大螺距双源CT心脏与头颈血管一站式联合扫描的可行性

目的 评价Flash双源CT前瞻性心电门控螺旋扫描模式（Flash Spiral模式）心脏与头颈血管一站式联合成像的图像质量、辐射剂量。方法 选择246例连续性患者,分为3组,每组82例：A组采用Flash Spiral模式行心脏与头颈血管联合扫描;B组采用Flash Spiral模式心脏成像;C组采用双能量扫描模式行头颈部CTA。分别测量主动脉根部CT值及CNR,测量颈总动脉起始部、颈内动脉起始部、大脑中动脉M1段、椎动脉V4段CT值及图像噪声,评价图像质量、有效辐射剂量。结果 A组与B组冠状动脉平均图像质量评分差异无统计学意义（P>0.05）,A组与C组头颈部血管图像质量评分差异无统计学意义（P>0.05）,A组头颈部ED显著低于C组（t=24.215,P<0.01）。结论 大螺距双源CT Flash Spiral模式心脏与头颈部血管一站式联合扫描图像质量好,成功率高,对比剂用量少,辐射剂量低。     

Prospective ECG-triggered sequential versus retrospective ECG-gated spiral CT: Pros and cons

Advancement of multidetector CT makes it possible to visualize the coronary arteries, as well as ventricular and valvular motion. However, the necessary radiation dose is higher than that associated with x-ray coronary angiography. Recently introduced prospective electrocardiograph (ECG)-triggered CT angiography (CTA), using conventional axial scan, can markedly reduce the radiation dose, while maintaining diagnostic performance, when appropriately applied in selected patients. The prospective ECG-triggered CTA is technically feasible in patients with low and stable heart rate. The indication for the CT examination should be exclusion of obstructive coronary disease, rather than analysis of ventricular and valvular function. The technique is most beneficial for young patients, especially young women, who are at low risk for significant coronary artery disease and for whom radiation dose is of great concern.     

High-pitch coronary CT angiography with third generation dual-source CT: limits of heart rate

To determine the average heart rate (HR) and heart rate variability (HRV) required for diagnostic imaging of the coronary arteries in patients undergoing high-pitch CT-angiography (CTA) with third-generation dual-source CT. Fifty consecutive patients underwent CTA of the thoracic (n = 8) and thoracoabdominal (n = 42) aorta with third-generation dual-source 192-slice CT with prospective electrocardiography (ECG)-gating at a pitch of 3.2. No β-blockers were administered. Motion artifacts of coronary arteries were graded on a 4-point scale. Average HR and HRV were noted. The average HR was 66 ± 11 beats per minute (bpm) (range 45–96 bpm); the HRV was 7.3 ± 4.4 bpm (range 3–20 bpm). Interobserver agreement on grade of image quality for the 642 coronary segments evaluated by both observers was good (κ = 0.71). Diagnostic image quality was found for 608 of the 642 segments (95 %) in 43 of 50 patients (86 %). In 14 % of the patients, image quality was nondiagnostic for at least one segment. HR (p = 0.001) was significantly higher in patients with at least one non-diagnostic segment compared to those without. There was no significant difference (p > 0.05) in HRV between patients with nondiagnostic segments and those with diagnostic images of all segments. All patients with a HR < 70 bpm had diagnostic image quality in all coronary segments. The effective radiation dose and scan time for the heart were 0.4 ± 0.1 mSv and 0.17 ± 0.02 s, respectively. Third-generation dual-source 192-slice CT allows for coronary angiography in the prospectively ECG-gated high-pitch mode with diagnostic image quality at HR up to 70 bpm. HRV is not significantly related to image quality of coronary CTA.     

