Coronary 64-slice CT angiography predicts outcome in patients with known or suspected coronary artery disease

The aim of this study was to assess the prognostic value of 64-slice CT angiography (CTA) in patients with known or suspected coronary artery disease (CAD). Sixty-four-slice coronary CTA was performed in 220 patients [mean age 63 ± 11 years, 77 (35%) female] with known or suspected CAD. CTA images were analyzed with regard to the presence and number of coronary lesions. Patients were followed-up for the occurrence of the following clinical endpoints: death, nonfatal myocardial infarction, unstable angina, and coronary revascularization. During a mean follow-up of 14 ± 4 months, 59 patients (27%) reached at least one of the predefined clinical endpoints. Patients with abnormal coronary arteries on CTA (i.e., presence of coronary plaques) had a 1st-year event rate of 34%, whereas in patients with normal coronary arteries no events occurred (event rate, 0%, p < 0.001). Similarly, obstructive lesions (≥50% luminal narrowing) on CTA were associated with a high first-year event rate (59%) compared to patients without stenoses (3%, p < 0.001). The presence of obstructive lesions was a significant independent predictor of an adverse cardiac outcome. Sixty-four-slice CTA predicts cardiac events in patients with known or suspected CAD. Conversely, patients with normal coronary arteries on CTA have an excellent mid-term prognosis.     

64MDCT冠状动脉成像在冠心病诊断中的应用价值

目的探讨64层螺旋CT冠状动脉成像在冠心病诊断中的应用价值。方法随机选择我院2010年10月～2011年12月46例由于胸痛、胸闷就诊的患者,分别给予64层螺旋CT冠状动脉成像与选择性冠状动脉造影,以选择性冠状动脉造影检查的结果为“金标准”,分析64层螺旋CT冠状动脉成像在冠心病诊断中的敏感性、特异性及准确率。结果MDCTCA共检查节段586个,直径在1．5mm以上有504个,检出狭窄程度≥50％的28例,漏诊1例,误诊2例。与冠状动脉造影检查结果相比,64层螺旋CT冠状动脉成像检查的敏感性为96．3％（26／27例）,特异性为89．5％（17／19例）,准确性为93．5％（43／46例）,阳性预测值为92．9％（26／28）,阴性预测值为94．4％（17／18）,差异无统计学意义（P〉0．05）。结论64层螺旋CTCA具有无创、安全、经济且操作简便的优点,对冠状动脉病变诊断具有良好的敏感度和特异性,是一种可广泛应用于冠心病的筛选和诊断的检查方法。     

Value of knowledge-based iterative model reconstruction in low-kV 256-slice coronary CT angiography

BackgroundMost current iterative reconstruction algorithms for CT imaging are a mixture of iterative reconstruction and filtered back projection. The value of “fully” iterative reconstruction in coronary CT angiography remains poorly understood.ObjectiveWe aimed to assess the value of the knowledge-based iterative model reconstruction (IMR) algorithm on the qualitative and quantitative image quality at 256-slice cardiac CT.MethodsWe enrolled 21 patients (mean age: 69 ± 11 years) who underwent retrospectively ECG gated coronary CT anhgiography at 100 kVp tube voltage. Images were reconstructed with the filtered back projection (FBP), hybrid iterative reconstruction (IR), and IMR algorithms. CT attenuation and the contrast-to-noise ratio (CNR) of the coronary arteries were calculated. With the use of a 4-point scale, 2 reviewers visually evaluated the coronary arteries and cardiac structures.ResultsThe mean CT attenuation of the proximal coronary arteries was 369.3 ± 73.6 HU, 363.9 ± 75.3 HU, and 363.3 ± 74.5 HU, respectively, for FBP, hybrid IR, and IMR and was not significantly different. The image noise of the proximal coronary arteries was significantly lower with IMR (11.3 ± 2.8 HU) than FBP (51.9 ± 12.9 HU) and hybrid IR (23.2 ± 5.2 HU). The mean CNR of the proximal coronary arteries was 9.4 ± 2.4, 20.2 ± 4.7, and 41.8 ± 9.5 with FBP, hybrid IR and IMR, respectively; it was significantly higher with IMR. The best subjective image quality for coronary vessels was obtained with IMR (proximal vessels: FBP, 2.6 ± 0.5; hybrid IR, 3.4 ± 0.5; IMR, 3.8 ± 0.4; distal vessels: FBP, 2.3 ± 0.5; hybrid IR. 3.1 ± 0.5; IMR, 3.7 ± 0.5). IMR also yielded the best visualization for cardiac systems, that is myocardium and heart valves.ConclusionThe novel knowledge-based IMR algorithm yields significantly improved CNR and better subjective image quality of coronary vessels and cardiac systems with reliable CT number measurements for cardiac CT imaging.     

