Systolic prospectively ECG-triggered dual-source CT angiography for evaluation of the coronary arteries in heart transplant recipients

Objectives  

To assess feasibility, image quality, and radiation dose of prospectively ECG-triggered coronary CT angiography (CTA) in orthotopic heart transplant (OHT) recipients.     

收缩期前瞻性心电门控双源CT血管成像评价心脏移植受者的冠状动脉

目的评价心脏原位移植受者前瞻性心电门控冠状动脉CT血管成像的可行性、影像质量和辐射剂量。方法连续选取47例心脏原位移植受者[男40例,平均年龄(62.1±10.9)岁,平均心率(86.3±14.4)次/min]进行心动周期为35%～     

Age-related differences in image quality of prospectively ECG-triggered axial and helical scans for coronary CT angiography

We investigated the underlying reasons for the occurrence of misalignment artifacts in prospectively ECG-triggered axial coronary CT angiography scans. In this study we analyzed 56 consecutive patients scanned in axial mode and 66 consecutive patients scanned in helical mode. Predictors for the occurrence of misalignment artifacts were evaluated by multivariable logistic regression analysis for those patients scanned in the axial mode; advanced age was identified as the sole independent predictor (odds ratio: 1.088; 95 % CI: 1.012–1.170; p = 0.0228). In a comparison with the patients scanned in the helical mode, the image quality score for patients aged 65 years or older was significantly higher in helical mode than in axial mode (2.6 ± 0.5 and 2.4 ± 0.7, respectively; p = 0.0313). Misalignment artifacts in the image are more common in the elderly than in younger. Helical mode should be preferred in this older patient population to allow for good diagnostic image quality.     

低剂量前瞻性心电触发序列扫描在房颤患者冠状动脉CT成像的研究

目的 研究前瞻性心电触发序列扫描在房颤患者冠状动脉CT成像的可行性.方法 前瞻性连续入组94例持续房颤患者,47例患者采用前瞻性心电门控序列扫描,另外47例采用回顾性心电门控螺旋扫描.设备采用第二代双源CT.以冠状动脉段为基础评价图像质量,比较两组的图像质量和辐射剂量.结果 前瞻组可诊断的血管段为99.5％（604/607）,回顾组为97.7％（570/584）,前瞻组显著高于回顾组（P＜0.001）.以患者为基础,前瞻组43例（92％）为可诊断,回顾组29例（62％）为可诊断病例.有效辐射剂量在前瞻和回顾组分别为（4.15±1.78）mSv和（12.15±5.38）mSv,两组之间差异有显著性（P＜0.001）.序列扫描降低辐射剂量66 ％.结论 采用第二代双源CT,前瞻性心电触发序列扫描对于房颤患者冠状动脉CT成像具有可行性,该扫描方案可以显著降低辐射剂量,并保证诊断所需图像质量.     

第二代双源CT前门控FLASH扫描与序列扫描冠状动脉成像比较

目的:比较第二代双源CT前门控大螺距螺旋扫描(FLASH扫描)与序列扫描模式在冠状动脉CT成像中的图像质量及辐射剂量。方法:回顾性分析采用第二代双源CT行前门控FIASH扫描(A组)与序列扫描(B组)冠状动脉CTA连续各50例患者,入组标准为心率70次/min以下,窦性心律,心率波动范围在10次/min以内。评价这2种成像模式的图像质量及辐射剂量。扫描参数:2组均采用Z轴飞焦点技术采集,探测器准直宽度0.6 mm,重建层厚0.75 mm,扫描时间0.28 s/r,单扇区时间分辨率75 ms,根据患者体质量指数(BMI)值设定管电压:100kV(BMI<24 kg/m~2)、120 kV(BMI≥24 kg/m~2),参考管电流370 mAs,采用管电流调制方案;FLASH扫描前门控心电触发选在60%R-R间期,螺距3.4;序列扫描采集时相为35%～75%R-R间期,步进采集宽度34.5 mm。冠状动脉图像质量分为4级(1级为优异,1～3级为可评价血管,4级为不可评价血管),相应评为1～4分。应用秩和检验比较2组患者冠状动脉段图像质量评分,应用两独立样本t检验比较2组患者所接受的辐射剂量。结果:A、B 2组患者的年龄及BMI差异无统计学意义。A、B 2组可评价的冠状动脉节段百分比分别为98.21%和98.56%,差异无统计学意义(χ~2=0.244,P=0.621),平均图像质量评分分别为1.30±0.60和1.28±0.56,差异无统计学意义(Z=-0.489,P=0.625)。A、B 2组扫描的平均有效辐射剂量分别为(0.99±0.34)mSv和(4.80±2.21)mSv,差异有统计学意义(t=-12.048,P=0.000),FLASH扫描剂量明显低于序列扫描。结论:在心率低于70次/min、心律稳定的情况下,第二代双源CT前门控FLASH扫描可获得与序列扫描相似的高质量图像,但辐射剂量明显降低。     

Evaluation of coronary artery in-stent restenosis with prospectively ECG-triggered axial CT angiography versus retrospective technique: a phantom study

Purpose

This study compared the performance of prospectively electrocardiographically (ECG)-triggered axial computed tomography (CT) angiography with retrospective technique in evaluating coronary artery stent restenosis by 64-slice CT.

