Coronary artery stenoses: a phantom study using contrast enhanced three-dimensional electron beam tomography

This paper evaluated the accuracy of electron beam tomographic angiography (EBA) with conventional coronary arteriography (CCA) using four graded artificial stenoses in a postmortem swine coronary phantom model. The sensitivity, specificity, and accuracy of EBA for diagnosing significant stenosis (> or =50% stenosis) were 94.3%, 96.7%, and 95.8%, respectively. The diagnostic accuracy of EBA had no significant difference with CCA (chi(2)=0.0162; P>.05). EBA three-dimensional (3D) procedures had high interobserver reproducibility (k=.92-.95, P>.05). Maximum intensity projection (MIP) was the most sensitive and curved planar reformation (CPR) was the most accurate 3D procedure for quantitatively identifying coronary stenosis. EBA yields promising results concerning the visualization of coronary artery stenosis with high accuracy for stenoses >50%.     

Coronary artery calcium: absolute quantification in nonenhanced and contrast-enhanced multi-detector row CT studies

PURPOSE: (a) To determine the accuracy of multi-detector row computed tomography (CT) in the measurement of the calcium concentration in a cardiac CT calibration phantom and (b) to assess the correlation of a traditional 3-mm section width CT coronary screening protocol and a 1.25-mm section width CT angiography imaging protocol in the quantification of the absolute mass of coronary calcium in patients who underwent both coronary screening and CT angiography with a multi-detector row CT scanner. MATERIALS AND METHODS: A heart phantom containing calcified cylinders was scanned to determine calibration factors and absolute calcium mass. In 50 patients, the variability (value 1 - value 2/mean value 1 - value 2), limit of agreement (+/-2SD value 1 - value 2), and systematic error (mean value 1 - value 2) of the total amount of coronary calcium calculated at traditional 3-mm section width CT and at 1.25-mm section width CT angiography were determined. RESULTS: The correlation coefficient between the 3-mm section width, nonenhanced protocol and the 1.25-mm section width CT angiography protocol was very high (r = 0.977) and the mean variability was low (19.7%) for the absolute mass. There was a systematic error of -6.7 mg and a limit of agreement between 45.0 mg and -58.5 mg. CONCLUSION: Use of the mass quantification algorithm in combination with a calibration phantom allows accurate quantification of coronary calcium. Measurements of calcium mass obtained at 1.25-mm section width CT angiography have the best agreement with those obtained at the traditional 3-mm section width imaging protocol.     

Coronary pressure-derived fractional flow reserve in the assessment of coronary artery stenoses

Objectives

Catheter-based angiography is the reference-standard to establish coronary anatomy. While routinely employed clinically, lumen assessment correlates poorly with physiological measures of ischaemia. Moreover, functional studies to identify and localise ischaemia before elective angiography are often not available. This article reviews fractional flow reserve (FFR) and its role in guiding patient management for patients with a potentially haemodynamic significant coronary lesion.

Methods

This review discusses the theory, evidence, indications, and limitations of FFR. Also included are emerging non-invasive imaging FFR surrogates currently under evaluation for accuracy with respect to standard FFR.

Results

Coronary pressure-derived fractional flow reserve (FFR) rapidly assesses the haemodynamic significance of individual coronary artery lesions and can readily be performed in the catheterisation laboratory. The use of FFR has been shown to effectively guide coronary revascularization procedures leading to improved patient outcomes.

Conclusions

FFR is an invaluable modality in guiding coronary disease treatment decisions. It is safe, cost-effective and leads to improved patient outcomes. Non-invasive imaging modalities to assess the physiologic significance of CAD are currently being? developed and evaluated.

Key points

? Coronary pressure-derived fractional flow reserve (FFR) is an important adjunct to angiography. ? FFR is an invaluable technique in guiding coronary disease treatment decisions. ? FFR is safe, cost-effective and leads to improved patient outcomes. ? New directions include CT-based non-invasive conventional FFR surrogates for functional lesion significance.     

