A comparison of quantitative coronary angiography systems using a unique set of in vivo coronary stenosis images

OBJECTIVE: To compare the accuracy and precision of measurements of minimum lumen diameter (MLD) among two existing, and one new, quantitative coronary angiography systems. MATERIALS AND METHODS: The analysis was performed using in vivo cinearteriograms of precisely drilled, radiolucent plastic beads that were inserted percutaneously into the coronary arteries of canines. The existing algorithms compared were the ArTrek and the Coronary Measurement System (CMS). The latter was applied in two modes: a mode based on a minimal cost analysis algorithm and a mode based on a gradient field transform. The new algorithm (CorTrek) was also applied in two modes: a mode called the ArTrek compatible mode and a mode known as the 'regression' mode. The latter mode uses a look-up table, based on a phantom calibration step, to readjust the measured MLD to overcome system nonlinearities (overestimation of small diameters and underestimation of large diameters). RESULTS: In the absence of editing, the optimal accuracy (no significant bias) was achieved with the ArTrek compatible algorithm (-0.03 mm for an MLD between 0.83 and 1.83 mm). All other algorithms showed significant under- or overestimation of the MLD within this range. The precision ranged from 0.18 to 0.40 mm without editing, and was best with the ArTrek algorithm. CONCLUSIONS: The present study provides in vivo validation and comparative performance characteristics of a new, accurate coronary quantitative angiography system.     

First direct in vivo comparison of two commercially available three‐dimensional quantitative coronary angiography systems

Aim : The in vivo comparison of the accuracy of two 3‐dimensional quantitative coronary angiography (QCA) systems. Methods : Precision‐drilled plexiglass phantoms with five different luminal diameters (0.5–1.9 mm) were percutaneously inserted into the coronary arteries of four Yorkshire pigs. Twenty‐one angiographic images of these stenotic phantoms were acquired for in vivo validation testing. Quantitative assessments of the minimum, maximum, and mean luminal diameters together with the minimum luminal area were determined using two 3D QCA systems, the CardiOp‐B® and CAAS 5. Results : The CardiOp‐B system significantly underestimated the minimum luminal diameter MLD whilst both systems significantly overestimated the maximum luminal diameter at the minimal luminal area (MLA) over the phantom's true value. The CAAS 5 system had a greater degree of accuracy/mm (mean difference = 0.01 vs. 0.03) and precision/mm (SD = 0.09 vs. 0.23) than the CardiOp‐B in assessing the minimal LD. An increased precision/mm (SD = 0.01 vs. 0.29) and accuracy/mm (mean difference = 0.03 vs. 0.11) in the mean LD was observed with the CAAS 5. In comparing the MLA/mm² the CAAS 5 was more precise/mm² (SD = 0.14 vs. 0.55) and accurate/mm² (mean difference = 0.12 vs. 0.02) to the true phantom MLA compared to the CardiOp‐B system. Conclusions : In a 21 phantom study, the CAAS 5 3D QCA system had a greater degree of accuracy and precision in both the luminal and area measurements than the CardiOp‐B 3D QCA system. © 2008 Wiley‐Liss, Inc.     

Comparison of vessel diameters in electron beam tomography and quantitative coronary angiography

Electron beam tomography (EBT) has been shown to permit non-invasive imaging of the coronary arteries after intravenous injection of contrast agent and 3-dimensional reconstruction. We compared the vessel diameters in EBT reconstructions to quantitative coronary angiography (QCA). 10 patients were investigated by EBT and QCA. 3-dimensional EBT reconstructions (shaded surface display) were performed after acquisition of 40 axial cross-sections of the heart with 3 mm slice thickness (1 mm overlap) which were obtained triggered to the ECG in breathhold following intravenous injection of 120–160 ml of contrast agent. A fixed lower reconstruction threshold of 80 HU was used to selectively visualize the contrast-enhanced coronary artery lumen. At 60 sites in the coronary artery system, the vessel diameters measured in the EBT reconstructions were compared to the diameters found in quantitative analysis of the patients' coronary angiograms. The correlation coefficient of the vessel diameters in EBT and QCA was 0.83. Mean vessel diameters were not significantly different in EBT and QCA (3.06±0.93 vs. 2.97±0.94 mm). However, very small vessel diameters tended to be underestimated in the EBT reconstructions, which was due to the partial volume effect. If only vessel diameters measured in the left main or left anterior descending coronary artery were compared to QCA, the correlation increased to 0.87, since these vessel segments are less prone to artifacts in the EBT investigation. Vessel diameters in EBT and QCA correlate reasonably well. Due to partial volume effects, the diameter of very small vessels and stenotic segments tends to be underestimated by EBT.     

