Study on motion artifacts in coronary arteries with an anthropomorphic moving heart phantom on an ECG-gated multidetector computed tomography unit

Acquisition time plays a key role in the quality of cardiac multidetector computed tomography (MDCT) and is directly related to the rotation time of the scanner. The purpose of this study is to examine the influence of heart rate and a multisector reconstruction algorithm on the image quality of coronary arteries of an anthropomorphic adjustable moving heart phantom on an ECG-gated MDCT unit. The heart phantom and a coronary artery phantom were used on a MDCT unit with a rotation time of 500 ms. The movement of the heart was determined by analysis of the images taken at different phases. The results indicate that the movement of the coronary arteries on the heart phantom is comparable to that in a clinical setting. The influence of the heart rate on image quality and artifacts was determined by analysis of several heart rates between 40 and 80 bpm where the movement of the heart was synchronized using a retrospective ECG-gated acquisition protocol. The resulting reformatted volume rendering images of the moving heart and the coronary arteries were qualitatively compared as a result of the heart rate. The evaluation was performed on three independent series by two independent radiologists for the image quality of the coronary arteries and the presence of artifacts. The evaluation shows that at heart rates above 50 bpm the influence of motion artifacts in the coronary arteries becomes apparent. In addition the influence of a dedicated multisector reconstruction technique on image quality was determined. The results show that the image quality of the coronary arteries is not only related to the heart rate and that the influence of the multisector reconstruction technique becomes significant above 70 bpm. Therefore, this study proves that from the actual acquisition time per heart cycle one cannot determine an actual acquisition time, but only a mathematical acquisition time.     

64层螺旋CT冠状动脉成像的心率变化及其对图像质量的影响

目的探讨64层螺旋CT冠状动脉成像的心率变化及心率变化对图像质量的影响。方法回顾性分析138例64层螺旋CT冠状动脉成像资料,记录扫描期间的心率变化,根据不同的心率变化分组。A组心率变化0~4次/min,B组心率变化5~9次/min,C组心率变化10~20次/min,D组心率变化>20次/min。比较不同组间的冠状动脉各节段图像质量差异。结果64层螺旋CT冠状动脉成像心率变化在10次/min以内者占89%,RCA1、RCA3、PDA、LMA、LAD、LCX1及LCX2的图像质量A、B、C组间无显著差异(P>0.05),D组与A、B、C组对比图像质量明显下降(P<0.05);RCA2的A、B、C、D组间对比图像质量有显著差异(P<0.05),呈下降趋势。结论64层螺旋CT冠状动脉成像心率变化幅度小,心率变化>20次/min,才引起冠状动脉成像质量明显下降,RCA2段图像质量易受心率波动的影响。     

320排动态容积CT在评价冠状动脉解剖结构方面的价值

目的:探讨320排动态容积CT在评价冠状动脉解剖结构方面的价值,阐述其在CTA扫描方面的优势,并分析其对冠状动脉造影(coronary angiography,CAG)及介入治疗(percutaneous coronary intervention,PCI)的临床指导意义。方法:行320排动态容积扫描的冠状动脉CTA受检者中CTA图像未发现病变且图像质量为1级者70例,均测量其左冠状动脉主干、右冠状动脉、左前降支及左回旋支开口处的内径,左、右冠状动脉的开口位置、开口角度,左前降支与左回旋支之间角度及左主干长度,并按性别分组,行统计学分析。结果:1左冠状动脉主干、右冠状动脉、左前降支及左回旋支开口处的内径平均值分别为(4.10±0.80)mm、(3.52±0.69)mm、(3.43±0.72)mm及(2.84±0.77)mm。其中,男性平均值分别为(4.25±0.80)mm、(3.78±0.68)mm、(3.54±0.75)mm及(3.06±0.83)mm;女性平均值分别为(3.91±0.79)mm、(3.18±0.53)mm、(3.30±0.66)mm及(2.54±0.58)mm。2左、右冠状动脉起始处与升主动脉之间夹角分别为110.13°±15.04°、47.49°±17.19°。其中,男性平均值分别为108.42°±17.25°、45.57°±17.07°;女性平均值分别为112.41°±11.33°、50.05°±17.30°。左前降支与左回旋支之间夹角平均为72.70±30.88°,其中男性为74.18°±31.04°;女性为70.74°±31.08°。3左、右冠状动脉开口位置:位于窦内者分别占78.57%、81.43%,位于窦管结合处者分别占15.71%、14.29%,位于窦外者分别占5.72%、4.29%。4左主干长度平均为(10.49±4.08)mm。其中男性平均为(10.63±4.48)mm;女性平均为(10.29±3.53)mm。5冠状动脉变异情况:左、右冠状动脉开口高位者各1例;双开口10例;右冠状动脉缺如1例;心肌桥9例;冠状动脉瘘1例。结论:320排动态容积CT可清晰显示冠状动脉正常解剖结构及变异情况,对于指导CAG及PCI有重要临床意义。     