定量CT灌注无创性评估功能相关冠状动脉狭窄:初步临床经验

目的研发了一种定量动态对比增强CT(DCE-CT)技术为测量心肌灌注贮备量和心肌容积贮备量,并研究它们与冠状动脉狭窄的关系。方法 26例有冠状动脉疾病的病人入组,冠状动脉狭窄的分度是依据血管造影,分为无狭窄(血     

Non-invasive assessment of functionally relevant coronary artery stenoses with quantitative CT perfusion: preliminary clinical experiences

Objectives

We developed a quantitative Dynamic Contrast-Enhanced CT (DCE-CT) technique for measuring Myocardial Perfusion Reserve (MPR) and Volume Reserve (MVR) and studied their relationship with coronary stenosis.

Methods

Twenty-six patients with Coronary Artery Disease (CAD) were recruited. Degree of stenosis in each coronary artery was classified from catheter-based angiograms as Non-Stenosed (NS, angiographically normal or mildly irregular), Moderately Stenosed (MS, 50?C80% reduction in luminal diameter), Severely Stenosed (SS, >80%) and SS with Collaterals (SSC). DCE-CT at rest and after dipyridamole infusion was performed using 64-slice CT. Mid-diastolic heart images were corrected for beam hardening and analyzed using proprietary software to calculate Myocardial Blood Flow (MBF, in mL?min^-1?100?g^-1) and Blood Volume (MBV, in mL?100?g^-1) parametric maps. MPR and MVR in each coronary territory were calculated by dividing MBF and MBV after pharmacological stress by their respective baseline values.

Results

MPR and MVR in MS and SS territories were significantly lower than those of NS territories (p?Conclusions DCE-CT imaging with quantitative CT perfusion analysis could be useful for detecting coronary stenoses that are functionally significant.

Key Points

? A new quantitative CT technique for measuring myocardial function has been developed ? This new technique provides data about myocardial perfusion and volume reserve ? It demonstrates the important relationship between myocardial reserve and coronary stenosis. ? This single test can identify which coronary stenoses are functionally significant     

Coronary artery calcium measurement: agreement of multirow detector and electron beam CT

OBJECTIVE: The purpose of our study was to establish the most suitable algorithm to compare coronary artery calcium measurements performed with electron beam CT and multirow detector CT for the assessment of coronary artery disease. SUBJECTS AND METHODS: Coronary artery screening was performed in 100 patients with both electron beam and multirow detector CT. The images were transferred to a dedicated workstation for determination of the calcium score, volume, mass, density, and number of lesions. In addition to the traditional threshold of 130 H, the score of multirow detector CT studies was reevaluated at a threshold of 90 H. Fifty-nine of the patients underwent conventional coronary catheterization. Receiver operating characteristic curve analysis of the different scoring algorithms for detection of significant coronary artery stenosis was performed. RESULTS: The correlation between electron beam CT and multirow detector CT was high for every quantification algorithm. Determination of the score and the number of lesions with multirow detector CT revealed a systematic error of the measurement compared with electron beam CT. The areas under the curve in the receiver operating characteristic curve analyses for electron beam and multirow detector CT were similar for the score, volume, and mass, whereas they were lower for the density. No significant difference was found for the areas under the curve between scores using a 130-H and those using a 90-H threshold. CONCLUSION: Volume and mass indexes are superior to the traditional score, density, and number of lesions for comparing the results of electron beam and multirow detector CT and for determining significant coronary artery disease.     

