Differences between normal subjects and patients with coronary artery disease for three different MR coronary angiography respiratory suppression techniques.

A comparison between three magnetic resonance coronary angiography (MRCA) respiratory motion suppression techniques was performed for both normal subjects and patients with coronary artery disease (CAD). MRCA images were acquired in 17 normal subjects and 15 patients with CAD, using conventional breath-hold MRCA, navigator echo (NE)-guided breath-hold MRCA (LED feedback), and NE-gated MRCA during free respiration. Image quality, diaphragm registration, and total acquisition time were assessed. Overall, there was poor diaphragm registration for conventional breath-holding compared with free respiration (P < 0.001). CAD patients found it significantly more difficult to perform a steady breath-hold (P = 0.04) or attain the same diaphragm position over multiple breath-holds than normal subjects (P = 0.02). All normal subjects, but only 3 of the 15 CAD patients, were able to perform the LED feedback technique (P < 0.001). For normal subjects, image quality was similar between the three respiratory suppression techniques (P = 0.3), while for CAD patients there was an improvement in image quality, for images acquired during free respiration (breath-hold vs. free respiration, P < 0.01). There was no significant difference in the total acquisition times between the breath-hold and free respiration techniques (P = 0.2). There were substantial differences in the effectiveness of MRCA respiratory suppression techniques between normal subjects and CAD patients. In patients, only NE-gated MRCA performed well, requiring minimal cooperation with no increase in total acquisition time. Validation of NE-MRCA techniques should always be performed in patients, as well as normal subjects, to ensure correct evaluation of the technique for the target population.     

中等心率下64层螺旋CT 前瞻性心电门控冠状动脉成像的可行性研究

目的 采用回顾性心电门控模拟前瞻性心电门控冠状动脉CT 成像(CCTA),探讨前瞻性心电门控CCTA 在中等心率病人中的可行性.方法 本研究共纳入63 例病人[心率(HR)为65～75 次/min,心率变异性(HRv)＜5次/min,钙化积分＜400 分]行回顾性心电门控CCTA,扫描结束后以R-R 间期60%的相位为中心,按400 ms 占据曝光平均心率R-R 间期的比例以5%的间隔重建期相,以冠状动脉节段为单位,对所有重建的图像进行评分(5 分制:5分为优,1 分为差),以统计描述可用于诊断的冠状动脉节段数目所占比例评价前瞻性心电门控CCTA 在中等心率病人中的应用价值.结果 共有822 个冠状动脉节段参与评分,平均得分4.15±0.72,可用于诊断的冠状动脉节段数目比例为97.76%.结论 中等心率下前瞻性心电门控技术可通过预设60%采集期相,重叠时间设置为200 ms 可以重建出满足诊断的图像,且理论上可以大幅降低辐射剂量.     

Evaluation of three-dimensional navigator-gated whole heart MR coronary angiography: the importance of systolic imaging in subjects with high heart rates

PURPOSE: To evaluate the influence of heart rate (HR) on magnetic resonance coronary angiography (MRCA) image quality in diastolic and systolic phases. MATERIALS AND METHODS: Twenty-seven healthy volunteers (9 men; 33+/-9 years, HR 53-110 bpm), were evaluated with the electrocardiography and three-dimensional navigator-gating MRCA in a 1.5-T MR scanner (Avanto, Siemens) in diastolic and systolic phases (steady-state free precession; TR/TE/flip angle=3.2 ms/1.6 ms/90 degrees). The timing of scanning was individually adapted to the cardiac rest periods obtained in the prescanning, by visually identifying when the movement of right coronary artery was minimized during diastole and systole. Images of two phases were side-by-side compared on a four-point scale (from 1=poor to 4=excellent visibility; score of 3 or 4 as diagnostic). RESULTS: Of 13 subjects with HR < or =65 bpm (low HR group, mean 59.8+/-4.9 bpm, range 53-65), the image quality scores were significantly better than that with higher heart rates (73.9+/-9.0 bpm, range 68-110) in diastolic MRCA. The image quality was significantly improved during systole in high HR group. Overall, 91.3% of low HR group had MRCA image of diagnostic quality acquired at diastole, while 88.3% of high HR group had diagnostic images at systole by segmental analysis (p=NS). CONCLUSIONS: MRCA at systole offered superior quality in patients with high heart rates.     