Whole-heart steady-state free precession coronary artery magnetic resonance angiography.

Current implementations of coronary artery magnetic resonance angiography (MRA) suffer from limited coverage of the coronary arterial system. Whole-heart coronary MRA was implemented based on a free-breathing steady-state free-precession (SSFP) technique with magnetization preparation. The technique was compared to a similar implementation of conventional, thin-slab coronary MRA in 12 normal volunteers. Three thin-slab volumes were prescribed: 1) a transverse slab, covering the left main (LM) artery and proximal segments of the left anterior ascending (LAD) and left circumflex (LCX) coronary arteries; 2) a double-oblique slab covering the right coronary artery (RCA); and 3) a double-oblique slab covering the proximal and distal segments of the LCX. The whole-heart data set was reformatted in identical orientations. Visible vessel length, vessel sharpness, and vessel diameter were determined and compared separately for each vessel. Whole-heart coronary MRA visualized LM/LAD (11.7 +/- 3.4 cm) and LCX (6.9 +/- 3.6 cm) over a significantly longer distance than the transverse volume (LM/LAD, 6.1 +/- 1.1 cm, P < 0.001; LCX, 4.2 +/- 1.2 cm, P < 0.05). Improvements in visible vessel length for RCA and LCX in the whole-heart approach vs. their respective targeted volumes were not significant. It is concluded that the whole-heart coronary MRA technique improves visible vessel length and facilitates high-quality coronary MRA of the complete coronary artery tree in a single measurement.     

Quantitative parameters to compare image quality of non-invasive coronary angiography with 16-slice, 64-slice and dual-source computed tomography

Multi-slice computed tomography (MSCT) is a non-invasive modality to visualize coronary arteries with an overall good image quality. Improved spatial and temporal resolution of 64-slice and dual-source computed tomography (DSCT) scanners are supposed to have a positive impact on diagnostic accuracy and image quality. However, quantitative parameters to compare image quality of 16-slice, 64-slice MSCT and DSCT are missing. A total of 256 CT examinations were evaluated (Siemens, Sensation 16: n = 90; Siemens Sensation 64: n = 91; Siemens Definition: n = 75). Mean Hounsfield units (HU) were measured in the cavum of the left ventricle (LV), the ascending aorta (Ao), the left ventricular myocardium (My) and the proximal part of the left main (LM), the left anterior descending artery (LAD), the right coronary artery (RCA) and the circumflex artery (CX). Moreover, the ratio of intraluminal attenuation (HU) to myocardial attenuation was assessed for all coronary arteries. Clinical data [body mass index (BMI), gender, heart rate] were accessible for all patients. Mean attenuation (CA) of the coronary arteries was significantly higher for DSCT in comparison to 64- and 16-slice MSCT within the RCA [347 ± 13 vs. 254 ± 14 (64-MSCT) vs. 233 ± 11 (16-MSCT) HU], LM (362 ± 11/275 ± 12/262 ± 9), LAD (332 ± 17/248 ± 19/219 ± 14) and LCX (310 ± 12/210 ± 13/221 ± 10, all p < 0.05), whereas there was no significant difference between DSCT and 64-MSCT for the LV, the Ao and My. Heart rate had a significant impact on CA ratio in 16-slice and 64-slice CT only (p < 0.05). BMI had no impact on the CA ratio in DSCT only (p < 0.001). Improved spatial and temporal resolution of dual-source CT is associated with better opacification of the coronary arteries and a better contrast with the myocardium, which is independent of heart rate. In comparison to MSCT, opacification of the coronary arteries at DSCT is not affected by BMI. The main advantage of DSCT lies with the heart rate independency, which might have a positive impact on the diagnostic accuracy. Christof Burgstahler and Anja Reimann contributed equally to this work     

Flow profiles in the left anterior descending and the right coronary artery assessed by MR velocity quantification: effects of through-plane and in-plane motion of the heart.