Diagnostic value of 64-slice CT angiography in coronary artery disease: a systematic review

PURPOSE: To perform a systematic review of the diagnostic value of 64-multislice CT (MSCT) angiography in the detection of coronary artery disease (CAD) when compared to conventional coronary angiography. MATERIALS AND METHODS: A search of PUBMED and MEDLINE databases for English literature was performed. Only studies with at least 10 patients comparing 64-slice MSCT angiography with conventional coronary angiography in the detection of CAD were included. Diagnostic value of MSCT angiography compared to coronary angiography was compared and analysed at segment-, vessel- and patient-based assessment. RESULTS: Fifteen studies met selection criteria and were included for analysis. Pooled sensitivity, specificity, positive predictive value and negative predictive value as well as 95% confidence interval (CI) were 97% (94 and 99%), 88% (79 and 97%), 94% (91 and 97%), and 95% (90 and 99%) for patient-based assessment; 92% (85 and 99%), 92% (85 and 99%), 78% (66 and 91%) and 98% (96 and 99%) for vessel-based assessment; 90% (85 and 94%), 96% (95 and 97%), 75%(68 and 82%) and 98% (98 and 99%) for segment-based assessment, respectively. No significant difference was found in the diagnostic accuracy of 64-slice CT in the detection of CAD when comparison was performed either among four main coronary arteries, or between proximal and middle or distal segments (p>0.05). CONCLUSION: Our results showed that 64-slice CT angiography has a high-diagnostic value in the detection of CAD. Severe coronary artery calcification seems to be the major factor affecting the visualisation and assessment.     

64层CT冠状动脉造影和磁共振多技术扫描联合诊断冠心病

目的：探讨64层螺旋CT冠状动脉造影（CTA）和磁共振心脏多技术扫描联合诊断冠心病（CHD）的临床应用价值。材料和方法：28例拟行冠状动脉造影（CAG）的冠心病患者，于术前1周分别完成64层螺旋CTA及磁共振心脏多技术扫描，以CAG为标准分析CTA与MRI诊断冠心病的各项指标，评价平行试验和系列试验的诊断价值。结果：64层螺旋CTA判断中、重度狭窄血管（≥50％）的敏感度、特异度、准确度、阳性预测值、阴性预测值为87．88％、98．73％、95．54％、96．67％、95．12％。磁共振多技术扫描左室增大8例，室壁明显变薄7例。在476个节段中，29个节段（6．09％）运动减弱或不运动，9个节段（1．89％）出现矛盾运动或室壁瘤。左心功能改变，与正常值相比有统计学意义（P〈0．001）。MRI间接推断中、重度狭窄血管（≥50％）的敏感度、特异度、准确度、阳性预测值、阴性预测值为93．75％、86．54％、89．29％、81．08％、95．74％。两种方法联合平行试验和系列试验总的敏感度、特异度分别为99．24％、85．44％，82．39％、99．83％。结论：64层螺旋CTA和磁共振心脏多技术扫描诊断冠心病各有优势，两者互相补充，联合使用可方便、全面、准确、无创地对冠心病患者进行评估。     

