation of patients at low and intermediate risk for an acute coronary syndrome (ACS). In addition, CCTA and triple-rule-out protocol CT examinations which simultaneously evaluate the coronary arteries, aorta and pulmonary arteries, have the potential to diagnose not only significant atherosclerotic coronary artery disease (CAD) and coronary artery anomalies, but noncoronary etiologies of chest pain, including pulmonary embolism, aortic dissection, infection, pleural and pericardial disease. Caution has been raised about the widespread use of CCTA in this setting, particularly given the prevalence of repeat ED visits for chest pain, due to the radiation exposure associated with retrospectively-gated CCTA. However, the recent development of prospectively-triggered coronary artery CTA makes the ED evaluation possible with a substantially lower radiation exposure to the patient. Although most studies of CCTA to date are performed with retrospective ECG gating, early reports on prospectively triggered CCTA demonstrate equivalent image quality and accuracy when compared to studies acquired with retrospective ECG gating.     

Image quality in low-dose coronary computed tomography angiography with a new high-definition CT scanner

A new generation of high definition computed tomography (HDCT) 64-slice devices complemented by a new iterative image reconstruction algorithm—adaptive statistical iterative reconstruction, offer substantially higher resolution compared to standard definition CT (SDCT) scanners. As high resolution confers higher noise we have compared image quality and radiation dose of coronary computed tomography angiography (CCTA) from HDCT versus SDCT. Consecutive patients (n = 93) underwent HDCT, and were compared to 93 patients who had previously undergone CCTA with SDCT matched for heart rate (HR), HR variability and body mass index (BMI). Tube voltage and current were adapted to the patient’s BMI, using identical protocols in both groups. The image quality of all CCTA scans was evaluated by two independent readers in all coronary segments using a 4-point scale (1, excellent image quality; 2, blurring of the vessel wall; 3, image with artefacts but evaluative; 4, non-evaluative). Effective radiation dose was calculated from DLP multiplied by a conversion factor (0.014 mSv/mGy × cm). The mean image quality score from HDCT versus SDCT was comparable (2.02 ± 0.68 vs. 2.00 ± 0.76). Mean effective radiation dose did not significantly differ between HDCT (1.7 ± 0.6 mSv, range 1.0–3.7 mSv) and SDCT (1.9 ± 0.8 mSv, range 0.8–5.5 mSv; P = n.s.). HDCT scanners allow low-dose 64-slice CCTA scanning with higher resolution than SDCT but maintained image quality and equally low radiation dose. Whether this will translate into higher accuracy of HDCT for CAD detection remains to be evaluated.     

新双源CT冠状动脉CTA不同扫描参数与重建算法获得图像质量的体模研究

目的 探讨基于原始数据域的迭代重建(SAFIRE)算法与滤波反投影(FBP)算法冠状动脉CT血管造影(CCTA)图像质量的差异。方法 对置入模拟左、右冠状动脉的仿真体模,采用两组管电压(100 kV、120 kV)行双源CT检查,对冠状动脉原始图像在工作站上分别进行FBP及SAFIRE两种算法的图像重建,对不同管电压及不同管电流组内图像质量指标SNR、CNR、CT值标准差进行t检验;相同管电压不同重建算法,不同管电压相同管电流SAFIRE重建方式的两组SNR、CNR、CT值标准差及CT值采用配对t检验。结果 两组管电压扫描后经SAFIRE重建的冠状动脉图像质量均明显优于FBP重建;两组管电压两种重建算法图像,随着管电流的增加,200~360 mA图像质量呈改善趋势,管电流340 mA及以上图像质量指标趋于稳定;不同管电压相同管电流SAFIRE重建算法成像其图像质量比较,CNR、SNR、CT值标准差差异均有统计学意义(t=5.36、2.49、21.82,P均<0.05)。结论 随着扫描参数(管电流与管电压)的增加,图像质量随之上升,但到达一定值后图像质量趋于稳定;采用SAFIRE在相同扫描条件下可以明显提高图像质量。     

Economic Considerations for Coronary CT Angiography

In recent years, coronary CT angiography (CCTA) has emerged has a noninvasive anatomic imaging modality that demonstrates high diagnostic performance to detect and exclude high-grade coronary artery stenosis. Proponents of CCTA have advocated its use as an effective alternative to functional stress imaging, while critics have maintained that the benefits of CCTA use remain unproven and may promote unnecessary “layering” of imaging studies on top of conventional stress testing. In this review, we consider the clinical and economic data related to CCTA to date, and suggest future studies that may clarify the role of CCTA in daily clinical evaluation of patients with suspected or known coronary artery disease.     