PURPOSE: The purpose of this work was to compare the temporal profiles of volume flow in the left anterior descending artery (LAD) and the right coronary artery (RCA) and to assess the effect of through-plane and in-plane myocardial motion. METHOD: In eight healthy volunteers, MR phase-difference velocity quantification was applied with prospective ECG triggering, pixel size of 1.16 x 0.98 mm2 (LAD) or 1.25 x 0.98 mm2 (RCA), velocity sensitivity of 40 cm/s, and data acquisition time window of 64 ms for LAD (3 ky lines per heartbeat) and 24 ms for RCA. In-plane motion was measured from the magnitude images. RESULTS: In the LAD, systolic peak and mean flow values were 0.94+/-0.28 and 0.30 +/-0.22 ml/s, respectively. Diastolic peak and mean flows were 2.42+/-0.56 and 1.38+/-0.43 ml/s. The systolic to diastolic ratio was 0.37+/-0.12 for peak flow and 0.22+/-0.15 for mean flow. Mean flow through the cardiac cycle was 59.1+/-15.0 ml/min. In the RCA, systolic peak and mean flow values were 1.96+/-0.69 and 0.74+/-0.31 ml/s, respectively. Diastolic peak and mean flows were 1.80+/-0.53 and 0.83+/-0.20 ml/s. The systolic to diastolic ratio was 0.97+/-0.58 for peak flow and 0.85+/-0.39 for mean flow. Mean flow through the cardiac cycle was 38.4+/-10.8 ml/min. The in-plane velocity of the coronary artery cross-section was 6.4+/-1.8 cm/s for the LAD and 14.9 +/-4.0 cm/s for the RCA (given by peak values in diastole). CONCLUSION: It is confirmed noninvasively with MR that the LAD shows a predominantly diastolic flow, whereas the RCA shows about equal flow values in systole and diastole. Through-plane motion correction is required for assessing the true flow patterns. The in-plane velocities of the coronary artery cross-sections imply a maximum data acquisition time window, estimated at 58 ms for the LAD and at 23 ms for the RCA.     

变异型心绞痛与冠状动脉病变关系临床分析

目的 :探讨变异型心绞痛与冠状动脉病变的关系。方法 :临床观察 88例VA患者 ,均采用标准 18导联心电图或CM5/CMavF导联系统进行Holter监测 2 4小时 ,并行冠状动脉造影检查 ,明确VA发作时ST段抬高导联的分布特点、与冠状动脉病变的有无、病变范围及程度的关系。结果 :88例患者经冠状动脉造影显示 :冠状动脉狭窄 <5 0 %者占 3 9 8% ,冠状动脉狭窄在 5 0 %～ 10 0 %者占 61 2 %。而冠状动脉造影正常的VA患者发作时痉挛部位在右冠状动脉 (RCA)的占 82 9% ,与在左前降支 (LAD)的占 11 4% ,在左回旋支 (LCX)的占 5 7%比 (P <0 0 0 1) ;存在冠状动脉固定性狭窄的VA患者发作时痉挛部位在LAD的占5 4 7% ,与痉挛部位在RCA的占 2 2 6% ,在LCX的占 2 2 6%比 (P <0 0 1)。结论 :在冠状动脉无明显病变的VA患者中 ,RCA痉挛的发生率明显高于LAD ;而对于存在冠状动脉固定性狭窄的VA患者 ,冠状动脉痉挛的发生率以LAD最高。     

Improvement of image quality with beta-blocker premedication on ECG-gated 16-MDCT coronary angiography