High-pitch dual-source CT coronary angiography: analysis of the impact on image quality of altered electrocardiography waves during data acquisition

Electrocardiography (ECG) “altered waves” sometimes occur during data acquisition when computed tomography coronary angiography (CTCA) is performed with the prospectively ECG-triggered high-pitch (Flash spiral) mode using a second-generation dual-source CT. The aim of this study was to assess the effect of the ECG altered waves on image quality. Seventy-three consecutive patients with stable sinus rhythm ≤65 beats per minute were retrospectively enrolled in this study. CTCA was performed using the Flash spiral mode in which the data acquisition was prospectively triggered at 60 % of the R–R interval and completed within one cardiac cycle. The ECG waves before and during data acquisition were analyzed for grouping purposes. Image quality was evaluated using a four-point scale (1 = best, 4 = unevaluatable). Thirty patients (group 1) were found to have ECG altered waves during data acquisition, while 43 patients (group 2) had ECG “stable waves.” The altered waves were seen as the baseline drifting; the broad, erected, or inverted P wave or QRS complexes; and a new wave. However, the length of the R–R interval did not change during the data acquisition. There were no significant differences in image quality scores between the two groups on the per-patient (2 ± 0.87 vs. 2.2 ± 0.74, P = 0.273) or per-segment (1.27 ± 0.54 vs. 1.32 ± 0.55, P = 0.577) basis. There were no significant differences in coronary evaluatability as well (per-patient; 93.3 vs. 95.3 %, P = 0.352; per-segment; 99.4 vs. 99.6 %, P = 1.0). CTCA image quality is not affected by ECG altered waves during data acquisition using the Flash spiral mode in low and stable heart rate patients. Thus, the ECG altered waves are considered artifacts.     

双源CT冠状动脉成像中前瞻性与回顾性心电触发模式的比较

  目的  比较前瞻性心电触发序列扫描与回顾性心电触发螺旋扫描模式在双源CT冠状动脉成像中的图像质量及放射线剂量。  方法  将70例临床怀疑或已知冠心病的患者随机分为两组, 每组35例, 分别行前瞻性心电触发序列扫描和回顾性心电触发螺旋扫描冠状动脉CT成像, 对两种成像模式的图像质量及放射线剂量进行评价。  结果  两组患者的性别、年龄、体重指数匹配性良好, 差异无统计学意义(P > 0.05)。前瞻性心电触发序列扫描模式组和回顾性心电触发螺旋扫描模式组可评价的冠状动脉节段显示率分别为99.62%和99.62%, 两组间差异无统计学意义(χ²=0.000, P=1.000);两组图像质量评分分别为1.13±0.36和1.04±0.24, 差异有统计学意义(Z=-5.073, P=0.000);前瞻性心电触发序列扫描模式的放射线剂量为(3.47±1.00)mSv, 明显低于回顾性螺旋扫描模式的(14.28±1.81)mSv(P=0.032)。  结论  对于心律齐且心率≤ 70次/min的患者, 尽管前瞻性心电触发序列扫描的图像质量略差于回顾性螺旋扫描模式, 但两者可评价的冠状动脉节段显示率无明显差异, 而前者的有效放射剂量明显减少。     

Evaluation of high-pitch flash scan for pulmonary venous CTA on a 128-slice dual source CT: compared with prospective ECG-triggered sequence scan

To compare the image quality (IQ) and radiation dose of high-pitch scan and prospective ECG-triggered sequence scan on a 128-slice DSCT system for patients with atrial fibrillation (AF). Pulmonary venous (PV) CTA was performed with two protocols, including high-pitch scan and prospective ECG-triggered sequence scan. For each protocol, 20 sex, age and body-mass-index (mean 24.2 kg/m²) matched patients were identified. Two experienced radiologists, who were blinded to the scan protocols, independently graded the CT images of the two groups by a 5-point scale for subjective IQ assessment. Measured CT attenuation (Hounsfield units ± standard deviation), signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) at various anatomic locations were also recorded for objective IQ evaluation. Radiation exposure parameters [dose length product (DLP) and effective radiation dose (ERD)] were compared. Twenty-three patients (57.5 %) showed an ECG pattern of AF in total. Subjective IQ was rated excellent in 100 % for the high-pitch scan group, while minor step artifacts were observed in two patients (10 %) with arrhythmia for the prospective ECG-triggered sequence group. There was no significant difference on IQ, neither by subjective, nor by objective measures (SNR, CNR) between the two groups. The ERD of high-pitch flash scan and prospective ECG-triggered sequence scan were 0.9 (±0.25) and 2.9 (±0.69) mSv, respectively. Significantly lower radiation was achieved by using high-pitch flash scan (P < 0.05). High-pitch flash scan can provide similar subjective and objective IQ compared with prospective ECG-triggered sequence scan for PV CTA, while radiation exposure was significantly reduced.     