Materials and methods

A pulsing cardiac phantom with artificial coronary artery in-stent restenosis was examined by CT angiography with different types of scan modes. The visibility of in-stent restenosis was evaluated with a three-point score. Artificial lumen narrowing [(inner stent diameter-measured lumen diameter)/inner stent diameter], lumen attenuation increase ratio [(in-stent attenuation-coronary artery lumen attenuation)/coronary artery lumen attenuation], measurement error of restenosis percent [(known restenosis percent-measured restenosis percent)/known restenosis percent] and imaging noise were analysed.

Results

Prospective acquisition showed better visibility than retrospective acquisition (p<0.05): 61% of in-stent restenoses had good visibility on the prospective acquisition compared with 17% on the retrospective acquisition. Furthermore, the effective dose was 6.2±0.3 mSv for the prospective technique compared with 18.8±1.1 mSv for the retrospective technique. Artificial lumen narrowing (mean 40%), lumen attenuation increase ratio (mean 33%) and measurement error of restenosis percent were not different between types of CT acquisitions.

Conclusions

Compared with the traditional retrospective technique, prospective coronary CT angiography offers improved image quality and reduces effective radiation dose in evaluating in-stent restenosis.     

Detection of coronary artery stenosis with sub-milliSievert radiation dose by prospectively ECG-triggered high-pitch spiral CT angiography and iterative reconstruction

Objectives

To evaluate the diagnostic accuracy of sub-milliSievert (mSv) coronary CT angiography (cCTA) using prospectively ECG-triggered high-pitch spiral CT acquisition combined with iterative image reconstruction.

Methods

Forty consecutive patients (52.9?±?8.7 years; 30 men) underwent dual-source cCTA using prospectively ECG-triggered high-pitch spiral acquisition. The tube current-time product was set to 50 % of standard-of-care CT examinations. Images were reconstructed with sinogram-affirmed iterative reconstruction. Image quality was scored and diagnostic performance for detection of ≥50 % stenosis was determined with catheter coronary angiography (CCA) as the reference standard.

Results

CT was successfully performed in all 40 patients. Of the 601 assessable coronary segments, 543 (90.3 %) had diagnostic image quality. Per-patient sensitivity for detection of ≥50 % stenosis was 95.7 % [95 % confidence interval (CI), 76.0-99.8 %] and specificity was 94.1 % (95 % CI, 69.2-99.7 %). Per-vessel sensitivity was 89.5 % (95 % CI, 77.8-95.6 %) with 93.2 % specificity (95 % CI, 86.0-97.0 %). The area under the receiver-operating characteristic curve on per-patient and per-vessel levels was 0.949 and 0.913. Mean effective dose was 0.58?±?0.17 mSv. Mean size-specific dose estimate was 3.14?±?1.15 mGy.

Conclusions

High-pitch prospectively ECG-triggered cCTA combined with iterative image reconstruction provides high diagnostic accuracy with a radiation dose below 1 mSv for detection of coronary artery stenosis.

Key Points

? Cardiac CT with sub-milliSievert radiation dose is feasible in many patients ? High-pitch spiral CT acquisition with iterative reconstruction detects coronary stenosis accurately. ? Iterative reconstruction increases who can benefit from low-radiation cardiac CT.     

前瞻性心电触发扫描模式应用于心律不齐患者冠状动脉CTA检查的可行性研究

目的：探讨心律不齐患者采用前瞻性心电触发扫描模式行冠状动脉CTA检查的可行性。方法：回顾性搜集本院行冠状动脉CTA检查的13例心律不齐患者的病例资料。所有患者均行双源CT扫描结合前瞻性心电触发扫描模式,每个R波后250～350ms采集,管电压120kVp,自动毫安。对比剂采用碘克沙醇（270mgI／mL）,注射30mL。记录所有患者的辐射剂量。将冠状动脉分为15个节段,由2名影像科医师进行图像质量评价,并测量cT值。对结果进行统计学分析。结果：13例患者均一次完成检查,平均有效辐射剂量为（2．61±1．29）mGy。主观评估了冠状动脉CTA的172个节段,有163个节段达到诊断要求,94．77％满足临床诊断要求。80．12％的节段管腔内CT值〉250HU。结论：心律不齐患者应用前瞻性心电触发扫描模式时,行冠状动脉cTA检查可以得到较好的图像质量,基本满足临床诊断要求。     