OBJECTIVE: The objective of our study was to assess the effect of beta-blockers on image quality of ECG-gated 16-MDCT coronary angiography. MATERIALS AND METHODS: Coronary CT angiography was performed in two groups: group 1, 24 volunteers (mean age, 50 years; mean heart rate, 69 beats per minute [bpm]; range, 47-97 bpm); and group 2, 15 patients with current ischemic heart disease (mean age, 54 years; mean heart rate, 54 bpm; range, 48-69 bpm) who were premedicated with 20-40 mg of oral propranolol 1 hr before the study. CT scans were obtained on a 16-MDCT scanner with a 12 x 0.75 mm collimation and 420-msec rotation using nonionic contrast material (80 mL; injection rate, 4 ml/sec). Images were reconstructed at 30-80% of the cardiac cycle in increments of 5%. Image quality of the following eight coronary segments was assessed by two radiologists in consensus: left main coronary artery; proximal and middle segments of the left anterior descending (LAD) and left circumflex (LCX) coronary arteries; and the proximal, middle, and distal segments of the right coronary artery (RCA). Image quality was assessed, using a 5-point grading scale, as grades 1-5. Images assessed as grade 4 or 5 were considered to be of diagnostically acceptable quality. RESULTS: In group 1, grade 4 or 5 image quality was achieved for visualization of 92% of the left main coronary arteries; 96% of the proximal LAD coronary arteries; 88% of the middle LAD, proximal LCX, and middle LCX coronary arteries; 83% of the proximal RCAs; 58% of the middle RCAs; and 96% of the distal RCAs. In group 2, this level of image quality was achieved in 100% of the left main coronary arteries, proximal and middle LAD arteries, and proximal LCX arteries; 87% of the middle LCX arteries; and 93% of the proximal, middle, and distal RCAs. CONCLUSION: Reduction of heart rates with beta-blocker premedication improves the image quality of CT coronary angiography, especially in terms of the visualization of the right coronary artery.     

Coronary anomalies assessed by whole‐heart isotropic 3D magnetic resonance imaging for cardiac morphology in congenital heart disease

Purpose

To determine the value of whole‐heart three‐dimensional magnetic resonance imaging (MRI) for coronary artery imaging in children/adolescents with congenital heart disease (CHD).

Materials and Methods

Forty children/adolescents (median age: 14 years, range 2.6–25.8) with CHD underwent free‐breathing navigator‐gated isotropic three‐dimensional steady‐state free‐precession (3D‐SSFP) MRI for cardiac morphology. Two observers independently evaluated visibility of origin, course, vessel lengths, image quality (IQ), and contrast between coronary lumen and myocardium. A subgroup was compared with cardiac catheter.

Results

The total scan time was 6.3 ± 3.2 minutes (mean ± SD, at mean heart rate 76 ± 15/min). The mean vessel length for right coronary artery (RCA) by observer 1 was 97 ± 43 mm (observer 2: 94 ± 37 mm), for left main and anterior descending artery (LM/LAD) 91 ± 40 mm (observer 2: 90 ± 40 mm), and for left circumflex artery (LCX) 64 ± 28mm (observer 2: 66 ± 28 mm). The mean vessel contrast was 0.34 ± 0.05 (range: 0.23–0.45; maximum = 1, minimum = 0). On a 4‐level score (1 = nondiagnostic, 4 = excellent), mean IQ scores ranged between 2.3–2.9 (±0.8–1.0). Both observers agreed on the presence/proximal course of RCA in 40/40, LM/LAD in 38/40, and LCX in 36/40 patients. There was complete agreement with invasive coronary angiography available in 12/40 patients (six anomalies).

Conclusion

Isotropic whole‐heart 3D‐MRI for cardiac morphology allows reliable discrimination between normal and abnormal coronary anatomy in children/adolescents with CHD. J. Magn. Reson. Imaging 2009;29:320–327. © 2009 Wiley‐Liss, Inc.     