第二代双源CT前门控大螺距冠状动脉成像中ECG"不稳定波形"对图像质量的影响

目的 评估第二代双源CT前门控大螺距冠状动脉成像(Flash模式)中ECG呈现的"不稳定波形"对图像质量的影响。方法 回顾分析Flash模式冠状动脉成像的73例连续病例,与采集数据前ECG波形比较,观察采集数据的单个R-R间期中波形变化。采用4级法评估图像质量。结果 组1(30例)为"不稳定波形"组,组2(43例)为"稳定波形"组。"不稳定波形"发生于数据采集时和(或)数据采集完成后,表现为基线抬高或下移,P波或QRS波群倒置、宽大畸形,T波~P波之间无命名的波形,波形呈M形、W形、V形或∧形,但R-R间期无变化。以血管段及患者为单位,两组间图像质量评分的差异均无统计学意义(P均>0.05);可评估率的差异无统计学意义(P均>0.05)。结论 前门控大螺距冠状动脉成像时,仅在图像采集R-R间期呈现的ECG"不稳定波形"可能为伪差,不对图像质量产生明显影响。     

Myocardial ischemia detection with single-phase CT perfusion in symptomatic patients using high-pitch helical image acquisition technique

Coronary CT angiography (CCTA) suffers from a reduced diagnostic accuracy in patients with heavily calcified coronary arteries or prior myocardial revascularisation due to artefacts caused by calcifications and stent material. CT myocardial perfusion imaging (CTMPI) yields high potential for the detection of myocardial ischemia and might help to overcome the above mentioned limitations. We analysed CT single-phase perfusion using high-pitch helical image acquisition technique in patients with prior myocardial revascularisation. Thirty-six patients with an indication for invasive coronary angiography (28 with coronary stents, 2 with coronary artery bypass grafts and 6 with both) were included in this prospective study at two study sites. All patients were examined on a 2nd generation dual-source CT system. Stress CT images were obtained using a prospectively ECG-triggered single-phase high-pitch helical image acquisition technique. During stress the tracer for myocardial perfusion (MP) SPECT imaging was administered. Rest CT images were acquired using prospectively ECG-triggered sequential CT. MP-SPECT imaging and invasive coronary angiography served as standard of reference. In this heavily diseased patient cohort CCTA alone showed a low overall diagnostic accuracy for detection of hemodynamically relevant coronary artery stenosis of only 31% on a per-patient base and 60% on a per-vessel base. Combining CCTA and CTMPI allowed for a significantly higher overall diagnostic accuracy of 78% on a per-patient base and 92% on a per-vessel base (p?<?0.001). Mean radiation dose for stress CT scans was 0.9 mSv, mean radiation dose for rest CT scans was 5.0 mSv. In symptomatic patients with known coronary artery disease and prior myocardial revascularization combining CCTA and CTMPI showed significantly higher diagnostic accuracy in detection of hemodynamically significant coronary artery stenosis when compared to CCTA alone.     

双源CT前瞻性心电触发大螺距扫描腹部血管成像

目的 探讨双源CT前瞻性心电触发大螺距扫描应用于腹部CTA的可行性。方法 将40例临床疑诊腹部血管疾病、接受腹部CTA检查的患者随机分为2组,对A组采用前瞻性心电触发大螺距模式扫描,B组采用常规螺旋模式扫描,分别测量两组腹主动脉、腹腔干、脾动脉、肠系膜上动脉、右肾动脉、左肾动脉、腹主动脉分叉处、背部肌肉CT值及图像噪声,记录扫描时间及剂量长度乘积,并计算SNR、CNR和有效辐射剂量(ED)。比较两组各动脉的CT值、噪声、SNR、CNR、扫描时间、ED及图像质量差异。结果 两组腹主动脉、腹腔干、脾动脉、肠系膜上动脉、右肾动脉、左肾动脉、腹主动脉分叉处的CT值、SNR、CNR和图像质量差异均无统计学意义(P均>0.05),图像噪声、扫描时间及ED差异均有统计学意义(P均<0.05)。与B组相比,A组的扫描时间缩短86.45%、ED降低72.56%。结论 双源CT前瞻性心电触发大螺距扫描腹部CTA可在获得能够满足临床诊断要求图像的前提下大幅度降低患者的辐射剂量。     