Improved evaluation of calcified segments on coronary CT angiography: a feasibility study of coronary calcium subtraction

We explore the feasibility of coronary calcium subtraction computed tomography angiography (CCTA) in patients with high calcium scores using invasive coronary angiography as the gold standard. Eleven patients with calcium scores of >400 underwent CCTA using a subtraction protocol followed by invasive coronary angiography. In addition to standard reconstructions, subtracted images were obtained using a dedicated subtraction algorithm. A total of 55 calcified segments were evaluated for image quality [using a 4-point scale ranging from 1 (uninterpretable) to 4 (good)] and the presence of significant (≥50 %) luminal stenosis. Conventional and subtracted CCTA were compared using quantitative coronary angiography (QCA) as the gold standard. The average image quality of conventional CCTA was 2.5 ± 0.6 versus 3.1 ± 0.6 on subtraction CCTA (P < 0.001). The percentage of segments with a score 1 or 2 was reduced from 41.8 to 12.7 % after coronary calcium subtraction (P = 0.002). On QCA, significant stenosis was observed in 16 segments. The area under the receiver operating characteristics curve to detect ≥50 % stenosis on QCA increased from 0.741 [95 % confidence interval (CI) 0.598–0.885] for conventional CCTA to 0.905 (95 % CI 0.791–1.000) for subtraction CCTA (P = 0.003). In patients with extensive calcifications undergoing CCTA, coronary calcium subtraction may improve the evaluation of calcified segments.     

Helical prospective ECG-gating in cardiac computed tomography: radiation dose and image quality

Helical prospective ECG-gating (pECG) may reduce radiation dose while maintaining the advantages of helical image acquisition for coronary computed tomography angiography (CCTA). Aim of this study was to evaluate helical pECG–gating in CCTA in regards to radiation dose and image quality. 86 patients undergoing 64-multislice CCTA were enrolled. pECG-gating was performed in patients with regular heart rates (HR) < 65 bpm; with the gating window set at 70–85% of the cardiac cycle. All patients received oral and some received additional IV beta-blockers to achieve HR < 65 bpm. In patients with higher or irregular HR, or for functional evaluation, retrospective ECG-gating (rECG) was performed. The average X-ray dose was estimated from the dose length product. Each arterial segment (modified AHA/ACC 17-segment-model) was evaluated on a 4-point image quality scale (4 = excellent; 3 = good, mild artefact; 2 = acceptable, some artefact, 1 = uninterpretable). pECG-gating was applied in 57 patients, rECG-gating in 29 patients. There was no difference in age, gender, body mass index, scan length or tube output settings between both groups. HR in the pECG-group was 54.7 bpm (range, 43–64). The effective radiation dose was significantly lower for patients scanned with pECG-gating with mean 6.9 mSv ± 1.9 (range, 2.9–10.7) compared to rECG with 16.9 mSv ± 4.1 (P < 0.001), resulting in a mean dose reduction of 59.2%. For pECG-gating, out of 969 coronary segments, 99.3% were interpretable. Image quality was excellent in 90.2%, good in 7.8%, acceptable in 1.3% and non-interpretable in 0.7% (n = 7 segments). For patients with steady heart rates <65 bpm, helical prospective ECG-gating can significantly lower the radiation dose while maintaining high image quality.     

Coronary Computed Tomography Angiography: Costs and Current Reimbursement Status

Coronary computed tomography angiography (CCTA) has evolved as the most sensitive diagnostic non-invasive test for diagnosing coronary artery disease (CAD). Outcomes data is accumulating and demonstrating that CCTA has excellent prognostic value. Given CCTA’s consistently proven accuracy and improved safety related to radiation sparing techniques, public health officials have called for comparative cost-effectiveness research of CCTA vs other diagnostic testing strategies for assessing possible angina in symptomatic patients. In this article, we review the available cost studies of CCTA in comparison with other diagnostic strategies. Currently available data are limited but include 5 completed randomized trials, 11 observational studies, 7 studies using theoretical mathematical modeling, and 4 reports of the cost impact of incidental findings on CCTA. Additional randomized trials including cost considerations are ongoing, but evidence from available randomized, observational, and theoretical modeling data mostly support CCTA as a potentially cost-saving, non-invasive test for the evaluation of CAD in symptomatic patients.