16层螺旋CT冠状动脉血管成像技术临床应用

目的:探讨16层螺旋CT冠状动脉成像技术临床应用价值。方法:对45例临床诊断或可疑冠心病的住院患者行16层螺旋CT冠状动脉回顾性心电门控平扫及增强扫描。将增强扫描图像传送到Wizard图像工作站进行最大密度投影(MIP)、多平面重组(MPR)、曲面重组(CPR)、容积再现技术(VRT)及平带多平面重组(RMPR)。并将VRT及MIP重组像为参照,用平扫图像对冠状动脉各支段进行钙化积分。结果:左冠状动脉主干(LM)、左前降支近中段(LAD1、LAD2)、第一对角支(D1)、左回旋支(LCX)及右冠状动脉近段(RCA1)显示均45例(100%),左前降支远段(LAD3)23例(51%),第二对角支(D2)30例(67%),第三对角支(D3)24例(53%),第一左缘支(M1)36例(80%),第二缘支(M2)28例(62%),右冠状动脉中段(RCA2)41例(91%),右冠状动脉远段(RCA3)43例(96%)及后降支(PDA)34例(76%)。左冠状动脉主干钙化12例(27%),左前降支近中段钙化有29例(64%),左回旋支钙化例数22例(49%),右冠状动脉近中段钙化有24例(53%)。结论:16层螺旋CT可对冠状动脉进行钙化积分并准确显影,是冠状动脉粥样硬化疾病筛选和诊断的首选方法。     

Combined thallium 201/technetium 99m-labeled pyrophosphate tomography for identification of the “culprit” vessel in acute myocardial infarction

Background

Many previous investigations have used the presence of transient ischemic ²⁰¹Tl perfusion defect to localize coronary artery stenosis. This study reports the results of ²⁰¹Tl tomography alone and combined ²⁰¹Tl/^99mTc-labeled pyrophosphate (^99mTc PYP) tomography employed to identify the infarct-related vessel in patients with acute myocardial infarction (AMI).

Methods and Results

All short-axis images were evaluated by dividing each left ventricular slice into eight equal sectors. In addition, for combined ²⁰¹Tl/^99mTc PYP tomography, two sectors were added to evaluate involvement of the right ventricle. In a preevaluation phase of the study, the sectors were assigned to the supplying coronary arteries in 75 patients with single chronic myocardial infarction related to the left anterior descending coronary artery (LAD), left circumflex artery (LCX), or right coronary artery (RCA). In this pilot phase, ²⁰¹Tl tomograms were reviewed in conjunction with the angiographic data. This assignment was then tested prospectively in 117 patients with AMI. As confirmed by angiography, the AMI was related to the LAC, LCX, and RCA in 54, 17, and 46 patients, respectively. Sensitivity and specificity for ^99mTc PYP accumulation on combined ²⁰¹Tl/^99mTc PYP tomography were 98% a nd 100% for the LAD, 88% and 99% for the LCX, and 98% and 96% for the RCA, respectively. For ²⁰¹Tl tomography, sensitivity and specificity for identification of the culprit vessel were 94% and 89% for the LAD, 82% and 91% for the LCX, and 72% and 96% for the RCA, respectively.

Conclusion

This prospective study demonstrates that combined ²⁰¹Tl/^99mTc PYP tomography is highly accurate for identification of the infarct-related artery in AMI, even in patients with multivessel disease. Positive contrast visualization of myocardial necrosis in both the left and right ventricle allows for reliable differentiation between AMI related to the LCX or RCA territory. In comparison, for ²⁰¹Tl tomography the sensitivity to detect the culprit vessel, particularly the LCX and RCA, appears to be lower than for ²⁰¹Tl/^99mTc PYP imaging, particularly in patients with prior infarction or right dominant coronary artery.     

256-MSCT对先天性心脏病婴儿心脏成像的冠状动脉检出情况

目的探讨256-MSCT对复杂性先天性心脏病婴儿(1岁内)心脏成像时的冠状动脉检出情况。方法从789例行256-MSCT检查的<1岁的患儿中随机抽取100例,评价冠状动脉节段的成像情况(按10个节段计算),包括检出的节段数目及血管清晰度。结果总节段检出率为51.7%,左主干(LM)及右冠状动脉(RCA)近段检出率分别为96%和99%,左前降支(LAD)、左回旋支(LCX)、RCA各支血管的节段检出率分别为53.33%、33.67%、53.33%。左、右冠状动脉近段血管清晰度评分(4分/3分/2分/1分)分别为LM(62例/22例/12例/4例)和RCA(56例/20例/17例/7例)。患儿平均接受的有效剂量为(0.898±0.282)mSv。结论 256-MSCT对复杂性先天性心脏病婴儿(1岁内)心脏成像时的冠状动脉检出情况较为满意,尤其对左、右冠状动脉近段检出率很高,且血管清晰度明显提高,能够满足临床诊断需求。     