Prospective adaptive navigator correction for breath-hold MR coronary angiography

Current MR coronary angiography (MRCA) methods use breath-holding to minimize respiratory motion. A major limitation to this technique is misregistration between imaging slices due to breath-hold variability. Prospective adaptive correction of image location using real-time navigator measurement of diaphragm position is a potential method for improving slice registration in breath-hold MRCA. Ten subjects underwent MRCA using an ECG-gated, fat-suppressed, segmented k-space, gradient-echo sequence. Transverse and coronal images were acquired using standard breath-holding with and without prospective navigator correction. Breath-hold MRCA with prospective navigator correction resulted in a 47% reduction in craniocaudal slice registration error compared to standard breath-holding (0.9 ± 0.2 mm versus 1.7 2 0.4 mm, P = 0.04). Prospective adaptive navigator correction of image location significantly improves slice registration for breath-hold MRCA and is a promising motion correction technique for cardiac MR.     

Automated monitoring of diaphragm end-expiratory position for real-time navigator echo MR coronary angiography

Real-time navigator echo (NE)-gated magnetic resonance coronary angiography (MRCA) during free respiration is now possible. However, the mean diaphragm end-expiratory position (DEEP) drifts over time, and this results in a reduction in scanning efficiency and increased artifacts due to the acquisition of data during periods of high diaphragm velocity. To address these problems, a diaphragm monitoring program that follows the mean DEEP over time has been developed. Fifteen subjects with ischemic heart disease underwent continuous NE monitoring of their diaphragm for 30 minutes. Using these diaphragm traces, theoretical MRCA scans were performed. Several diaphragm monitoring algorithms were developed and compared with the simplest case (a stationary 5 mm NE acceptance window placed around the mean DEEP, as measured by NE monitoring at the outset of the scan). An overall scan efficiency was calculated, and the number of completed scans where the mean DEEP lay within the NE acceptance window was recorded. Of the six algorithms considered, the most effective one monitored the mean DEEP and prospectively placed the upper limit of the NE acceptance window on this position for the subsequent acquisition. Using this algorithm in comparison with the simplest stationary scenario, both scan efficiency (47.9% vs. 38.5%, P = 0.01) and the number of completed scans where the mean DEEP lay within the NE acceptance window (71.2 vs. 30.3, P < 0.001) were improved. The implementation of such a monitoring algorithm, in combination with adaptive motion correction techniques, should improve overall scan efficiency while maintaining the end-expiratory position at the top end of the NE acceptance window, to reduce image artifacts.     

中等心率下64层螺旋CT前瞻性心电门控冠状动脉成像的可行性研究

目的采用回顾性心电门控模拟前瞻性心电门控冠状动脉CT成像（CCTA）,探讨前瞻性心电门控CCTA在中等心率病人中的可行性。方法本研究共纳入63例病人[心率（HR）为65～75次/min,心率变异性（HRv）〈5次/min,钙化积分〈400分]行回顾性心电门控CCTA,扫描结束后以R-R间期60%的相位为中心,按400ms占据曝光平均心率R-R间期的比例以5%的间隔重建期相,以冠状动脉节段为单位,对所有重建的图像进行评分（5分制：5分为优,1分为差）,以统计描述可用于诊断的冠状动脉节段数目所占比例评价前瞻性心电门控CCTA在中等心率病人中的应用价值。结果共有822个冠状动脉节段参与评分,平均得分4.15±0.72,可用于诊断的冠状动脉节段数目比例为97.76%。结论中等心率下前瞻性心电门控技术可通过预设60%采集期相,重叠时间设置为200ms可以重建出满足诊断的图像,且理论上可以大幅降低辐射剂量。     

A comparison between segmented k-space FLASH and interleaved spiral MR coronary angiography sequences