第二代双源CT前门控冠状动脉成像与冠状动脉造影比较的初步研究

目的:探讨第二代双源CT前门控冠状动脉成像(CTCA)对冠状动脉狭窄病变的诊断价值。方法:连续44例同期行第二代双源CT前门控CTCA(其中前门控序列扫描35例,前门控大螺距螺旋扫描9例)及选择性冠状动脉造影(SCA)检查的患者,按冠脉病变狭窄程度分为:无狭窄;轻度狭窄(狭窄≤50%);中度狭窄(狭窄50%～75%);重度狭窄(狭窄≥75%);闭塞(狭窄100%),将中度及中度以上狭窄定义为有意义狭窄。以SCA为金标准,分析第二代双源CT前门控CTCA诊断冠状动脉狭窄的敏感性、特异性、阳性和阴性预测值及准确度,同时计算第二代双源CT前门控CTCA的辐射剂量。结果:44例患者冠脉直径2mm以上的节段共570个,其中12段图像质量较差,无法评估,可评估节段占97.89%。第二代双源CT前门控CTCA按冠脉节段计算,诊断冠状动脉狭窄的敏感度、特异度、阳性和阴性预测值、准确度分别为90.18%、93.05%、76.52%、97.42%、92.47%,诊断冠状动脉有意义狭窄的敏感度、特异度、阳性和阴性预测值、准确度分别为90.14%、95.69%、75.29%、98.52%、94.98%。第二代双源CT前门控CTCA与SCA比较对冠状动脉狭窄评价的差异无统计学意义(χ2=2.10,P>0.05),对冠状动脉有意义狭窄评价的差异无统计学意义(χ2=1.46,P>0.05)。第二代双源CT前门控CT-CA的平均辐射剂量为(3.36±1.59)mSv,其中前门控序列扫描的平均辐射剂量为(3.99±1.18)mSv,前门控大螺距螺旋扫描的平均辐射剂量为(1.11±0.44)mSv。结论:第二代双源CT前门控成像对诊断冠状动脉狭窄的准确度稍低于SCA,但其阴性预测值较高,同时其辐射剂量较低,可作为临床冠心病筛查的无创性检查手段。     

Noninvasive coronary angiography with 16-detector row CT: effect of heart rate

PURPOSE: To evaluate the effect of heart rate on the quality of coronary angiograms obtained with 16-detector row computed tomography (CT) by using temporally enhanced three-dimensional (3D) approaches. MATERIALS AND METHODS: The local ethics committee approved the study, and informed consent was obtained from all patients. Fifty patients underwent coronary CT angiography (heart rate range, 45-103 beats per minute). Raw data from helical CT and electrocardiography (ECG) were saved in a combined data set. Retrospectively ECG-gated images were reconstructed at preselected phases (50% and 80%) of the cardiac cycle. A 3D voxel-based approach with cardiac phase weighting was used for reconstruction. Testing for correlation between heart rate, cardiac phase reconstruction window, and image quality was performed with Kruskal-Wallis analysis. Image quality (freedom from cardiac motion-related artifacts) was referenced against findings at conventional angiography in a secondary evaluation step. Regression analysis was performed to calculate heart rate thresholds for future beta-blocker application. RESULTS: A significant negative correlation was observed between heart rate and image quality (r = 0.80, P < .001). Motion artifact-free images were available for 44 (88%) patients and were achieved consistently at a heart rate of 80 or fewer beats per minute (n = 39). Best image quality was achieved at 75 or fewer beats per minute. Segmental analysis revealed that 97% of arterial segments (diameter > or = 1.5 mm according to conventional angiography) were assessable at 80 or fewer beats per minute. Premature ventricular contractions and rate-contained arrhythmia did not impede diagnostic assessment of the coronary arteries in 10 (83%) of the 12 patients affected. CONCLUSION: Motion-free coronary angiograms can be obtained consistently with 16-detector row CT scanners and adaptive multicyclic reconstruction algorithms in patients with heart rates of less than 80 beats per minute.     

Systolic reconstruction in patients with low heart rate using coronary dual-source CT angiography

Objectives

The purpose of our study was to determine the relationship between the predictive factors and systolic reconstruction (SR) as an optimal reconstruction window in patients with low heart rate (LHR; less than 65 bpm).