64层螺旋CT冠状动脉成像与冠状动脉造影的对比研究

目的评价64层螺旋CT冠状动脉成像诊断冠状动脉狭窄的准确性。方法 50例患者先后进行64层螺旋CT冠状动脉成像和冠状动脉造影检查,以冠状动脉造影为诊断冠状动脉疾病的"金标准",比较CT冠状动脉成像的符合率,评价64层螺旋CT冠状动脉成像诊断冠心病的准确性。结果 64层螺旋CT冠状动脉成像评价冠状动脉狭窄程度大于或等于50%的敏感性为98.6%,诊断狭窄程度小于50%的敏感性为87.0%,诊断冠状动脉狭窄的特异性为92.5%,阴性预测值为97.7%。结论 64层螺旋CT冠脉成像诊断冠状动脉狭窄有很高的准确率。     

64层螺旋CT对低龄儿童川崎病冠状动脉成像质量的探讨

目的 探讨64层螺旋CT对随访中低年龄儿童川崎病冠状动脉瘤的冠状动脉成像质量技术,并对图像进行评估分析. 资料与方法 应用64层螺旋CT对12例随访中川崎病冠状动脉瘤的男性儿童(平均年龄5.1岁,随访时间1.1～5.1年)进行回顾性心电门控技术冠状动脉成像,在无屏气状态下进行扫描,扫描时平均心率(74±12)次/min;采用"去条带状伪影"的心脏重组算法进行血管分析处理.由两名影像科医师独立对成像重组时相、每例患者的冠状动脉13个节段进行直径测量和图像质量评估,并观察冠状动脉瘤的数目、位置、形态和大小. 结果 共有114/156个节段能满足图像评价并进行直径测量,符合诊断要求率达到73%;两侧冠状动脉最佳显示相位窗集中在45%和75%～85%两个相位区间.MSCT共观察到30个冠状动脉瘤,其中8个较小或位于中远段的冠状动脉瘤超声心动图未能发现. 结论 在较高心率、无屏气扫描模式下,选择适当的对比剂剂量和流率、准确的扫描时间、合适的重组相位和有效心脏重组算法的64层螺旋CT冠状动脉成像技术,可以成为低年龄川崎病冠状动脉瘤患儿随访和诊断的重要评估方法.     

A method for calcium quantification by means of CT coronary angiography using 64-multidetector CT: very high correlation with agatston and volume scores

To find out whether calcium scoring of the coronary arteries (CAC scoring) could be carried out with a CT angiography of the coronary arteries (CTCA) in a single CT data acquisition. The Agatston and V130 scores for 113 patients were assessed. A calcium volume score (V600 score) was compiled from the CTCA data sets. Intra- and interobserver correlations were excellent (ρ > 0.97). The intra- and interobserver repeatability coefficients were extremely low, increasing in magnitude from the V600 score to the V130 and Agatston scores. The V600 score underestimates the coronary calcium burden. However, it has a linear relation to the Agatston and V130 scores. Thus, they are predictable from the values of the V600 score. The V600 score shows a linear relation to the classic CAC scores. Due to its extremely high reliability, the score may be a feasible alternative for classic CAC scoring methods in order to reduce radiation dosages.     

Optimal scanning protocols of 64-slice CT angiography in coronary artery stents: An in vitro phantom study

Purpose

The purpose of the study was to investigate the optimal scanning protocol of 64-slice CT angiography for assessment of coronary artery stents based on a phantom study.

Materials and methods

Coronary stents with a diameter of 2.5 mm was implanted in thin plastic tubes with an inner diameter of 3.0 mm to simulate a coronary artery. The tubes were filled with iodinated contrast medium diluted to 178 HU, closed at both ends and positioned in a plastic container filled with vegetable oil (−70 to −100 HU). A series of scans were performed with a 64-slice CT scanner with the following protocols: section thickness: 0.67 mm, 1.0 mm, 1.5 mm, 2.0 mm, pitch value: 0.2, 0.3, 0.5 and reconstruction interval of 50% overlap of the section thickness. 2D axial and multiplanar reformatted images were generated to assess the visibility of stent lumen, while virtual intravascular endoscopy (VIE) was reconstructed to evaluate the artery wall and stent surface.