Coronary artery stent imaging with CT using an integrated electronics detector and iterative reconstructions: First in vitro experience

BackgroundDespite continuous improvements in CT technology, accurate stent lumen delineation remains challenging.PurposeThe aim was to evaluate the quality of coronary stent lumen delineation with CT using a detector with integrated electronics.MethodsTwelve coronary stents placed in plastic tubes and filled with contrast agent (CT number 250 HU) were imaged with either a 128-section dual-source CT machine equipped with conventional detector or with integrated electronics. On both scanners, images were reconstructed with filtered back projection (slice thickness 0.6 mm; increment 0.4 mm) and sinogram-affirmed iterative reconstruction (slice thickness 0.6 mm; increment 0.4 mm), and with iterative reconstruction (slice thickness 0.5 mm; increment 0.3 mm) on the integrated scanner. Two blinded, independent readers assessed image quality, noise, in-stent diameter, in-stent attenuation, and image sharpness by using signal intensity profiles across stents.ResultsInterreader agreement for image quality assessment was substantial (κ = 0.798). Both readers rated best image quality in data sets from integrated detector at highest spatial resolution (86 or 72% of stents rated best quality). Image noise was significantly lower in data sets scanned with integrated detector, being lowest at 0.6 mm slice thickness (14.3 vs 21.0 HU; P < .001). Differences between measured and true in-stent diameters and differences in attenuation across stents were smallest, and average/maximum image sharpness was highest in data sets from the integrated detector using iterative reconstructions.ConclusionCT coronary stent imaging is significantly improved by using a detector with integrated electronics combined with iterative reconstructions.     

Detection of coronary artery stenoses with multislice helical CT angiography

OBJECTIVES: The authors compared multislice CT angiography and selective angiography for the assessment of coronary artery disease. METHODS: In 28 patients, the presence and degree of coronary artery stenoses were determined in coronary segments prepared with beta-blocker for good image quality with multislice CT. RESULTS: In 187 coronary artery segments, sensitivity, specificity, and negative predictive value for the detection of stenoses >50% with multislice CT angiography were 81%, 90%, and 97%, respectively. The agreement for determining the degree of stenoses with multislice CT angiography and selective coronary angiography was only moderate (kappa = 0.58). CONCLUSIONS: Because of the limited spatial resolution, it is not possible with multislice CT angiography to determine the degree the coronary artery stenoses precisely. However, the high negative predictive value indicates that multislice CT may be a suitable tool to reliably rule out coronary artery disease.     

双源CT冠状动脉成像的初步研究

目的初步探讨无需口服控制心率药物准备的双源CT冠状动脉成像的扫描技术和图像质量。方法对215例临床怀疑冠心病或冠状动脉早期病变患者进行无需口服控制心率药物准备的双源CT冠状动脉成像。扫描步骤包括平扫和增强扫描。用平扫图像行冠状动脉钙化积分，用增强扫描图像行多平面重组（MPR）、最大密度投影（MIP）及容积再现技术（VRT）重组。总结双源CT冠状动脉成像的扫描技术和后处理方法。将图像质量分为3级，按冠状动脉分段标准评价各个节段的图像质量。结果215例患者钙化积分值中位数为82．2（2．3～1827．9）。增强扫描平均心率为（80．6±15．3）（57～139）次／min，尽可能使冠状动脉良好显示的后处理方法有：（1）多个时相筛选法；（2）2个或多个时相补充法；（3）早搏去除法和心律不齐移位法。共评价3026个冠状动脉节段，其中图像质量为1级者占97．5％（2951／3026），2级者占2．0％（62／3026），为3级者占0．5％（13／3026）；图像质量为2级和3级的节段多由于呼吸伪影所致。215例患者共91例冠状动脉各节段均未见斑块或狭窄，共诊断〈50％冠状动脉狭窄节段112个，≥50％冠状动脉狭窄节段213个。结论双源CT冠状动脉成像在无需口服控制心率药物准备的情况下可获得非常好的冠状动脉各节段图像，心率不再是影响图像质量的关键因素，通过单时相或多时相重组可良好显示冠状动脉主干及分支。     

Noninvasive evaluation of coronary artery bypass graft patency using three-dimensional angiography obtained with contrast-enhanced electron beam CT