Accuracy and precision of quantitative arteriography in the evaluation of coronary artery disease after coronary bypass surgery A validation study

Computer-assisted quantitative coronary arteriography (QCA) has gained widespread acceptance in assessing changes in coronary dimensions over time, but little is known about the utility of QCA in patients having undergone coronary bypass surgery. As a validation study, we analyzed the accuracy and precision of QCA in a subset of the baseline angiograms of a clinical trial in 395 post-bypass men with low HDL cholesterol concentrations who have been randomized to receive double-blind gemfibrozil or placebo for 2 1/2 years. Based on repeat measurements of the same cineframe, the average diameter of a segment (ADS) had a mean coefficient of variation (CV) of 3.1 %. The mean CVs of the minimum luminal diameter (MLD), percent diameter stenosis (PDS) and stenotic flow reserve of an obstruction were 8.6, 10.2 and 9.8%, respectively, but the area of the atherosclerotic plaque had an unacceptably high CV, 24.0%. When the measurements from two contrast injections into a native coronary artery during the same angiographic session were compared, precision (standard deviation of the differences) was 0.198 mm for ADS, 0.192 mm for MLD, and 7.37% for PDS. Variability was not substantially reduced when measurements from 3 or 5 consecutive cineframes were averaged. Comparable repeatability was found when venous bypass grafts were imaged twice, whether the grafts themselves or the grafted native vessels were analyzed. We conclude that QCA has an acceptable accuracy and precision in analyzing coronary dimensions in bypass-grafted patients. A change of 0.40 mm in ADS and MLD, and 20% in PDS represent true progression or regression of coronary atherosclerosis with more than 95% confidence.Abbreviations CAD coronary artery disease - CMS Cardiovascular Measurement System - MLD minimum luminal diameter (of an obstruction) - ADS average diameter of a segment - PDS percent diameter stenosis (of an obstruction) - QCA quantitative coronary arteriography - SFR stenotic flow reserve (of an obstruction)     

Sources of error in quantitative coronary angiography

Many studies have reported the accuracy of quantitative coronary angiography (QCA) based on experiments using moderated-size phantoms imaged under unrealistic radiographic conditions. However, these observations may not be generalizable to the setting of clinical angiography. To determine QCA accuracy in a realistic radiographic setting and evaluate the impact of the x-ray system line spread function, plexiglass phantoms were imaged inside and out of a human thorax. A realistic radiographic background was associated with a 38% increase in variability of results (p < 0.05). Low concentrations of contrast and large image intensifier input screens were associated with significantly larger errors and variability in results (p < 0.05). There was a systematic overestimation of diameter in the smallest phantom. A mathematical model of the x-ray line spread function was developed that explains the observed overestimation of the smallest phantom and provide a rational approach for correction of the line spread function for QCA. Many factors encountered in clinical coronary angiography such as nonuniform radiographic background, low concentrations of contrast, and small vessel diameters have a significant adverse impact on the accuracy and/or variability of gradient-based edge detection QCA systems. © 1993 Wiley-Liss, Inc.     