A direct comparison of segmented fast low-angle short (FLASH) imaging and interleaved spiral magnetic resonance coronary angiography (MRCA) during free respiration using navigator echo has been performed. MRCA images were acquired in 30 normal subjects and 15 patients with coronary artery disease (CAD). Images of the right coronary artery were acquired during free respiration using navigator echo gating for both a segmented k-space FLASH sequence (8 views/segment, segment duration 105 msec) and an interleaved spiral sequence (20 interleaves, spiral read-out period 19 msec). Image quality was scored by three independent blinded observers, and coronary artery signal-to-noise ratio (SNR) and coronary artery/epicardial fat contrast-to-noise ratio (CNR) were measured. There was a significant improvement in image quality when coronary images were acquired with the interleaved spiral sequence (spiral 2. 3 vs. FLASH 1.8; P = 0.002). This was associated with an increase in the coronary artery SNR (16.6 +/- 6.9 vs. 11.8 +/- 5.0; P < 0.001), the coronary artery/epicardial fat CNR (12.5 +/- 6.1 vs. 7.4 +/- 4.0, P < 0.001), and the image resolution (256 x 256 vs. 256 x 128). However, there was a 12% increase in acquisition time for the interleaved spiral sequence. Image quality, SNR, CNR, and resolution can be improved using an interleaved spiral sequence. These improvements are secondary to the intrinsic characteristics of spiral imaging and the short acquisition period, which reduces the effects of both cardiac and respiratory motion.     

Navigator echo-based respiratory gating for three-dimensional MR coronary angiography: reduction of scan time using a slice interpolation technique

PURPOSE: The aim of the study was to compare a conventional respiratory-gated 3D MR coronary angiographic technique (conventional MRCA) with a respiratory-gated 3D MR coronary angiographic technique that includes a slice interpolation technique (slice interpolation MRCA). Both MRCA techniques were compared based on the quality of visualization of the coronary arteries and the diagnostic accuracy in identifying hemodynamically significant coronary artery stenoses. METHOD: Forty patients with known proximal coronary artery stenosis after conventional CA were examined on a 1.5 T scanner, that is, 20 patients with each sequence. A 6 point grading system (0 = worst quality, 5 = best quality) was used to evaluate and compare the image quality. The length and proximal diameter of the depicted coronary arteries were measured. Detection of coronary artery stenoses was compared with that obtained by conventional CA by two blinded readers. RESULTS: With the slice interpolation technique, the average scan time of the entire heart was reduced by approximately 40%. With use of conventional MRCA, 69% of all proximal and middle coronary artery segments were visualized with a sufficient image quality; with the slice interpolation technique, 79% of these segments were depicted adequately. For the assessment of stenoses, sensitivity was 71% and specificity was 53% for conventional MRCA and 72 and 60% for slice interpolation MRCA, respectively. These differences in sensitivity and specificity were statistically not significant. CONCLUSION: The application of a slice interpolation technique reduces the scan time, maintains a comparable sensitivity and specificity for the assessment of coronary artery stenoses, and increases the number of completely identified coronary artery segments compared with the conventional technique.     

Compression belt for navigator-triggered trueFISP whole-heart coronary magnetic resonance angiography: study in healthy volunteers.

PURPOSE: To evaluate in healthy volunteers the usefulness of an abdominal compression belt in reducing acquisition time by stabilizing respiratory motion during whole-heart coronary magnetic resonance angiography (WHCMRA) using conventional navigator triggering. METHODS: In 10 healthy volunteers, we performed free-breathing 3-dimensional segmented true fast imaging with steady-state precession (trueFISP) WHCMRA using conventional navigator triggering without motion-adapted gating. We acquired images with the abdominal compression belt rolled tightly around the upper abdomen and without the belt. We compared image acquisition time, navigator efficiency, and visible length of coronary arteries using paired t-test and subjective image quality on a 4-point scale (1, poor; 4, excellent) using Wilcoxon signed-rank test. RESULTS: There were no statistically significant differences for mean acquisition time (11.5+/-5.0 vs. 9.3+/-2.4 min, P=0.150); navigator efficiency (38.7+/-13.6 vs. 42.8+/-11.0%, P=0.336); mean overall visible length of the coronary arteries (99.7+/-22.7 vs. 105.0+/-16.5 mm, P=0.530); or mean overall subjective image quality (2.5 vs. 2.7, P=0.297) between results obtained with and without the abdominal compression belt. CONCLUSION: In this small group of healthy volunteers, the use of an abdominal compression belt did not reduce image acquisition time or improve image quality in trueFISP WHCMRA using conventional navigator triggering; however, the technique's feasibility requires additional consideration using other navigator-triggering methods for patients with irregular respiratory cycles.     