Results

Our results showed that a scanning protocol of 1.0 mm slice thickness with a pitch of 0.3 produced acceptable images with best demonstration of the intrastent lumen and stent surface with minimal image noise or artifacts. In contrast, submillimeter scans with 0.67 mm resulted in moderate artifacts which affected visualization of the coronary lumen, in addition to the increased noise. When the section thickness increased to 1.5 mm and 2.0 mm, visualization of the artery wall and stent surface was compromised, although the intrastent lumen was still visible.

Conclusion

Our in vitro study suggested that a scanning protocol of 1.0 mm section thickness with pitch of 0.3 is the optimal protocol for evaluation of coronary artery stents as it allows generation of acceptable images with better visualization of stent lumen, stent surface and coronary artery wall.     

64MSCTA对冠状动脉变异的诊断及临床评价

目的评价64层螺旋CT冠状动脉血管成像（CTCA）对冠状动脉变异的诊断价值及临床评价。方法回顾性分析3529例临床疑为心肌缺血患者及常规体查者冠状动脉CTA影像检查结果并对发现的变异冠状动脉进行分类。结果3529例冠状动脉CTA受检者中,共检出冠状动脉变异42例（1．19％,42／3529）,MIP、VRT、CPR重建图像均明确显示其开口及走行;其中右冠状动脉起自主动脉左冠状窦者9例,左冠状动脉起自主动脉右冠状窦者2例,左回旋支异位开口于右冠窦1例,冠状动脉高位开口于升主动脉壁者6例．并行左主干3例（前降支、旋支分别开口于左冠窦）,左主干开口于肺动脉伴右冠状动脉瘤1例,左旋支-冠状静脉瘘者2例,副冠状动脉9例,右冠状动脉-左心室瘘合并右冠状动脉瘤l例。冠状动脉发育不良8例。结论冠状动脉CTA能准确显示各种类型冠状动脉变异,可作为无创性诊断冠状动脉变异的首选方法。     

64排螺旋CT冠状动脉血管成像诊断冠状动脉-肺动脉瘘的应用价值

目的 评价64排螺旋CT三维重组技术诊断冠状动脉-肺动脉瘘(CPF)的应用价值。 方法 回顾性分析20例行64排螺旋CT冠状动脉血管成像的CPF患者的资料, 其图像行容积再现、多平面重组、曲面重组、最大密度投影, 分析CPF的检出率、异常血管的CT特征及多排螺旋CT的诊断意义。 结果 CPF血管起源:左冠状动脉分支或左圆锥支11例, 左冠状动脉分支及右圆锥支(或左右圆锥支)7例, 右圆锥支1例, 双侧冠状动脉多分支1例。异常血管形态:迂曲扩张血管网19例, 单纯扩张血管1例, 匍匐于肺动脉壁20例; 合并囊状动脉瘤5例, 梭形动脉瘤1例。肺动脉瘘口的位置:主肺动脉左侧壁14例, 左前壁1例, 前壁2例, 左侧壁和前壁1例, 左前壁和右侧壁1例, 未见明确瘘口1例。瘘口的CT特征:开窗征17例, 射血征8例, 烟雾征3例, 飘带征1例, 等密度征10例。 结论 多排螺旋CT重组技术可清晰显示CPF的异常血管及瘘口特征, 为临床诊治提供重要信息, 可作为诊断的首选方法。     

Accuracy of 64-slice CT angiography for the detection of functionally relevant coronary stenoses as assessed with myocardial perfusion SPECT

Purpose CT angiography (CTA) offers a valuable alternative for the diagnosis of CAD but its value in the detection of functionally relevant coronary stenoses remains uncertain. We prospectively compared the accuracy of 64-slice CTA with that of myocardial perfusion imaging (MPI) using ^99mTc-tetrofosmin-SPECT as the gold standard for the detection of functionally relevant coronary artery disease (CAD). Methods MPI and 64-slice CT were performed in 100 consecutive patients. CTA lesions were analysed quantitatively and area stenoses ≥50% and ≥75% were compared with the MPI findings. Results In 23 patients, MPI perfusion defects were found (12 reversible, 13 fixed). A total of 399 coronary arteries and 1,386 segments was analysed. Eighty-four segments (6.1%) in 23 coronary arteries (5.8%) of nine patients (9.0%) were excluded owing to insufficient image quality. In the remaining 1,302 segments, quantitative CTA revealed stenoses ≥50% in 57 of 376 coronary arteries (15.2%) and stenoses ≥75% in 32 (8.5%) coronary arteries. Using a cut-off at ≥75% area stenosis, CTA yielded the following sensitivity, specificity, negative (NPV) and positive predictive value (PPV), and accuracy for the detection of any (fixed and reversible) MPI defect: by patient, 75%, 90%, 93%, 68% and 87%, respectively; by artery, 76%, 95%, 99%, 50% and 94%, respectively. Conclusion Sixty-four-slice CTA is a reliable tool to rule out functionally relevant CAD in a non-selected population with an intermediate pretest likelihood of disease. However, an abnormal CTA is a poor predictor of ischaemia.     