Comparisons of angiographic core laboratory analyses of phantom and clinical images: Interlaboratory variability

Centralized, quantitative coronary analysis (QCA) has become the standard for determining change in coronary anatomy in clinical investigations. QCA systems and laboratory methods, however, vary among core facilities, and analysis variability among angiographic core laboratories (ACL) has not be studied. We evaluated QCA accuracy and variability among active ACL, using differing QCA systems by comparing analyses of phantom and clinical cinefilm images. Automated, unedited analyses were performed on images of 11 plexiglass phantom lumens (0.67–5.05 mm) acquired under varying radiographic conditions. Analysis differences from actual luminal diameters ranged widely (+0.42–−0.45 mm) among ACL. Measurement of diameters <1.0 mm were overestimated and diameters >3.0 mm were underestimated. Measurements of midrange diameters (>1.0 mm and <3.0 mm) were most comparable among ACL (93% within ±0.2 mm). Clinical image analysis was performed using differing QCA systems and laboratory methodology on 11 randomly selected study films. Comparative analyses revealed significant variability between laboratories in the assessment of minimal lumen diameter (0.22 ± 0.38 mm P < 0.05). These data describe analysis variability among ACL and demonstrate a need for establishing ACL performance standards. © 1996 Wiley-Liss, Inc.     

Pitfalls in the determination of absolute dimensions using angiographic catheters as calibration devices in quantitative angiography

Using catheter outer diameter as a scaling device, quantitative coronary arteriography allows the precise and objective measurement of change in absolute dimensions of coronary arteries after mechanical or pharmacologic intervention. Because of variable density in the wall of the catheter, automated systems might vary in the determination of the outer catheter diameter. To examine this premise, catheters in a variety of French sizes from 6 manufacturers were injected with radiographic contrast and used as scaling devices for arterial phantoms of known geometric dimension. Radiographic diameters of the catheters were determined by applying the quantitative coronary arteriographic algorithm to the catheters using a calibration grid in the same field of view. The varying composition of the catheters resulted in differing x-ray attenuation and, subsequently, automated edge-detection algorithms varied widely in determining the actual catheter diameter to be used as a scaling factor. For instance, a Lucite "artery" with a minimal luminal diameter of 1.50 mm (image calibrated using the micrometer-determined outside diameter of a Baxter 8Fr guiding catheter) resulted in a quantitative angiographic diameter of 2.03 mm (overestimation by 35%). If the diameter of a similar size Shiley catheter was used to calibrate the image, a luminal diameter of 1.60 mm was determined: a difference of 0.43 mm based solely on differences in scaling catheter attenuation. These data suggest that a specific "fingerprint" for each catheter material and catheter French size exists, rendering generalizations about catheter size questionable. These observations are important for quantitative angiography where many brands and sizes of angiographic catheters are being used clinically.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of the degree of coronary stenoses by multidetector computed tomography versus by quantitative coronary angiography

Sixteen-slice multidetector computed tomography (MDCT) and quantitative coronary angiography (QCA) were performed in 29 patients. Quantification of the degree of luminal narrowing and lesion length measurements were performed independently on MDCT and QCA at 42 sites with sufficient computed tomographic image quality. The correlation between MDCT and QCA for quantifying the degree of stenosis was excellent (r2 = 0.93), although a systematic overestimation was observed by MDCT (bias 4% +/- 8%). The correlation between MDCT and QCA was moderate with respect to lesion length (r2 = 0.54). In the absence of severe calcifications or motion artifacts, MDCT permits noninvasive quantification of coronary stenosis.     

Evaluation of catheters and metallic catheter markers as calibration standard for measurement of coronary dimension

Measurement of coronary dimension requires an accurate and reproducible dimensional reference. Angiographic catheters are frequently used for this purpose. We measured the angiographic diameters of a broad range of diagnostic and angioplasty guiding catheters by using two commonly used edge-detection algorithms. Angiographic diameters are significantly less than true catheter outer diameter. Therefore the use of contrast-filled catheters as a dimensional reference may lead to considerable error in vessel measurement with overestimation of absolute dimension. Tables of reference values for multiple catheter as calibration standard, tested under a variety of angiographic conditions. The metallic-tipped marker was found to have a better degree of reproducibility than catheters. These findings have implications for studies employing serial measurements of coronary artery dimension and for the clinical practice of estimating vessel diameter for choice of balloon size during angioplasty.     