Computed tomography coronary angiography with a consistent dose below 2 mSv using double prospectively ECG-triggered high-pitch spiral acquisition in patients with atrial fibrillation: initial experience

To evaluate the feasibility and imaging quality of double prospectively ECG-triggered high-pitch spiral acquisition mode (double flash mode) for coronary computed tomography angiography (CTCA) in patients with atrial fibrillation (AF). 47 patients (11 women, 36 men; mean age 64.5 ± 12.1 years) were enrolled for CTCA examinations using a dual-source CT with 2 × 128 × 0.6 mm collimation, 0.28 s rotation time and a pitch of 3.4. Double flash mode was prospectively triggered first at 60 % and later at 30 % of the R–R interval within two cardiac cycles. Image quality was evaluated using a four-point scale (1 = excellent, 4 = non-assessable). From 672 coronary artery segments, 77.5 % (521/672) was rated as score of 1, 20.8 % (140/672) as score of 2, 1.2 % (8/672) as score of 3 and 0.4 % (3/672) was rated as ‘non-assessable’. The average image quality score was 1.25 ± 0.38 on a per segment basis. Mean dose-length product for CTCA was 92.6 ± 28.2 mGy cm, the effective dose was 1.30 ± 0.39 mSv (0.64–1.97 mSv). In patients with AF, double prospectively ECG-triggered high-pitch spiral acquisition mode could be a feasible and valuable scan mode for CTCA with a consistent dose below 2 mSv as well as diagnostic imaging quality.     

Preprocedural coronary CT angiography significantly improves success rates of PCI for chronic total occlusion

Chronic total occlusions of coronary arteries occur in about 20 % of patients with suspected coronary artery disease and are more frequent with increasing age. The success rate of interventions is lower (55–80 %) compared to conventional lesions (>90 %). Coronary CT angiography (coronary CTA) provides information about the occluded segment, which cannot be obtained from invasive angiograms (XA). We therefore hypothesized that preprocedural coronary CTA may improve success rates of percutaneous coronary intervention (PCI) for coronary arteries (CTO). 30 patients with chronic total coronary artery occlusions (mean age 73 years, 26 men) and predicted high complexity were imaged by coronary CTA prior to PCI for CTO. CT data sets were acquired with a 64 detector row dual source scanner and retrograde ECG gating, 0.6 mm collimation and z-flying focal spot, yielding isovoxel spatial resolution of about 0.4 mm. Based on the CT data sets, established complexity criteria for CTO (Euro CTO club, Di Mario et al. in EuroIntervention 3(1):30–43, 2007) were evaluated and compared to invasive coronary angiography. Three-dimensional volume-rendered images of the occluded coronary artery were displayed in the catheterization lab during PCI to guide the advancement of the wire. PCI success, defined as the ability to advance the guide wire into the distal lumen with thrombolysis in myocardial infarction III flow was compared to 43 controls without coronary CTA using propensity score matching based on established criteria of procedural success. The course of the occluded segments was visualized by coronary CTA in all cases. Calcification, lesion length, stump morphology and presence of side branches were underestimated by invasive angiograms when compared to coronary CTA. PCI success rate in 30 patients who underwent pre-procedural CTA was significantly higher than in patients without prior coronary CTA [unmatched: CT 90 % (27/30) vs. no CT 63 % (27/43), p = 0.009; matched: CT 88 % (22/25) vs. no CT 64 % (16/25) p = 0.03]. Through information not readily seen on invasive coronary angiography, coronary CTA can significantly enhance success rates of PCI for CTO.     