Diagnostic value of 64-slice multi-detector row cardiac CTA in symptomatic patients

Cardiac multi-detector-row computed tomography (MDCT) angiography has shown high levels of sensitivity and especially negative predictive value regarding the diagnosis of coronary artery disease (CAD). This study was designed to determine the value of a 64-slice-MDCT scanner in comparison to invasive coronary angiography for the detection of CAD in a population of symptomatic patients. Fifty-one patients with suspected CAD underwent conventional coronary angiography and ECG-gated cardiac 64-slice-MDCT angiography with a rotation time of 330 ms, a collimation of 64×0.6 mm and a slice thickness of 0.75 mm. Blinded patient- and segment-based analysis was performed for the detection of stenoses ≥70% of the vessel lumen. 95% of all coronary segments were assessable by MDCT angiography. Patient-based (segment-based) analysis revealed a sensitivity of 97.8% (86.7%), specificity of 50% (95.2%), positive predictive value of 93.6% (75.2%) and negative predictive value of 75% (97.7%). Inter-rater agreement revealed a kappa-value of 0.558 (0.722). In this symptomatic patient group a 64-slice-MDCT scanner shows good agreement on a segment-based analysis but only moderate agreement on a patient-based analysis. The diagnostic accuracy of 64-slice-MDCT coronary angiography is negatively influenced by the high pre-test probability of this symptomatic patient collective.     

双源CT诊断冠脉狭窄的价值—与冠状动脉造影对照分析

目的:探讨双源CT冠脉成像评价冠脉中度及中度以上狭窄的准确性及可行性。方法:入选60例临床高度怀疑或已确诊冠脉疾病的患者,行双源CT扫描,扫描过程中患者心率平稳,未出现心率不齐及心律失常。患者于1周内行经皮选择性冠状动脉造影,并以冠状动脉造影作为标准,从冠脉节段及冠脉分支角度分别评价双源CT诊断冠脉中度及中度以上狭窄的准确性、敏感性、特异性、阳性预测率及阴性预测率。结果:以冠脉节段为基础分析,双源CT诊断冠脉明显狭窄的敏感性、特异性、阳性预测率、阴性预测率、准确性分别为81.14%、97.57%、85.34%、96.74%、95.13%;以冠脉分支为基础分析,双源CT诊断冠脉明显狭窄的敏感性、特异性、阳性预测率、阴性预测率、准确性分别为84.21%、93.79%、89.88%、90.06%、90.0%。双源CT与选择性冠脉造影对发现冠脉狭窄节段及检查冠脉分支病变的能力进行卡方检验,χ2分别0.625、1.041;P0.05,双源CT与选择性冠脉造影比较在发现冠脉明显狭窄差异上无统计学意义。结论:双源CT在诊断冠脉明显狭窄时有很高的准确性,可作为无创性评价冠脉狭窄及疾病的手段。     