Validation of an accurate method for three-dimensional reconstruction and quantitative assessment of volumes, lengths and diameters of coronary vascular branches and segments from biplane angiographic projections

The goal of the study was the validation of an accurate method for three-dimensional reconstruction and quantitative assessment of volumes, lengths and diameters of coronary vascular branches and segments from biplane angiographic projections. Methods: The accuracy was tested in a complex phantom. In vivo, inter- and intraobserver agreement were assessed by analysis of routine angiograms. The sensitivity was evaluated using angiograms of patients having diagnostic vasoactive pharmacological intervention. Two-dimensional quantitative coronary angiography (2-D QCA) and 3-D QCA were compared concerning the accuracy of diameter evaluation. Results: 3-D QCA yields accurate results ( <3% error) even based on nonorthogonal views, provided that projections parallel to the object are avoided. The inter- and intraobserver variability is 5%. Significant (p < 0.01) changes of the volume (36–39%) and the diameter (19–21%) are detected following pharmacological intervention. 2-D QCA and 3-D QCA agree in short matched segments without foreshortening. 2-D QCA is rather sensitive to foreshortening and not suitable for evaluation of diameters of longer branches or total coronaries. Conclusion: 3-D QCA permits an accurate, reproducible and sensitive comprehensive three-dimensional geometric analysis of the coronaries and is superior to 2-D QCA with respect to extended diameter evaluation.     

Comparison of different quantitative coronary analysis systems: ARTREK,CAAS, and CMS

It has been known that the first generation quantitative coronary analysis systems overestimate small vessel sizes. In the 2nd generation the contour detection algorithms, e.g., of the new Cardiovascular Measurement System (CMS), were modified to correct for the limited resolution of the X-ray imaging chain. This study validated and compared the CMS with the well-known Coronary Angiography Analysis System (CAAS) and the vessel tracking program ARTREK in a phantom study and a clinical study. In addition, the influence of different acquisition media (cinefilm vs. digitally acquired angiograms) on the accuracy of quantitative analysis was examined. The phantom study comprised 19 stenotic or non-stenotic glass tubes with a diameter range from 0.54 mm to 4.9 mm. In the clinical study the mean diameters of 322 coronary segments were analysed and the results of the systems were compared among each other. The results of the phantom study were presented in terms of the mean difference (accuracy) between true and measured values. In the phantom study the overall accuracy of the CMS was −6 μm (ARTREK: 85 μm; CAAS: 35 μm) with an overestimation of small vessels of only −11 μm (ARTREK: 97 μm: CAAS: 51 μm). The clinical study showed that the CMS corrected the usually occurring overestimation of small coronary arteries and that the influence on the accuracy of different acquisition media is minor. Due to the modified algorithms the new CMS is able to measure coronary diameters down to 0.5 mm accurately. Therefore, the CMS seems to provide more precise measurements in quantitative analysis of small coronary diameters than CAAS and ARTREK. © 1996 Wiley-Liss, Inc.     

Quantitative measurements of in-stent restenosis: A comparison between quantitative coronary ultrasound and quantitative coronary angiography.

While quantitative coronary angiography (QCA) remains the standard used to assess new interventional therapies, intracoronary ultrasound (ICUS) is gaining interest. The aim of the study was to determine the relationship between QCA and quantitative coronary ultrasound (QCU) measurements after stenting. Sixty-two consecutive patients with both QCA and QCU analysis after stent implantation were included in the study. The mean luminal diameter (QCU vs. QCA) were 2.74 +/- 0.46 mm and 2.41 +/- 0.49 mm (P < 0.0001), the minimal luminal diameter (MLD) 2.08 +/- 0.44 mm and 1.62 +/- 0.42 mm (P < 0. 0001), and the projected QCU MLD 1.90 +/- 0.42 mm (P < 0.0001 with respect to QCA). Percentage obstruction diameter (QCU vs. QCA) were 41.53% +/- 10.78% and 43.15% +/- 12.72% (P = NS). The stent diameter (QCU vs. QCA) were 3.54 +/- 0.65 mm and 3.80 +/- 0.37 mm (P = 0. 0004). Stent length measured by QCU were longer at 31.11 +/- 13.54 mm against 28.63 +/- 12.75 mm, P < 0.0001 with respect to QCA. In conclusion, while QCA and QCU appear to be comparable tools for measuring corrected stent diameters and stent lengths, smaller luminal diameters were found using QCA. This is of particular relevance to quantitative studies addressing absolute changes in vascular or luminal diameters. Cathet. Cardiovasc. Intervent. 48:133-142, 1999.     