Computed tomography coronary angiography with 370-millisecond gantry rotation time: evaluation of the best image reconstruction interval

OBJECTIVE: To evaluate the best reconstruction window for noninvasive coronary angiography when using a 16-detector row computed tomography (CT) scanner with a gantry rotation time of 370 milliseconds. METHODS: In a pilot study, 189 coronary artery segments of 21 patients with a mean heart rate of 65 beats per minute (bpm, maximum: 45-94 bpm) were investigated using a 16-detector row CT scanner. Raw data were reconstructed in 10% increments from 40% to 70% of the RR interval. Two experienced observers independently evaluated the image quality of the coronary arteries in a segmental fashion. A 5-point ranking scale was applied, with 1 being very poor (no evaluation possible); 2, poor; 3, moderate; 4, good; and 5, very good. RESULTS: In the mean of all patients, the best reconstruction window was found to be at 60% of the RR interval. In patients with higher heart rates, the best reconstruction window was found to be at an earlier stage of the R wave-to-R wave interval. CONCLUSIONS: Initial results show that good diagnostic image quality could be achieved for all evaluated segments of the coronary tree with image reconstructions at 60% of the R wave-to-R wave interval in patients with heart rates of 70 bpm or less. Using a 16-detector row CT scanner with a gantry rotation time of 370 milliseconds, the need for adapting the reconstruction window to each segment for the best image quality was overcome in those cases. In patients with heart rates faster than 70 bpm, reconstructions at an earlier stage within the cardiac cycle were necessary.     

Noninvasive coronary angiography using 64-slice spiral computed tomography in an unselected patient collective: effect of heart rate, heart rate variability and coronary calcifications on image quality and diagnostic accuracy

OBJECTIVE: The aim of this study was to assess the impact of heart rate, heart rate variability and calcification on image quality and diagnostic accuracy in an unselected patient collective. SUBJECTS AND METHODS: One hundred and two consecutive patients with known or suspected coronary artery disease underwent both 64-MSCT and invasive coronary angiography. Image quality (IQ) was assessed by independent observers using a 4-point scale from excellent (1) to non-diagnostic (4). Accuracy of MSCT regarding detection or exclusion of significant stenosis (>50%) was evaluated on a per segment basis in a modified AHA 13-segment model. Effects of heart rate, heart rate variability, calcification and body mass index (BMI) on IQ and accuracy were evaluated by multivariate regression. IQ and accuracy were further analysed in subgroups of significant predictor variables and simple regression performed to calculate thresholds for adequate IQ. RESULTS: Mean heart rate was 68.2+/-13.3 bpm, mean heart rate variability 11.5+/-16.0 beats per CT-examination (bpct) and median Agatston score 226.5. Average IQ score was 2+/-0.6 whilst diagnostic quality was obtained in 89% of segments. Overall sensitivity, specificity, PPV or NPV was 91.2%, 99.2%, 95.3% or 98.3%. According to multivariate regression, overall IQ was significantly related to heart rate and calcification (P=0.0038; P<0.0001). The effect of heart rate variability was limited to IQ of RCA segments (P=0.018); BMI was not related to IQ (P=0.52). Calcification was the only predictor variable with significant effect on the number of non-diagnostic segments (P<0.0001). In a multivariate regression, calcification was also the single factor with impact on diagnostic accuracy (P=0.0049). CONCLUSION: Whilst heart rate, heart rate variability and calcification all show an inverse correlation to IQ, severe calcium burden remains the single factor with translation of such effect into decrease of diagnostic accuracy.     