Coronary artery imaging during preoperative CT staging: preliminary experience with 64-slice multidetector CT in 99 consecutive patients

The purpose of this study was to evaluate the clinical feasibility of coronary artery imaging during routine preoperative 64-slice MDCT scans of the chest. Ninety-nine consecutive patients in sinus rhythm underwent a biphasic multidetector-row spiral CT examination of the chest without the administration of beta-blockers, including an ECG-gated acquisition over the cardiac cavities, followed by a non-gated examination of the upper third of the thorax. Data were reconstructed to evaluate coronary arteries and to obtain presurgical staging of the underlying disease. The percentage of assessable segments ranged from 65.4% (972/1,485) when considering all coronary artery segments to 88% (613/693) for the proximal and mid segments, reaching 98% (387/396) for proximal coronary artery segments. The 387 interpretable proximal segments included 97 (97%) LM, 99 (100%) LAD, 96 (97%) LCX and 95 (96%) RCA with a mean attenuation of 280.70±52.93 HU. The mean percentage of assessable segments was significantly higher in patients with a heart rate ≤80 bpm (n=48) than in patients with a heart rate greater than 80 bpm (n=35) (80±11% vs. 72±13%; P=0.0008). Diagnostic image quality was achieved in all patients for preoperative staging of the underlying disorder. The mean estimated effective dose was 12.06±3.25 mSv for ECG-gated scans and 13.88±3.49 mSv for complete chest examinations. Proximal and mid-coronary artery segments can be adequately evaluated during presurgical CT examinations of the chest obtained with 64-slice MDCT without the administration of β-blockers.     

3D radial sampling and 3D affine transform‐based respiratory motion correction technique for free‐breathing whole‐heart coronary MRA with 100% imaging efficiency

The navigator gating and slice tracking approach currently used for respiratory motion compensation during free‐breathing coronary magnetic resonance angiography (MRA) has low imaging efficiency (typically 30–50%), resulting in long imaging times. In this work, a novel respiratory motion correction technique with 100% scan efficiency was developed for free‐breathing whole‐heart coronary MRA. The navigator signal was used as a reference respiratory signal to segment the data into six bins. 3D projection reconstruction k‐space sampling was used for data acquisition and enabled reconstruction of low resolution images within each respiratory bin. The motion between bins was estimated by image registration with a 3D affine transform. The data from the different respiratory bins was retrospectively combined after motion correction to produce the final image. The proposed method was compared with a traditional navigator gating approach in nine healthy subjects. The proposed technique acquired whole‐heart coronary MRA with 1.0 mm³ isotropic spatial resolution in a scan time of 6.8 ± 0.9 min, compared with 16.2 ± 2.8 min for the navigator gating approach. The image quality scores, and length, diameter and sharpness of the right coronary artery (RCA), left anterior descending coronary artery (LAD), and left circumflex coronary artery (LCX) were similar for both approaches (P > 0.05 for all), but the proposed technique reduced scan time by a factor of 2.5. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

Enhanced sensitivity and specificity of thallium-201 imaging for the detection of regional ischemic coronary disease by combining SPECT with "bull's eye" analysis