Radiological quality of coronary guiding catheters: A quantitative analysis

Quantitative coronary angiography (QCA) is a validated and widely accepted method to investigate changes in arterial dimension over time. Calibration of measurements is enabled by the use of the coronary catheter as a scaling device. The dimensions and laminar composition of coronary catheters, however, have changed significantly over recent years and the suitability of the current generation of coronary catheters for calibration purposes has not been validated. We therefore recorded 57 coronary guiding catheters on cinefilm, and compared their automated quantitative measurements (Cardiovascular Angiography Analysis System, CAAS) with their true values (precision micrometer). We found an overall underestimation of quantitatively derived dimensions, ranging from ?8.9 to +4% for water-filled catheters and from ?15.5 to ?3.9% for contrast-filled catheters. In conclusion, while the current generation of coronary guiding catheters shows a wide variety in radiological quality, it can be clearly detected by the CAAS system, and is suitable for calibration of QCA measurements (with the exception of the DVI atherectomy catheter), provided that calibration is done on contrast-empty catheters. © Wiley-Liss, Inc.     

Overestimation of stent delivery balloon diameters by manufacturers' compliance tables: a quantitative coronary analysis of Duet and NIR stent implantation.

Although manufacturers' compliance tables of stent delivery balloons indicate the diameter of the balloon at a given inflation pressure, it is unclear whether these data correlate with in vivo true intracoronary balloon diameters (TBDs). The TBDs of two new-generation balloon-expandable stent delivery systems (Duet and NIR) were measured by quantitative coronary analysis (QCA) in 100 consecutive patients. The manufacturers' stated balloon diameter (BD) of the stent delivery systems overestimated the TBD in 94% +/- 4% of patients receiving both Duet or NIR stent implantations. In only 6% of the patients, the TBD matched the manufacturers' stated balloon diameter. There was no underestimation of TBDs by both manufacturers' compliance tables. The Duet tables overestimated TBDs by 14% +/- 8% (range, 1%-36%), the NIR tables by 18% +/- 8% (range, 1%-41%), P < 0.05, Duet vs. NIR, respectively. When the manufacturers' data were corrected for the differences in reporting data from in vitro tests, i.e., balloon compliance data with or without the stent, the degree of overestimation of diameters was similar for Duet and NIR stent delivery balloons (14% +/- 8% vs. 13% +/- 7%, Duet vs. NIR; P = NS). Manufacturers' compliance tables of both the Duet and NIR stent delivery balloon systems significantly overestimate the true intracoronary balloon diameter. The manufacturers' of stent delivery balloons should clearly state on the box, if balloon compliance data were derived from in vitro bench testing, which phantoms were used for compliance analysis, and that the tables may overestimate the true intracoronary balloon diameter. The findings of the present study have important clinical implications with respect to performing coronary stent implantation with precision.     

Contrast enhanced multi-detector computed tomography coronary angiography versus conventional invasive quantitative coronary angiography in acute coronary syndrome patients-correlation and bias

BACKGROUND: Previous studies that compared multi-detector computed tomography (MDCT) non-invasive coronary angiography with conventional coronary angiography, did not assessed the ability of MDCT to detect stenotic lesions correctly in acute coronary syndromes (ACS) patients. The aim of the present study was to assess prospectively the correlation and bias between 16-slice MDCT coronary angiography and quantitative coronary angiography analysis (QCA) in these patients. METHODS: Patients underwent electrocardiogram-gated, 16-slice MDCT coronary angiography and routine invasive percutaneous coronary angiography with quantitative coronary angiography (QCA) analysis blinded to MDCT results. The correlation and the bias between the results of MDCT and QCA were assessed in segments observed by both modalities in vessels > or = 2 mm in diameter. RESULTS: 59 patients (81% male, age 56 +/- 11 years), admitted due to ACS, underwent MDCT and invasive coronary angiography. 544 segments were analyzed. The correlations between MDCT and QCA observed for the left anterior descending coronary artery (LAD), the left circumflex coronary artery (Cx), the right coronary artery (RCA) and for all analyzed segments were 0.74 (P < 0.0001), 0.54 (P < 0.009), 0.72 (P < 0.0001) and 0.70 (P < 0.0001), respectively. By Bland-Altman analysis, a small overestimation of the lesion severity with MDCT of 4.8% for the LAD, 5.9% for the Cx, and 3.3% for the RCA was observed. CONCLUSIONS: In ACS patients, MDCT contrast-enhanced coronary angiography provides good quantification of the luminal diameter as compared to coronary angiography, and it is characterized by a small overestimation bias.     