Noninvasive coronary angiography with 64-section CT: effect of average heart rate and heart rate variability on image quality

PURPOSE: To evaluate prospectively the effect of average heart rate and heart rate variability on image quality at 64-section computed tomographic (CT) coronary angiography. MATERIALS AND METHODS: The study protocol had local ethics committee approval; written informed consent was obtained. There were 125 patients (45 women, 80 men; mean age, 59.9 years +/- 12.9 [standard deviation]; 79 receiving beta-blockers) who underwent 64-section CT coronary angiography with retrospective electrocardiographic gating. Data sets were reconstructed in 5% steps from 20% to 80% of R-R interval. Heart rate variability was calculated as 1 standard deviation from mean rate during scanning. Two observers rated image quality of each coronary segment at least 1.5-mm diameter (1 = no motion artifacts, 5 = not evaluative). Repeated analysis of variance measurements were performed to evaluate quantitative parameters. Pearson correlation analysis was performed to compare image quality in each patient with average heart rate and heart rate variability. RESULTS: Average heart rate was 63.3 beats per minute +/- 13.1, with variability of 3.2 beats per minute +/- 2.1. Diagnostic image quality (score < or = 3) was attained in 1821 of 1836 segments at the best reconstruction interval. There was no correlation between mean heart rate and image quality for all segments of the right coronary and left anterior descending arteries, but there was a significant correlation for left circumflex artery (r = 0.33, P < .05). Heart rate variability was correlated with image quality overall (r = 0.75, P < .001) and for each coronary artery. Heart rate was less variable and image quality was better (P < .05) in patients receiving beta-blockers. Best image quality was obtained in diastole with heart rate less than 80 beats per minute and in systole with faster heart rate. CONCLUSION: Coronary angiography with 64-section CT provides diagnostic image quality within a wide range of heart rates. Reducing average heart rate and heart rate variability is beneficial for reducing artifacts.     

3D motion adapted gating (3D MAG): a new navigator technique for accelerated acquisition of free breathing navigator gated 3D coronary MR-angiography

This study aimed to evaluate the influence of a new navigator technique (3D MAG) on navigator efficiency, total acquisition time, image quality and diagnostic accuracy. Fifty-six patients with suspected coronary artery disease underwent free breathing navigator gated coronary MRA (Intera, Philips Medical Systems, 1.5 T, spatial resolution 0.9×0.9×3 mm³) with and without 3D MAG. Evaluation of both sequences included: 1) navigator scan efficiency, 2) total acquisition time, 3) assessment of image quality and 4) detection of stenoses >50%. Average navigator efficiencies of the LCA and RCA were 43±12% and 42±12% with and 36±16% and 35±16% without 3D MAG (P<0.01). Scan time was reduced from 12 min 7 s without to 8 min 55 s with 3D MAG for the LCA and from 12 min 19 s to 9 min 7 s with 3D MAG for the RCA (P<0.01). The average scores of image quality of the coronary MRAs with and without 3D MAG were 3.5±0.79 and 3.46±0.84 (P>0.05). There was no significant difference in the sensitivity and specificity in the detection of coronary artery stenoses between coronary MRAs with and without 3D MAG (P>0.05). 3D MAG provides accelerated acquisition of navigator gated coronary MRA by about 19% while maintaining image quality and diagnostic accuracy.     

Three-dimensional coronary MR angiography performed with subject-specific cardiac acquisition windows and motion-adapted respiratory gating

OBJECTIVE: In coronary MR angiography, data are conventionally accepted in only short and fixed periods of the cardiac and respiratory cycles. We hypothesized that a more flexible and subject-specific approach to cardiac and respiratory gating may shorten scanning times while maintaining image quality. SUBJECTS AND METHODS: We implemented an acquisition technique that uses subject-specific acquisition windows in the cardiac cycle and a motion-adapted gating window for respiratory navigator gating. Cardiac acquisition windows and trigger delays were determined individually from a coronary motion scan. Motion-adapted gating used a 2-mm acceptance window for the central 35% of k-space and a 6-mm window for the outer 65% of k-space. In 10 subjects, three-dimensional coronary MR angiograms of the right and left coronary systems were acquired with this technique (the "adaptive technique") as well as a conventional acquisition method, and the scanning times and image quality were compared. The adaptive technique was then applied prospectively to 40 patients who underwent coronary radiographic angiography. RESULTS: Scanning times with the adaptive technique were reduced by a factor of 2.3 for the right coronary artery and by a factor of 2.2 for the left coronary artery system compared with the conventional technique, mainly because we were able to use longer subject-specific acquisition windows in patients with low heart rates. Subjective and objective measurements of image quality showed no significant differences between the two techniques. Prospective evaluation of MR angiograms yielded a sensitivity and specificity of 74.3% and 88.2%, respectively, to detect significant coronary artery stenoses. CONCLUSION: Coronary MR angiography with subject-specific acquisition windows and motion-adapted respiratory gating reduces scanning times while maintaining image quality and provides high diagnostic accuracy for the detection of coronary artery stenosis.     