双源CT自适应前瞻性心电触发序列扫描冠脉成像的临床应用

目的：评价第二代双源CT自适应前瞻性心电触发序列扫描冠脉成像的临床应用价值。方法：回顾性分析114例第二代双源CT自适应前瞻性心电触发序列扫描冠脉成像患者的图像,其中18例患者有2周内的冠脉造影对比。结果：本组114例患者检查过程中的平均心率为（63±8）次/min,图像平均质量评分为（1.65±0.59）分,优良图像占90.35%,可诊断图像占99.12%;96.53%（1 252/1 297）的冠脉节段达到可供诊断的图像质量;平均有效辐射剂量为（6.27±1.81） mSv;诊断冠心病38例,21例支架置入术后的48枚支架的通畅性得到评价,43枚支架通畅,4枚支架内再狭窄,1枚支架内闭塞;18例72支冠脉以冠脉造影为标准,双源CT冠脉成像诊断冠脉狭窄（按支）的敏感度、特异度、阳性预测值、阴性预测值分别为95.45%、96.00%、91.30%、97.96%。结论：第二代双源CT前瞻性心电触发序列扫描是一种安全、有效、低辐射、无创的冠脉成像技术,也是一种有效评价冠脉支架通畅性的方法。     

双源计算机断层摄影回顾性心电门控胸腹联合主动脉血管造影图像质量

  目的  评价双源计算机断层摄影(computed tomography, CT)回顾性心电门控胸腹联合主动脉血管造影对主动脉和冠状动脉的显示及放射剂量。  方法  回顾性分析2009年12月至2010年11月本院行主动脉计算机断层摄影血管造影(computed tomography angiography, CTA)患者45例, 其中回顾性心电门控胸部联合腹部扫描患者23例, 常规无心电门控主动脉CTA扫描患者22例, 比较两种不同扫描方式主动脉根部、主动脉弓、腹主动脉起始部、主动脉分叉部位的主动脉强化CT值, 比较两种不同扫描方式升主动脉部位图像噪音。采用3分制评分方法, 对主动脉根部及冠状动脉主要分支的图像质量进行评价, 比较两种不同扫描方式主动脉根部及冠状动脉图像质量; 并比较两种不同扫描方式的有效放射剂量。  结果  回顾性比较心电门控胸部联合腹部及常规无心电门控血管造影主动脉4个不同部位的CT值差异无显著意义, 主动脉根部分别为(280.8±63.4)和(329.3±43.2)HU, 主动脉弓分别为(288.9±60.9)和(320.7±47.6)HU, 腹主动脉起始部分别为(267.2±65.1)和(315.4±43.5)HU, 主动脉分叉分别为(293.3±75.2)和(322.7±45.8)HU, 均P > 0.05;常规无心电门控主动脉CTA扫描图像噪音(11.8±2.5)HU小于回顾性心电门控胸部联合腹部扫描的(19.3±4.8)HU, P=0.002。采用回顾性心电门控胸部联合腹部扫描, 主动脉根部及冠状动脉主要分支有较高的可评价率, 主动脉根部100%(23/23), 冠状动脉83%(19/23);明显高于常规无心电门控主动脉CTA扫描, 主动脉根部5%(1/22), 冠状动脉0%(0/22), P < 0.001。回顾性心电门控胸部联合腹部扫描的有效射线剂量明显高于常规无心电门控主动脉CTA扫描(P=0.038)。  结论  采用回顾性心电门控胸部联合腹部主动脉CTA扫描, 可以使全主动脉得到良好的强化, 能够清晰显示主动脉根部, 并可评价冠状动脉, 有效射线剂量高于无心电门控主动脉CTA。     

Assessment of image quality and radiation dose of prospectively ECG-triggered adaptive dual-source coronary computed tomography angiography (cCTA) with arrhythmia rejection algorithm in systole versus diastole: a retrospective cohort study