Comparison of automated quantitative coronary angiography with caliper measurements of percent diameter stenosis

Measurement of coronary artery stenosis is an invaluable tool in the study of coronary artery disease. Clinical trials and even day-to-day decision making should ideally be based on accurate and reproducible quantitative methods. Quantitative coronary angiography (QCA) using digital angiographic techniques has been shown to fulfill these requirements. Yet many laboratories have abandoned visual analysis in favor of the intermediate quantitative approach involving hand-held calipers. Thus, the purpose of this study was to determine the relation between QCA and the commonly used caliper measurements. Percent stenosis was assessed in 155 lesions using 3 techniques: QCA, caliper measures from a 35-mm cine viewer (cine) and caliper measures from a video display (CRT). Good overall correlation was noted among the 3 different techniques (r greater than or equal to 0.72). Both of the caliper methods underestimated QCA for stenosis greater than or equal to 75% (p less than or equal to 0.001) and overestimated stenosis less than 75% (p less than 0.05). Reproducibility assessed in 52 lesions by independent observers showed QCA to be superior (r = 0.95) to either of the caliper measurements (cine: r = 0.63; CRT: r = 0.73). Therefore, the commonly used caliper method is not an adequate substitute for QCA because overestimation of noncritical stenoses and underestimation of severe stenoses may occur and the measurements have poor reproducibility. These factors definitely preclude its use in rigorous clinical trials. Moreover, since they do not appear to overcome known deficiencies of visual analysis, caliper measurements for day-to-day clinical use must also be seriously questioned.     

Quantitative coronary arteriography on digital flat-panel system.

On images acquired with a digital flat-panel (DFP) detector, known for its better image quality, the performance of a validated quantitative coronary arteriography (QCA) software, CAASII (Cardiovascular Angiography Analysis System or CAAS), and a DFP-dedicated QCA algorithm (flat-panel analysis software or FPAS) was compared in a phantom and a patient study. On phantom, FPAS performed with higher accuracy the quantification of the smallest tubes and the calibration of an empty catheter. The overall accuracy and precision for the quantification procedure was better for FPAS (0.07 +/- 0.04 mm) than for the CAAS (0.19 +/- 0.06 mm; P = 0.03 and P < 0.01, respectively). In the patient study, the main difference between the two algorithms was found in the small diameters: CAAS almost always gave higher values than FPAS for the minimal luminal diameter (P < 0.001) and could only give values up to 70% for diameter stenosis. In conclusion, the FPAS can be considered more appropriate for assessing severe stenoses on digital flat-panel images.     

Reproducibility of quantitative coronary analysis

Because of limited storage capacity for digital images, angiographic laboratories without cinefilm are dependent on locally performed quantitative coronary angiography (QCA) in clinical studies. In the present study the intra-and interobserver variability, as well as variability between different laboratories and variability due to frame selection was analyzed. A total of 20 coronary lesions were studied in two different digital laboratories 12±8 days apart. Images were analyzed on-line and after being transferred to a Cardiac Work Station (CWS). There was no significant difference between the measurement situations. For minimal luminal diameter (MLD) precision (SD of signed errors) ranged from 0.12 mm to 0.20 mm, for reference diameter (RD) from 0.15 mm to 0.28 mm, and for percent diameter stenosis (DS) from 4.2% to 5.8%. Overall relative precision was obtained by normalizing the QCA parameters, and was 11.9% for MLD, 7.0% for RD and 8.5% for DS (p<0.001, RD and DS compared to MLD). The overall variability in the interobserver and in the interlaboratory comparisons was 11.2% and 10.4%, respectively (n.s.) (n.s.). Thus the variability of QCA performed in cinefilmless, digital laboratories is small, and within a range making it an useful tool for clinical practice and group comparisons in clinical studies. However, the error range of QCA measurements must be taken into consideration when judging results from individual patients.     