Coronary artery calcium scoring using ECG-gated multidetector CT: effect of individually optimized image-reconstruction windows on image quality and measurement reproducibility

OBJECTIVE: We studied the effect of using individually optimized image-reconstruction windows on image quality and measurement reproducibility in coronary artery calcium scoring using ECG-gated multidetector CT (MDCT). SUBJECTS AND METHODS: In 50 patients, the coronary arteries were investigated twice with ECG-gated MDCT with 500-msec rotation time. Per scan, three sets of images were reconstructed, respectively, at an image-reconstruction window of 40%, 50%, and 60% of the R-R interval. Image quality was assessed, and the optimal image-reconstruction window per scan and per coronary territory was determined. The interscan variability of calcium mass measurements was calculated for different strategies (use of fixed image-reconstruction window [40%, 50%, or 60%] versus individually optimized image-reconstruction window). RESULTS: A significant improvement in image quality was obtained by selecting the best of three reconstructed data sets (mean image quality score, 4.4 vs 3.7; p < 0.001). Even with individually optimized image-reconstruction window values, we obtained high values for interscan variability (mean +/- SD, 27% +/- 22% vs 31% +/- 35% with a fixed image-reconstruction window). CONCLUSION: The use of individually optimized image-reconstruction windows leads to a significant improvement in image quality. However, interscan variability of calcium mass measurements remains high.     

心室率、心室率波动及心电编辑对心房颤动患者64层螺旋CT冠状动脉成像质量的影响

目的 探讨不同心室率、心室率波动对心房颤动患者64层螺旋CT冠状动脉成像(CTCA)图像质量的影响程度以及心电编辑对图像质量改善的有效性.方法 50例心房颤动患者行CTCA检查.评价心电编辑前后各节段冠状动脉血管的图像质量(优、中、差).用X~2检验分析不同心室率、心室率波动程度间及心电编辑前后图像质量的差异程度,用Pearson方法分析平均心室率及心室率波动程度与图像质量间的相关性.与冠状动脉造影结果进行比较,计算敏感性、特异性、阳性预测值、阴性预测值.结果 50例心房颤动患者,平均心室率47～153次/min,平均(89±23)次/min;心室率波动程度7.7～36.8次/min,平均(18.2±6.1)次/min.共评价冠状动脉血管节段704段,最终不可用于诊断的冠状动脉血管节段24段(3.4%),6例患者(12.0%)的CTCA图像中部分血管段无法满足诊断需要.平均心室率＞100次/min时图像质量差的冠状动脉节段数(11段)及心室率波动程度＞24次/min时图像质量差的冠状动脉节段数(11段)均明显增加(P＜0.05).冠状动脉各节段总体图像质量、右冠状动脉及远段冠状动脉血管图像质量与平均心室率及心室率波动程度均有显著相关性(r值分别为0.50、0.55、0.53、0.49、0.42和0.44,P值均＜0.05).心电编辑前后图像质量间差异有统计学意义(P=0.013).以患者为单位,与冠状动脉造影对照,诊断冠状动脉狭窄≥50%的敏感性、特异性、阴性预测值、阳性预测值分别为100%(6/6)、93.2%(41/44)、100%(41/41)、66.7%(6/9).结论 应用64层螺旋CT进行心房颤动患者的冠状动脉成像检查,可在一定平均心室率及心室率波动范围内通过心电编辑有效改善图像质量,提高检查成功率.     

Image quality and reconstruction intervals of dual-source CT coronary angiography: recommendations for ECG-pulsing windowing

PURPOSE: To evaluate reconstruction intervals and image quality in dual-source computed tomography (DSCT) coronary angiography for optimal placement of the ECG-pulsing window. MATERIALS AND METHODS: DSCT coronary angiography was performed in 60 patients. Thirteen datasets were reconstructed in 5% increments from 20-80%. Two readers independently assessed image quality of each segment in each percentage-interval, using scores ranging from 1 (no motion artifacts) to 4 (nonevaluable). RESULTS: Mean heart rate (HR) was 69.0 +/- 18.9 beats per minute (bpm) (range, 35-117 bpm). Diagnostic image quality (scores 1-3) was found in 97.8% of all segments (763 of 780). The 70% RR-interval provided best image quality in all patients and all HRs. The narrowest reconstruction window providing diagnostic image quality was 60-70% for HR <60 bpm, 60-80% for 60-70 bpm, 55-80% for 70-80 bpm, and 30-80% for HR >80 bpm. CONCLUSIONS: DSCT coronary angiography provides best image quality for various HRs at 70%. The ECG-pulsing window can be adapted according to the HR while maintaining diagnostic image quality.     