In this study, we sought to evaluate the image quality and effective radiation dose of prospectively ECG-triggered adaptive systolic (PTA-systolic) dual-source CTA versus prospectively triggered adaptive diastolic (PTA-diastolic) dual-source CTA in patients of unselected heart rate and rhythm. This retrospective cohort study consisted of 41 PTA-systolic and 41 matched PTA-diastolic CTA patients whom underwent clinically indicated 128-slice dual source CTA between December 2010 to June 2012. Image quality and motion artifact score (both on a Likert scale 1–4 with 4 being the best), effective dose, and CTDI_vol were compared. The effect of heart rate (HR) and heart rate variability [HRV] on image motion artifact score and CTDI_vol was analyzed with Pearson’s correlation coefficient. All 82 exams were considered diagnostic with 0 non-diagnostic segments. PTA-systolic CTA patients had a higher maximum HR, wider HRV, were less likely to be in sinus rhythm, and received less beta-blocker vs. PTA-diastolic CTA patients. No difference in effective dose was observed (PTA-systolic vs. PTA-diastolic CTA: 2.9 vs. 2.2 mSv, p = 0.26). Image quality score (3.3 vs. 3.5, p < 0.05) and motion artifact score (3.5 vs. 3.8, p < 0.05) were lower in PTA-systolic CTAs than in PTA-diastolic CTAs. For PTA-systolic CTAs, an increase in HR was not associated with a negative impact on motion artifact score nor CTDI_vol. For PTA-diastolic CTA, an increase in HR was associated with increased motion artifacts and CTDI_vol. HRV demonstrated no correlation with motion artifact and CTDI_vol for both PTA-systolic and PTA-diastolic CTAs. In conclusion, both PTA-diastolic CTA and PTA-systolic CTA yielded diagnostic examinations at unselected heart rates and rhythms with similar effective radiation, but PTA-systolic CTA resulted in more consistent radiation exposure and image quality across a wide range of rates and rhythms.     

German cardiac CT registry: indications,procedural data and clinical consequences in 7061 patients undergoing cardiac computed tomography

Cardiac computed tomography permits quantification of coronary calcification as well as detection of coronary artery stenoses after contrast enhancement. Moreover, cardiac CT offers high-resolution morphologic and functional imaging of cardiac structures which is valuable for various structural heart disease interventions and electrophysiology procedures. So far, only limited data exist regarding the spectrum of indications, image acquisition parameters as well as results and clinical consequences of cardiac CT examinations using state-of-the-art CT systems in experienced centers. Twelve cardiology centers with profound expertise in cardiovascular imaging participated in the German Cardiac CT Registry. Criteria for participation included adequate experience in cardiac CT as well of the availability of a 64-slice or newer CT system. Between 2009 and 2014, 7061 patients were prospectively enrolled. For all cardiac CT examinations, patient parameters, procedural data, indication and clinical consequences of the examination were documented. Mean patient age was 61?±?12 years, 63% were males. The majority (63%) of all cardiac CT examinations were performed in an outpatient setting, 37% were performed during an inpatient stay. 91% were elective and 9% were scheduled in an acute setting. In most examinations (48%), reporting was performed by cardiologists, in 4% by radiologists and in 47% of the cases as a consensus reading. Cardiac CT was limited to native acquisitions for assessment of coronary artery calcification in 9% of patients, only contrast-enhanced coronary CT angiography was performed in 16.6% and combined native and contrast-enhanced coronary CT angiography was performed in 57.7% of patients. Non-coronary cardiac CT examinations constituted 16.6% of all cases. Coronary artery calcification assessment was performed using prospectively ECG-triggered acquisition in 76.9% of all cases. The median dose length product (DLP) was 42 mGy cm (estimated effective radiation dose of 0.6 mSv). Coronary CT angiography was performed using prospectively ECG-triggered acquisition in 77.3% of all cases. Tube voltage was 120 kV in 67.8% of patients and 100 kV in 30.7% of patients, with a resultant median DLP of 256 mGy cm (estimated effective dose of 3.6 mSv). Clinical consequences of cardiac CT were as follows: in 46.8% of the cases, invasive coronary angiography could be avoided; ischemia testing was recommended in 4.7% of the cases, invasive coronary angiography was recommended in 16.4% of the cases and change in medication in 21.6% of the examinations. Cardiac CT is performed in the majority of patients for non-invasive evaluation of the coronary arteries. CT frequently resulted in medication change, and otherwise planned downstream testing including invasive angiography could be avoided in a high percentage of patients. Radiation exposure in experienced centers is relatively low.     