血管内超声在冠状动脉临界病变中的应用研究

目的:研究传统冠状动脉定量分析方法(QCA)与血管内超声(IVUS)在冠状动脉临界病变中的应用。方法:共入选经过冠状动脉造影(至少4体位造影)证实病变狭窄处于临界病变的患者150例。将入选者分为:常规冠状动脉造影组90例(QCA),血管内超声组60例(IVUS)。通过QCA和血管内超声定量分析方法分析2组最小管腔直径、参考血管直径、直径狭窄率及最小管腔面积等参数指标;将相关数据建立直线回归分析方程,分析二者之间是否具有线性关系;采用Cox回归模型分析2组免于心血管事件方面差异,观察2组术后住院期间、30d、3个月、6个月、9个月和12个月主要心血管事件。结果:血管内超声组分别采用QCA和IVUS分析,参考血管直径2者具有正相关性分别为(3.28±0.19)mmvs.(3.17±0.21)mm,R=0.627。最小管腔直径分别为(2.04±0.18)mmvs.(2.0±0.17)mm,R=0.782。比较2组之间的参数:QCA组通过计算得出直径狭窄率,与IVUS管腔面积狭窄率之间无相关性(R20.05,P=0.222),IVUS最小管腔面积(4.7±0.67)mm2。通过COX回归模型显示2组在免于心血管事件方面的差异,可见QCA组发生心血管事件率具有较高的趋势。结论:对于临界病变的患者,采用IVUS的方法能够检测出更严重狭窄的发生率,传统冠状动脉造影判定结果往往低估真正的病变情况。对于临界病变的患者,采用IVUS进行测量分析,具有减低心血管事件风险的趋势。     

Intravascular ultrasound and quantitative coronary angiography assessment of late in-stent restenosis: in vivo human correlation and methodological implications.

Quantitative coronary angiography (QCA) is routinely used for assessment of strategies aimed at reducing in-stent restenosis. Yet QCA enables only the measurement of luminal variation of stented segments and, unlike intravascular ultrasound (IVUS), provides only an indirect estimation of late in-stent neointimal formation, which has a key role in the process of in-stent restenosis. The aims of the present study were to correlate the IVUS measurement of in-stent intimal hyperplasia (IH) with QCA indexes of restenosis, to find out whether QCA is an adequate surrogate of IVUS, and, using either QCA and IVUS data, to define the sample sizes needed to demonstrate the effectiveness of strategies to reduce in-stent restenosis. The database of the European Imaging Laboratory was used to screen 154 stents implanted between 1997 and 2001 and studied by IVUS at 6 +/- 1 months of follow-up. All cases underwent serial QCA assessment (preintervention, postintervention, and follow-up). Only 131 cases with single stent implantation in native coronary arteries were included in the study. Stent restenosis, defined as percent diameter stenosis (DS) > 50%, was present at QCA in 69 out of 131 cases (53%). Linear regression analyses were performed to correlate the amount of IH, calculated by IVUS as the average of all cross-section areas (CSA; mean % IH CSA) and QCA indexes of restenosis (late loss and % DS). A positive significant correlation was found between IVUS mean % IH CSA and QCA % DS (r = 0.74; P < 0.0001) and between IVUS mean % IH CSA and QCA late loss (r = 0.72; P < 0.0001). Based on IVUS measurements of mean % IH CSA, a total sample size of 74 stents would be required in a two-arm comparison to have 0.80 power to detect at 0.05 significant level a 30% difference between two compared groups. Alternatively, adopting the QCA late loss, 230 stents would be required. QCA measurements of late in-stent restenosis are well correlated with IVUS calculation of in-stent neointimal formation. IVUS assessment of IH allows smaller sample sizes than QCA to document significant reductions of in-stent restenosis. Therefore, the use of IVUS should be encouraged in comparison studies aimed at revealing significant neointimal differences in small sample size populations.