64排螺旋CT冠状动脉成像的前瞻性与回顾性心电门控技术的图像质量及辐射剂量的比较研究

目的 研究前瞻性心电门控触发(prospective ECG-triggering)与回顾性心电门控(retrospective ECG gating)两种技术方法行冠状动脉CTA检查时,对冠状动脉图像质量及辐射剂量的比较。方法 33名疑似冠状动脉疾病的患者分两组进行对比研究。前瞻组16例为前瞻性心电门控成像,心率小于65次/min;回顾组17例为回顾性心电门控成像,心率小于75次/min。记录两组的辐射剂量并统计分析,同时进行图像质量评价。结果 两组图像质量比较,差异无统计学意义(P＞0.05)。前瞻性心电门控冠状动脉CTA的平均DLP 234.4mGy·cm,占回顾性心电门控冠状动脉CTA的平均DLP974.4mGy·cm的24.1%。前瞻性心电门控冠状动脉CTA的患者的平均有效剂量为3.2mSv,回顾心电门控冠状动脉CTA患者的为13.6mSv,降低76.47%。结论 64排螺旋CT在前瞻性心电门控冠状动脉CTA与回顾性心电门控冠状动脉CTA比较可以获得相似的图像质量,可大幅降低患者的有效剂量对于不能接受高辐射剂量且心率较低的受检人群具有重要的临床价值。     

The value of Coronary Artery computed Tomography as the first-line anatomical test for stable patients with indications for invasive angiography due to suspected Coronary Artery Disease: CAT-CAD randomized trial

BackgroundThe aim of this prospective, randomized trial was to evaluate whether the use of coronary computed tomography angiography (CCTA) as the first-line anatomical test in patients with suspected significant coronary artery disease (CAD) may reduce the number of coronary invasive angiographies (ICA), and expand the use of CCTA in patients currently diagnosed invasively.Methods120 patients (age:60.6 ± 7.9 years, 35% female) with indications to ICA were randomized 1:1 to undergo CCTA versus direct ICA. Outcomes were evaluated during the diagnostic and therapeutic periods.ResultsThe number of invasively examined patients was reduced by 64.4% in the CCTA group as compared to the direct ICA group (21vs59,p < 0.0001). The number of patients with ICAs not followed by coronary intervention was reduced by 88.1% with the CCTA strategy (5vs42,p < 0.0001). Over the diagnostic and therapeutic course there were no significant differences regarding the median volume of contrast (CCTA 80.3 ml[65.0–165.0] vs ICA 90.0 ml[55.0–100.0], p = 0.099), while a non-significant trend towards higher radiation dose in the CCTA group was observed (9.9 mSv[7.0–22.1] vs 9.4 mSv[5.2–14.0], p = 0.05). There were no acute cardiovascular events.ConclusionsCCTA may hypothetically act as an effective ‘gatekeeper’ to the catheterization laboratory in the diagnosis of stable patients with current indications for ICA. This strategy may result in non-invasive, outpatient-based triage of two thirds of individuals without actionable CAD, obviating unnecessary invasive examinations. However, the longer follow-up is indispensable.ClinicalTrials.gov numberNCT02591992     

2型糖尿病患者64层螺旋CT冠状动脉造影表现的研究

目的:评价64层螺旋CT冠状动脉造影检测2型糖尿病患者冠脉病变程度、冠脉内斑块性质的价值;评估2型糖尿病患者冠状动脉病变发生的危险性。方法:收集200例患者(糖尿病组100例,非糖尿病组100例)64层螺旋CT冠状动脉成像资料,并根据糖尿病患者发病年限将2型糖尿病组分成3组:0~6年、6~14年、>14年,对冠状动脉狭窄程度及斑块性质进行评价。结果:2型糖尿病组血管病变支数明显多于非2型糖尿病组(P<0.01),2型糖尿病组单支病变明显少于非糖尿病组(P<0.05);糖尿病组三支病变发生率为36.9%,而非糖尿病组发生率为33.5%,两组比较差异有统计学意义(P<0.05)。2型糖尿病组重度狭窄病变明显多于非糖尿病组(P<0.05)。研究显示:0~6年组冠脉病变以纤维斑块为主,管腔以轻中、度狭窄为主;6~14年组病变以纤维斑块和混合斑块为主,管腔呈中、重度狭窄;>14年组病变以弥漫钙化为主,管腔呈中、重度狭窄。Logistic分析表明2型糖尿病与冠状动脉病变密切相关。结论:2型糖尿病患者有高度的冠状动脉病变危险性,且随患病年限延长病变加重。64层螺旋CT是糖尿病患者诊断冠状动脉病变可靠的、无创的检查方法,可有效检测糖尿病患者冠状动脉病变的程度和冠脉斑块性质,对冠心病诊断和临床评估冠心病风险具有重要价值。     