Non-invasive assessment of atherosclerotic coronary lesion length using multidetector computed tomography angiography: comparison to quantitative coronary angiography

Multidetector computed tomography angiography (CTA) provides information on plaque extent and stenosis in the coronary wall. More accurate lesion assessment may be feasible with CTA as compared to invasive coronary angiography (ICA). Accordingly, lesion length assessment was compared between ICA and CTA in patients referred for CTA who underwent subsequent percutaneous coronary intervention (PCI). 89 patients clinically referred for CTA were subsequently referred for ICA and PCI. On CTA, lesion length was measured from the proximal to the distal shoulder of the plaque. Quantitative coronary angiography (QCA) was performed to analyze lesion length. Stent length was recorded for each lesion. In total, 119 lesions were retrospectively identified. Mean lesion length on CTA was 21.4 ± 8.4 mm and on QCA 12.6 ± 6.1 mm. Mean stent length deployed was 17.4 ± 5.3 mm. Lesion length on CTA was significantly longer than on QCA (difference 8.8 ± 6.7 mm, P < 0.001). Moreover, lesion length visualized on CTA was also significantly longer than mean stent length (CTA lesion length-stent length was 4.2 ± 8.7 mm, P < 0.001). Lesion length assessed by CTA is longer than that assessed by ICA. Possibly, CTA provides more accurate lesion length assessment than ICA and may facilitate improved guidance of percutaneous treatment of coronary lesions.     

Triple rule-out acute chest pain evaluation using a 320-row-detector volume CT: a comparison of the wide-volume and helical modes

The purpose of this study was to investigate the image quality and radiation dose of triple rule-out computed tomography (TROCT) using a 320-row-detector volume CT system to compare the wide-volume and helical modes of this CT system. Sixty-four patients with noncritical chest pain were allocated to one of 2 groups according to the type of CT examination mode used. Group 1 patients were examined using the wide-volume (non-spiral) mode and group 2 patients were examined using the 160-detector row helical mode, with the same contrast injection protocol in both methods [biphasic injection protocol; injection rate of 4 ml/s, median volume, 70 ml (range 65–100 ml)]. Attenuations of the pulmonary trunk, ascending aorta, and coronary arteries were measured in Hounsfield units; a subjective overall patient-based image quality score of 1–3 was awarded to each study. Effective doses, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Average effective dose was significantly lower in group 1 than group 2 (9.7 ± 5.1 vs. 16 ± 5.9 mSv, P < 0.001). The mean attenuation of the main pulmonary trunk was significantly higher in group 1 than group 2 (P = 0.04) and mean attenuations in other vessels were not significant different. SNR and CNR were not significantly different between the groups. The proportion of diagnostic image qualities for chest CT angiography (CTA) was similar between the groups (93.5 vs. 93.9 %). In coronary CTA, group 1 showed a higher proportion of diagnostic image qualities than group 2 (100 vs. 87.9 %). The use of wide-volume mode of 320-detector CT reduces the overall effective radiation dose and results in similar attenuation and image quality for TROCT as compared with the helical mode.     

Patterns of coronary arterial lesion calcification by a novel, cross-sectional CT angiographic assessment

To investigate the patterns and diagnostic implications of coronary arterial lesion calcification by CT angiography (CTA) using a novel, cross-sectional grading method, we studied 371 patients enrolled in the CorE-64 study who underwent CTA and invasive angiography for detecting coronary artery stenoses by quantitative coronary angiography (QCA). The number of quadrants involving calcium on a cross-sectional view for ≥30 and ≥50 % lesions in 4,511 arterial segments was assessed by CTA according to: noncalcified, mild (one-quadrant), moderate (two-quadrant), severe (three-quadrant) and very severe (four-quadrant calcium). Area under the receiver operating characteristic curve (AUC) were used to evaluate CTA diagnostic accuracy and agreement versus. QCA for plaque types. Only 4 % of ≥50 % stenoses by QCA were very severely calcified while 43 % were noncalcified. AUC for CTA to detect ≥50 % stenoses by QCA for non-calcified, mildly, moderately, severely, and very severely calcified plaques were 0.90, 0.88, 0.83, 0.76 and 0.89, respectively (P < 0.05). In 198 lesions with severe calcification, the presence or absence of a visible residual lumen by CTA was associated with ≥50 % stenosis by QCA in 20.3 and 76.9 %, respectively. Kappa was 0.93 for interobserver variability in evaluating plaque calcification. We conclude that calcification of individual coronary artery lesions can be reliably graded using CTA. Most ≥50 % coronary artery stenoses are not or only mildly calcified. If no residual lumen is seen on CTA, calcified lesions are predictive of ≥50 % stenoses and vice versa. CTA diagnostic accuracy for detecting ≥50 % stenoses is reduced in lesions with more than mild calcification due to lower specificity.     