OBJECTIVE: The purpose of this study was to determine the accuracy of three-dimensional coronary angiography obtained with electron beam CT in the assessment of the patency of coronary artery bypass grafts. SUBJECTS AND METHODS: Twenty-five patients who had undergone coronary artery bypass graft surgery were included. All patients underwent electron beam CT and conventional coronary angiography for the evaluation of the status of their bypass grafts. Three-dimensional reconstructions of the heart and bypass grafts were compared with selective angiographic images of the bypass grafts. RESULTS: Fifty-seven saphenous vein grafts and 22 left internal mammary artery grafts were evaluated for occlusion or patency. Sensitivity and specificity of electron beam CT in revealing left internal mammary artery patency were 80% and 82.4%, respectively. Sensitivity and specificity of electron beam CT in revealing saphenous vein graft patency were 91.7% and 91.1%, respectively. Sensitivity and specificity of electron beam CT for evaluating saphenous vein grafts according to coronary area were as follows: saphenous vein grafts to left anterior descending artery, 100% and 100%, respectively; to diagonal branch, 100% and 100%; to left circumflex artery, 100% and 88.9%; and to right coronary artery, 75% and 85.7%. CONCLUSION: Three-dimensional coronary angiography obtained with electron beam CT is a promising, useful, and relatively accurate diagnostic imaging technique for the evaluation of graft patency in patients who have undergone coronary artery bypass graft surgery.     

Coronary arterial stent patency: assessment with electron-beam CT

PURPOSE: To evaluate electron-beam computed tomography (CT) for stent localization and noninvasive assessment of stent patency in patients with coronary arterial stents and coronary bypass stents. MATERIALS AND METHODS: CT in the single-section volume mode was performed in 202 patients with 321 coronary arterial stents in 221 vessels to localize the stents. Patency was evaluated in the multisection flow mode with an intravenous bolus injection of contrast material. All electron-beam CT images were reviewed by an observer who had no knowledge of the coronary angiographic results. Electron-beam CT findings were then compared with coronary angiographic findings. RESULTS: The stents could be visualized and related to the coronary arterial segments in 216 of 221 vessels with electron-beam CT. Of the 221 vessels, 207 were correctly evaluated with electron-beam CT. Compared with coronary angiography, electron-beam CT permitted the detection of 18 of 23 high-grade stenoses (sensitivity, 78%) and correctly depicted the absence of high-grade stenoses in 189 of 193 vessels with stents (specificity, 98%). Altogether, 18 stenoses were detected correctly at electron-beam CT; the interpretation was false-positive in four vessels (positive predictive value, 82% [18/22 vessels]) and false-negative in five (negative predictive value, 97% [189/194 vessels]). CONCLUSION: Electron-beam CT may be helpful in localizing intracoronary stents and assessing stent patency noninvasively to delay the intervals between catheterizations in an increasing number of patients.     

CCTA技术对冠状动脉狭窄及其钙化斑块的评估

冠状动脉CT血管成像（CCTA）是一种可无创检测冠状动脉粥样硬化性疾病的成像手段,已成为临床筛查及诊断冠心病的首要检查方法。但对于钙化严重的冠状动脉节段,CCTA的特异性及阳性预测值偏低,可导致病人过度治疗,因此限制了CCTA的临床应用。综述钙化斑块伪影对CCTA的影响,并就CCTA对冠状动脉狭窄准确评估的相关技术进展进行分析,以利于临床诊断中提高CCTA对冠状动脉狭窄率的评估。     

Coronary artery calcium measurement with multi-detector row CT: in vitro assessment of effect of radiation dose

The authors assessed in vitro the effect of radiation dose on coronary artery calcium quantification with multi-detector row computed tomography. A cardiac phantom with calcified cylinders was scanned at various milliampere second settings (20-160 mAs). A clear tendency was found for image noise to decrease as tube current increased (P <.001). No tendency was found for the Agatson score or calcium volume and mass errors to vary with tube current. Calcium measurements were not significantly affected by the choice of tube current. Calcium mass error was strongly correlated with calcium volume error (P <.001). The calcium mass measurement was more accurate and less variable than the calcium volume measurement.