Methods

391 patients (262 male and 129 female, mean age; 67.1 ± 10.1 years of age) underwent coronary CTA without the additional administration of a beta-blocker. Affecting factors for SR were analyzed in age, gender, body weight (BW), diabetes mellitus (DM), coronary arterial disease (CAD), ejection fraction (EF), systolic and diastolic body pressure (BP) and heart rate variability (HRV) during coronary CTA.

Results

In 29 (7.4%) of the 391 patients, SR was needed, but there was no apparent characteristic difference between the systolic and diastolic reconstruction groups in terms of gender, age, BW, DM, CAD and EF. In a multivariate analysis, the co-existence of DM [P < 0.05; OR, 0.27; 95% CI, 0.092-0.80], diastolic BP [P < 0.01; OR, 0.95; 95% CI, 0.92-0.98] and HRV [P < 0.01; OR, 0.98; 95% CI, 0.96-0.99] were found to be the factors for SR. In gender-related analysis, HRV was an important factor regardless of sex, but co-existence of DM affected especially for female and BP for male.

Conclusion

Especially in the patients with LHR who had a medication of DM, high HRV or high BP, SR, in addition to DR, was needed to obtain high-quality coronary CTA images.     

第3代双源CT低剂量Turbo Flash成像图像质量与诊断效能的临床研究

目的探讨第3代双源CT大螺距前瞻性心电门控扫描模式(Turbo Flash)冠状动脉CT成像(CCTA)评价冠状动脉狭窄的准确性、图像质量及有效辐射剂量。方法前瞻性收集2016年4月至2017年4月接受第3代双源CCTA检查的患者1003例,其中有70例患者在CCTA检查后30 d内行冠状动脉造影(CAG)。对冠状动脉各节段图像质量进行评分,计算有效辐射剂量。以CAG结果为“金标准”,计算CCTA显示冠状动脉病变的灵敏度、特异度、阳性预测值和阴性预测值;CCTA与CAG评价冠状动脉狭窄分级的一致性采用Kappa值并进行U检验。结果(1) 图像质量：右冠状动脉不可诊断血管节段为0,左冠状动脉主干及前降支不可诊断血管节段为0,左冠状动脉回旋支不可诊断血管节段为0.04% (3/835)。(2)准确性评价：基于节段水平分析,Force CT诊断冠状动脉狭窄的灵敏度为97.0% (289/298)、特异度为98.3% (706/718)、阳性预测值为96.0% (289/301)、阴性预测值为98.7% (706/715);基于血管分析,灵敏度为97.5% (159/163)、特异度为85.1% (40/47)、阳性预测值为95.8% (159/166)、阴性预测值为90.9% (40/44);基于患者分析,灵敏度、特异度、阳性预测值、阴性预测值均为100%。CCTA与CAG显示的冠状动脉狭窄部位高度一致(U=2.4,P=0.008)。(3)辐射剂量：有效辐射剂量为(1.17±0.29)mSv。结论第3代双源CT Turbo Flash模式可以在自然呼吸、无心率干预下进行冠状动脉成像,扫描成功率高,图像质量佳,评价冠状动脉狭窄的准确性高,有效辐射剂量低。     

前瞻性心电门控MSCT冠状动脉成像研究进展

近年来CT硬件水平的提升使得冠状动脉CT血管成像得以广泛应用,而传统回顾性心电门控冠状动脉CTA的高辐射剂量一直是令人担忧的问题。前瞻性心电门控冠状动脉CTA在影像质量无差别的情况下可以大幅降低病人受线剂量,具有替代回顾性心电门控冠状动脉CTA的潜在价值。目前,前瞻性心电门控技术的研究主要针对影像质量及辐射剂量两方面进行。64层以上机型的投入使用将会对前瞻性心电门控技术产生深远的影响。     

Prospectively ECG-triggered sequential dual-source coronary CT angiography in patients with atrial fibrillation: comparison with retrospectively ECG-gated helical CT

Objective

To investigate the feasibility of applying prospectively ECG-triggered sequential coronary CT angiography (CCTA) to patients with atrial fibrillation (AF) and evaluate the image quality and radiation dose compared with a retrospectively ECG-gated helical protocol.

Methods

100 patients with persistent AF were enrolled. Fifty patients were randomly assigned to a prospective protocol and the other patients to a retrospective protocol using a second-generation dual-source CT (DS-CT). Image quality was evaluated using a four-point grading scale (1 = excellent, 2 = good, 3 = moderate, 4 = poor) by two reviewers on a per-segment basis. The coronary artery segments were considered non-diagnostic with a quality score of 4. The radiation dose was evaluated.