Anatomical versus functional assessment of coronary artery disease: direct comparison of computed tomography coronary angiography and magnetic resonance myocardial perfusion imaging in patients with intermediate pre-test probability

Computed tomography coronary angiography (CTA) and cardiac magnetic resonance myocardial perfusion imaging (CMR-MPI) are state-of-the-art tools for noninvasive assessment of coronary artery disease (CAD). We aimed to compare the diagnostic accuracy of CTA and CMR-MPI for the detection of functionally relevant CAD, using invasive coronary angiography (XA) with fractional flow reserve (FFR) as a reference standard, and to evaluate the best protocol integrating these techniques for assessment of patients with suspected CAD. 95 patients (68 % men; 62 ± 8.1 years) with intermediate pre-test probability (PTP) of CAD underwent a sequential protocol of CTA, CMR-MPI and XA. Significant CAD was defined as >90 % coronary stenosis, 40–90 % stenosis with FFR ≤ 0.80 or left main stenosis ≥50 %. Prevalence of significant CAD was 43 %. CTA was more sensitive (100 %) but less specific (59 %) than CMR-MPI (88 and 89 %, respectively) for detection of significant CAD, with a strong trend for higher global diagnostic accuracy of CMR-MPI (88 vs. 77 %, p = 0.05). An integrated approach based on an initial CTA and subsequent referral to CMR-MPI of positive/inconclusive results had the best diagnostic performance (AUC 0.91). The direct referral to XA of patients with positive/inconclusive CTA performed worse than a selective approach based on CMR-MPI results (AUC 0.80 vs. 0.91, p = 0.005). In this intermediate PTP population, CMR-MPI showed a strong trend toward better performance compared to CTA for the assessment of functionally significant CAD. A combined protocol integrating coronary anatomy and function seems to be a very effective approach in the accurate diagnosis of CAD.     

Coronary CT angiography using the second-generation 320-detector row CT: assessment of image quality and radiation dose in various heart rates compared with the first-generation scanner

To assess the image quality and radiation dose reduction in various heart rates in coronary CT angiography using the second-generation 320-detector row CT compared with the first-generation CT. Ninety-six patients were retrospectively included. The first 48 patients underwent coronary CT angiography with the first-generation 320-detector row CT, while the last 48 patients underwent with the second-generation CT. Subjective image quality was graded using a 4-point scale (4, excellent; 1, unable to evaluate). Image noise and contrast-to-noise ratio were also analyzed. Subgroup analysis was performed based on the heart rate. The mean effective dose was derived from the dose length product multiplied by a conversion coefficient for the chest (κ = 0.014 mSv × mGy^?1 × cm^?1). The overall subjective image quality score showed no significant difference (3.66 vs 3.69, respectively, p = 0.25). The image quality score of the second-generation group tended to be higher than that of the first-generation group in the 66- to 75-bpm subgroup (3.36 vs 3.53, respectively, p = 0.07). No significant difference was observed in image noise and contrast-to-noise ratio. The overall radiation dose reduced by 24 % (3.3 vs 2.5 mSv, respectively, p = 0.03), and the reduction was substantial in patients with higher heart rate (66- to 75-bpm, 4.3 vs 2.2 mSv, respectively, p = 0.009; >75 bpm, 8.2 vs 3.7 mSv, respectively, p = 0.005). The second-generation 320-detector row CT could maintain the image quality while reducing the radiation dose in coronary CT angiography. The dose reduction was larger in patients with higher heart rate.