3D coronary artery imaging with phase reordering for improved scan efficiency.

Three-dimensional (3D) coronary imaging has the potential to overcome problems resulting from vessel tortuosity and to reduce partial volume effects. With these techniques, however, acquisition times are long and respiratory motion artifacts problematical. This work describes the development of a method that applies phase encode reordering to 3D acquisitions, allowing larger navigator acceptance windows to be used, with a consequent reduction in acquisition time. This method is compared with navigator acceptance window methods (the acceptance-rejection algorithm and the diminishing variance algorithm) and the retrospective respiratory gating technique, both in vitro and in vivo. The use of phase reordering with a 10 mm acceptance window provided a significant increase in scan efficiency over a non-reordered 5 mm method (P<0.001) with no significant change in image quality, and a significant increase in image quality compared with a non-reordered image acquired in the same time (P<0.05). A significant improvement in both image quality and scan efficiency was demonstrated over the retrospective respiratory gating method (P<0.05).     

Prospective-triggered sequential dual-source end-systolic coronary CT angiography for patients with atrial fibrillation: A feasibility study

BackgroundObtaining diagnostic coronary CT angiography with low radiation exposure in patients with irregular heart rhythms such as atrial fibrillation (AF) remains challenging.ObjectiveWe evaluated image quality and inter-reader variability with the use of prospective electrocardiographic (ECG)-triggered sequential dual-source acquisition at end systole for coronary artery disease (CAD) evaluation in patients with AF.MethodsThirty consecutive patients with AF who underwent prospective ECG-triggered sequential dual-source acquisition were evaluated. Images were reconstructed every 50 milliseconds from 250 to 400 milliseconds after the R wave. Two independent, blinded readers evaluated the coronaries for image quality on a 5-point scale (worst to best) and stenosis on 5-point semiquantitative (none to severe) and binary scales (>50% or <50%). Diagnostic image quality was graded for each reconstruction.ResultsEleven patients (37%) had significant (≥50% stenosis) CAD. Average heart rate was 82 ± 20 beats/min and variability range was 71 ± 22 beats/min. Mean effective radiation dose was 6.5 ± 2.4 mSv. Diagnostic image quality was noted in 97.9% of 304 coronary segments with median image quality of 3.0. The 300-millisecond reconstruction phase provided the highest image quality; 70% of patients showed diagnostic image quality. Combination of all phases (250–400 milliseconds) performed significantly better than single or other phase combinations (P < 0.0005 for all comparisons). Inter-reader variability for stenosis detection was excellent, with 98.4% concordance by using a binary scale (50% stenosis cutoff).ConclusionsProspective ECG-triggered sequential dual-source CT acquisition with the use of end-systolic acquisition provides diagnostic image quality with potentially low radiation doses for evaluation of CAD in patients with AF. Use of multiple end-systolic phases over a 150-millisecond window improves diagnostic image quality.     

心电编辑对提高双源CT冠脉图像质量的初步研究

目的:探讨心电编辑在改善双源CT冠脉图像质量中的作用。方法:以冠脉分支为单位,回顾性分析60例心率变异过大或心律失常患者双源CT冠脉成像编辑前后的图像质量,总结不同类型的心电编辑方法。结果:60例心率变异过大或心律失常患者,心率范围为55～269次/min,平均心率(92.8±31.9)次/min,冠脉图像编辑前后的图像质量总评分分别为2.26±1.03、3.5±0.61(t=-17.85,P=0.001);表明编辑前后图像质量的评分有统计学意义,编辑后图像质量明显改善。结论:心电编辑技术可以明显改善心率变异过大或心律失常患者双源CT冠脉成像的图像质量。