Results

Diagnostic segment rate in the prospective group was 99.4 % (642/646 segments), while that in the retrospective group was 96.5 % (604/626 segments) (P?<?0.001). Effective dose was 4.29?±?1.86 and 11.95?±?5.34 mSv for each of the two protocols (P?<?0.001), which was a 64 % reduction in the radiation dose for prospective sequential imaging compared with retrospective helical imaging.

Conclusion

In AF patients, prospectively ECG-triggered sequential CCTA is feasible using second-generation DS-CT and can decrease >60 % radiation exposure compared with retrospectively ECG-gated helical imaging while improving diagnostic image quality.

Key Points

? Coronary computed tomographic angiography (CCTA) can be difficult in patients with arrhythmias. ? Prospectively ECG-triggered sequential CCTA is feasible in patients with atrial fibrillation. ? Prospective sequential imaging can improve quality compared with retrospective analysis. ? Prospective sequential imaging decreases radiation exposure by 64 % compared with retrospective mode.     

Application of prospective ECG-triggered dual-source CT coronary angiography for infants and children with coronary artery aneurysms due to Kawasaki disease

Objectives

The aim of this study was to prospectively evaluate the initial application and value of prospective electrocardiogram (ECG)-triggered dual-source CT coronary angiography (DSCTCA) in the diagnosis of infants and children with coronary artery aneurysms due to Kawasaki disease.

Methods

19 children [12 males; mean age 13.47 months, range 3 months to 5 years; mean heart rate 112 beats per minute (bpm), range 83–141 bpm] underwent prospective ECG-triggered DSCTCA with free breathing. Subjective image quality was assessed on a five-point scale (1, excellent; 5, non-diagnostic) by two blinded observers. The location, number and size of each aneurysm were observed and compared with those of transthoracic echocardiography (TTE) performed within 1 week. Interobserver agreement concerning the subjective image quality was evaluated with Cohen''s κ-test. Bland–Altman analysis was used to evaluate the agreement on measurements (diameter and length of aneurysms) between DSCTCA and TTE. The average effective dose required for DSCTCA was calculated for all children.

Results

All interobserver agreement for subjective image quality assessment was excellent (κ=0.87). The mean±standard deviation (SD) aneurysm diameter with DSCTCA was 0.76±0.36 cm and with TTE was 0.76±0.39 cm. The mean±SD aneurysm length with DSCTCA was 2.06±1.35 cm and with TTE was 2.00±1.22 cm. The Bland–Altman plot for agreement between DSCTCA and TTE measurements showed good agreement. The mean effective dose was 0.36±0.06 mSv.

Conclusion

As an alternative diagnostic modality, prospective ECG-triggered DSCTCA with excellent image quality and low radiation exposure has been proved useful for diagnosing infants and children with coronary artery aneurysms due to Kawasaki disease.

Advances in knowledge

Prospective ECG–triggered DSCTCA for infants and children allows rapid, accurate assessment of coronary aneurysms due to Kawasaki diseases, compared with TTE.Kawasaki disease (KD), also known as mucocutaneous lymph node syndrome, is an autoimmune vasculitis in which the small and medium vessels throughout the body become inflamed [1,2]. It predominantly occurs in infants and children (younger than 5 years old). It affects many organ systems; injury, such as aneurysm, dilation, ectasia, stenosis and embolism, to the heart is rare but serious, and fatal myocardial infarction can be induced in untreated cases [3-6]. It is crucial to detect coronary artery lesions at an early stage [7]. Diagnosis of KD is based on clinical signs, symptoms and laboratory findings, but no specific laboratory test exists and it is hard to establish the diagnosis, especially in the early course [8].Recently, multidetector CT, especially the advent of dual-source CT, has provided improved spatial and temporal resolution; moreover, multiple techniques on dose reduction have been applied in children. Electrocardiogram (ECG)-gated scans, especially retrospective ECG-gated scans, have been used to evaluate coronary artery lesions in children with KD [2,9]. The high radiation dose required remains the main concern [10]; even though dose-saving methods including low tube potential, tube current modulation and body size-adapted CT protocols have been adopted, the effective radiation dose is still high at up to 2.17–3.14 mSv [11-13].Recently, prospective ECG-triggered scans were considered to be the most promising approach for dose reduction as they were used in the assessment of cardiovascular deformities in children with congenital heart disease [14-17]; however, no further studies have been reported on the application of prospective ECG-triggered CT angiography in children with KD.The aim of this study was to evaluate the initial application of prospective ECG-triggered dual-source CT coronary angiography (DSCTCA) in infants and children with coronary artery aneurysms due to KD.