Previous studies have indicated that the combination of single photon emission computed tomography (SPECT) and quantitative "bull's eye" analysis (QBA) TI-201 cardiac stress imaging may improve the detection of myocardial ischemia over that achieved with planar (PLN) imaging. This study will evaluate the sensitivity and specificity of SPECT and QBA in the detection of disease in the left anterior descending (LAD), left circumflex (LCX), and right coronary artery. Ninety-nine patients who underwent both TI-201 stress imaging and coronary arteriography were evaluated retrospectively. Of the 99, 62 had PLN imaging and 37 were evaluated with SPECT; 23 of these 37 had QBA. The overall sensitivity and specificity were as follows: PLN, 94% and 50%; SPECT, 90% and 67%; QBA, 100% and 20%; and SPECT with QBA, 92% and 72%, respectively. The regional sensitivity and specificity of PLN for individual coronary arteries were as follows: RCA, 78% and 74%; LAD, 89% and 60%; LCX, 50% and 89%, respectively. For SPECT, the results were: RCA, 86% and 93%; LAD, 85% and 88%; and LCX, 60% and 88%. For QBA alone, the results were: RCA, 100% and 75%; LAD, 88% and 53%; and LCX, 100% and 89%. The results for QBA with SPECT were: RCA, 100% and 94%; LAD, 88% and 80%; and LCX, 67% and 95%. Thus, SPECT interpreted on conjunction with QBA showed higher sensitivity for evaluation of ischemia in the RCA and LCX arteries and higher specificity in the detection of LAD and RCA disease than did PLN TI-201 imaging. Because of the low specificity of QBA (20%), caution is advised in the interpretation of QBA alone without reviewing SPECT images.     

Diagnosis of coronary artery disease using thallium imaging: tomographic versus planar imaging

Coronary artery disease was evaluated with tomographic and planar thallium imaging in 31 subjects who had undergone coronary angiography for assessment of chest pain syndrome. Coronary arteriography revealed significant coronary artery disease in 17; and 14 had normal coronary arteries. The sensitivity and specificity for planar imaging was 71% and 79%, and that for tomography, 94% and 79% respectively. The sensitivity and specificity figures for individual coronary artery lesion detection for planar imaging were 87/83 for LAD, 33/100 for LCX and 50/86 for RCA respectively, and for tomography the figures were 87/87 for LAD, 33/95 for LCX and 90/76 for RCA respectively. The use of coronary arteriography as a gold standard was considered by assessing its interobserver variability, which was 16%. The interobserver variability for thallium imaging was 8% and 3% respectively for tomographic and planar acquisitions.     

Comparative localization of myocardial ischemia by exercise electrocardiography and myocardial perfusion SPECT

BACKGROUND: Prior angiographic study has shown that the patterns of ST-segment depression during exercise do not provide localizing information of the responsible coronary lesion. However, little is known regarding the ability of exercise-induced ST-segment displacement to localize myocardial perfusion defects. METHODS AND RESULTS: We studied 552 consecutive patients without prior myocardial infarction who had reversible perfusion defect in one vascular territory on rest 201Tl/exercise 99mTc-labeled sestamibi dual-isotope myocardial perfusion single photon emission computed tomography (SPECT) and ischemic ST depression or elevation during exercise. Of these, 192 patients had angiographically documented coronary artery disease (CAD). Two hundred thirty-two patients had maximal ST depression in anterior leads, 247 patients had maximal ST depression in inferior leads, and 45 patients had similar maximal ST depression in both anterior and inferior leads. Twenty-eight (5%) patients had ST elevation with absent Q waves. In patients with maximal ST depression in anterior leads, perfusion defects were found in the territory of the left anterior descending coronary artery (LAD) in 30%, in the territory of the right coronary artery (RCA) in 52%, and in the territory of the left circumflex coronary artery (LCX) in 18%. In patients with maximal ST depression in inferior leads, perfusion defects were found in RCA territory in 44%, in the LAD territory in 42%, and in the LCX territory in 14%. Compared with exercise ST depression, the less common finding of ST elevation did provide accurate localization of perfusion defects. When ST elevation was greatest in the anterior leads, 96% of patients had LAD territory defects. When ST elevation was most prominent in the inferior leads, 100% patients had RCA territory defects. Data of coronary angiograms demonstrated that myocardial perfusion SPECT correctly identified the most stenotic coronary disease for LAD (94%), LCX (72%), and RCA (75%). CONCLUSIONS: The findings of this study indicate that the site of maximal ST-segment depression does not identify the localization of myocardial perfusion defects. However, the less common finding of exercise-induced ST-segment elevation does predict localization of myocardial ischemia.     