高血糖合并隐匿性冠心病患者的冠状动脉CT血管成像研究

目的在2型糖尿病(DM)及糖调节受损(IGR)隐匿性冠心病患者中进行64层CT冠状动脉成像研究,明确64层CT对高血糖合并隐匿性冠心病患者冠状动脉病变的诊断价值。方法选取2009年4月至2011年6月山西省人民医院内分泌科门诊及住院患者120例,包括DM53例和IGR 67例,所有患者均完成一般体格检查、血糖、血脂、血压及64层CT冠状动脉成像检查。血管阻塞面积大于等于50%者推荐行冠状动脉腔内成形(PCI)术。结果所有患者中38例(31.7%)存在显著的冠状动脉狭窄,其中DM患者25例(47.2%),IGR患者13例(19.4%),二者之间存在显著差异(P<0.01)。DM者较IGR者不仅冠脉狭窄、钙化斑块的发生率显著升高(50.8%vs 27.4%,P<0.05),而且发生多支病变者也显著增多,但二者间软斑块的发生率无显著性差异。结论 64层CT冠状动脉成像检查作为一项无创的检查方法,不仅能够有效分辨冠状动脉硬化的程度,而且能够区分斑块的类型,对于指导DM及IGR合并隐匿性冠心病患者下一步进行冠心病阻断治疗或进行冠脉血运重建具有重要意义。     

Effect of dose-reduced scan protocols on cardiac coronary image quality with 64-row MDCT: a cardiac phantom study

OBJECTIVE: To evaluate the feasibility of using relative low-dose scan protocols in coronary imaging with 64-row MDCT. MATERIALS AND METHODS: A pulsating cardiac phantom was used to simulate coronary arteries of two sizes (3 and 5mm in diameter) with three stenosis degrees (25, 50 and 75%) at 55bpm heart rate. Cardiac scans were performed on a 64-row MDCT scanner (GE LightSpeed VCT) with rotation time of 350ms and pitch of 0.2 under six different scan protocols: 120kV/650mA, 1137.5mAs (effective) (CTDI(vol) 121.69mGy), 120kV/550mA, 962.5mAs (CTDI(vol) 102.96mGy), 120kV/450mA, 787.5mAs (CTDI(vol) 84.24mGy), 120kV/350mA, 612.5mAs (CTDI(vol) 65.52mGy), 100kV/590mA, 1032.5mAs (CTDI(vol) 65.17mGy) and 140kV/390mA, 682.5mAs (CTDI(vol) 102.22mGy). The simulative coronary arteries were filled with contrast media to reach 300HU in the lumen. Background noise was measured to describe the basic image quality accordingly. CNR, SNR and contour sharpness represented in slope of CT density curve was calculated as well. Measured stenosis area and rates, described by the percentage area of stenosis on the cross-section images were also calculated. RESULTS: The corresponding image noise levels described in standard deviation of background signals varied with radiation dose, CNR and SNR mainly varied with tube current. The contour sharpness, which can reflect actual spatial resolution, is affected mainly by tube voltage. The first five protocols depicted obviously steeper curves than the sixth one (P<0.05). As for 25% stenosis, there was no significant difference among the stenosis rates of the six protocols (P>0.05). As for evaluation on 50 and 75% stenosis, there was no significant difference between the first two protocols, and between the second two protocols as well. However, significant difference presented between these two groups (P>0.05). When comparing the groups with similar radiation dose, protocols with lower tube voltage gain more accuracy in representing stenosis area and rate. CONCLUSION: Dose level and corresponding image quality is relevant to the accuracy of stenosis evaluation on simulated coronary arteries with 64-row MDCT. In this study, we find relative low-dose protocols with acceptable image quality showed a tendency of overestimating stenosis. Furthermore, using a lower tube voltage and higher tube current to gain accurate imaging result is more applicable than other protocols with the same radiation dose level.