心率对16层螺旋CT冠状动脉造影图像质量的影响

目的探讨心率对16层螺旋CT冠状动脉造影图像质量的影响。方法80例健康体检者行16层螺旋CT回顾性心电门控条件下冠状动脉造影。每位患者的4条冠状动脉分支(左冠状动脉主干、左前降支、左回旋支、右冠状动脉)分别用于图像质量分析。结果心率≤65次/m in有89.3%(100/112支)的图像可用于诊断;心率66~80次/m in有81.1%(198/244支)的图像可用于诊断;心率>80次/m in有64.3%(36/56支)的图像可用于诊断;心律不齐或前后波动>5次/m in有25%(8/32支)的血管可用于诊断。结论MSCTCA图像质量受心率影响,并与之呈负相关。     

含服硝酸甘油对64层螺旋CT冠状动脉成像质量影响的分析

目的 定量评估64层CT在冠状动脉成像中含服和不含服硝酸甘油对冠状动脉显示的差异.方法 分别在相对时段中对含服硝酸甘油(A组)和不含服硝酸甘油(B组)的各100例患者进行64层CT冠状动脉检查,2组受检者均采用回顾性后门控智能mA扫描技术.分别选取左、右冠状动脉的最佳期相进行MPR、MIP、CPR、VR重组.对2组图像分别进行冠状动脉10个测量点管径的测量,并对右冠状动脉、前降支、回旋支3支冠状动脉显示的分支数目进行统计,然后对2组图像管径测量值和分支数目采用完全随机的两样本均数t检验进行统计学比较.结果 右冠状动脉近、中、远段管径A组比B组分别增加0.29、0.17、0.11mm,扩张率分别为8.0%、5.0%、4.0%;前降支分别增加0.40、0.23、0.10 mm,扩张率分别为11.0%、8.0%、4.7%;回旋支分别增加0.42、0.35、0.12 mm,扩张率分别为13.5%、12.5%、5.5%;左主干增加0.31 mm,扩张率7.8%.A组较B组分支数目增加率,右冠状动脉、前降支、回旋支分别为83%、80%、113%.A、B 2组冠状动脉10个血管节段中,右冠状动脉近段、左主干、前降支近、中段、回旋支近、中段差异有统计学意义(t值分别为3.86、3.74、5.35、3.58、5.29、4.64,P值均＜0.01);右冠状动脉中、远段、前降支远段、回旋支远段差异亦有统计学意义(t值分别为2.13、2.58、2.35、2.14,P值均＜0.05).结论 服用硝酸甘油能有效扩张冠状动脉并能有效增加冠状动脉分支的显示,从而提高64层CT冠状动脉成像质量.     

Introduction of an individually optimized protocol for the injection of contrast medium for coronary CT angiography

The aim of this study was to determine whether individually tailored protocols for the injection of contrast medium (CM) result in higher and more homogeneous vascular attenuation throughout the coronary arteries at coronary CT angiography compared with conventional injection protocols using fixed injection parameters. Of 120 patients included in the study, 80 patients were randomized into two groups. Group 1 received 80 mL of CM at 6 mL/s. For group 2 injection parameters were individually adjusted to patient weight, the duration of CT data acquisition, and attenuation parameters following a test bolus. In the control group (group 3) the volume of CM was adjusted to the duration of CT data acquisition and injected at 5 mL/s. Attenuation was measured in the proximal, middle, and distal right coronary artery (RCA), in the proximal and middle left anterior descending artery (LAD), and in cranial and caudal sections of both ventricles. Patient parameters, scan delay, and scan duration did not differ significantly between the groups. Mean CM volume was 82.5 mL (flow rate 5.1 mL/s) in group 2 and 73.5 mL in group 3. Attenuation in both RCA and LAD was significantly higher for group 2 vs. group 3 (RCA: 414.9(±49.9)–396.1(±52.1) HU vs. 366.0(±64.3)–341.6(±72.5) HU; LAD: 398.9(±48.6)–364.6(±44.6) HU vs. 356.3(±69.5)–323.0(±67.2) HU). For group 1 vs. group 2 only attenuation in the distal RCA differed significantly: 396.1(±52.1) vs. 370.7(±70.5) HU. Individually tailored CM injection protocols yield higher attenuation, especially in the distal segments of the coronary vessels, compared with injection protocols using fixed injection parameters.