Quantitative Coronary Arteriography Research Articles

Coronary tandem lesions: Effect of exercise

Coronary vasomotion of two stenoses in series (i.e., tandem lesion) was studied in 10 patients with coronary artery disease. Percent area stenosis was 69% ± 23% for the first (S1) lesion and 70% ± 37% for the second (S2). Quantitative coronary arteriography was carried out at rest, during two levels of exercise (2 minutes, 75 W and 1.9 minutes, 100 W), and at 5 minutes after sublingual administration of 1.6 mg nitroglycerin. Both stenoses showed exercise-induced vasoconstriction (S1: −29%, p < 0.01 versus rest; S2: −29%, p < 0.01 versus rest), which was reversible after sublingual administration of nitroglycerin (S1: +15%, not significant versus rest; S2: +13%, not significant versus rest). The vessel segment between the two stenoses showed no vasomotion during exercise, whereas the pre- and poststenotic “normal” vessel segment elicited exercise-induced vasodilation. There was an inverse relationship between percent area stenosis of the second lesion and exercise-induced vasoconstriction of the first lesion (correlation coefficient = 0.84). The more severe the distal stenosis was, the less exercise-induced stenosis narrowing of the proximal lesion was observed. Thus it is concluded that coronary vasomotion of two stenoses in series is dependent on both active and passive mechanisms because both lesions show exercise-induced vasoconstriction, but vasomotion of the proximal lesion is dependent on the severity of the second one.

Influence of operator- and patient-dependent variables on the suitability of automated quantitative coronary arteriography for routine clinical use

This study was designed to elucidate the operator- and patient-dependent variables inherent in clinical application of quantitative coronary arteriography. Digital arteriograms from 25 consecutive patients undergoing diagnostic catheterization were analyzed by four experienced angiographers utilizing an automated coronary edge detection system to measure percent area stenosis.The identification of potentially significant lesions for quantitation constituted a major source of variability, with unanimous agreement on the presence of a ≥50% stenosis occurring at 38 (29%) of the 130 reported sites. Selection of an optimal frame for quantitative analysis resulted in disagreement for every lesion reported. Frame selection by the operator, as opposed to measurement of preselected frames, increased the interobserver variability from 5% to 7% for automated geometric analysis (p < 0.01), and from 8% to 10.5% for automated densitometric analysis (p < 0.01).Fully automatic arterial border detection was possible for only 20 (52.5%) of the 38 unanimously identified stenoses. The 18 failures involved one or more of the following factors: 1) stenosis at a bifurcation (13 [72%]); 2) diffuse, severe disease (8 [44%]); 3) excessive vessel tortuosity or overlap or both (4 [22%]); and 4) poor image quality (5 [28%]). In contrast, the same automated border detection algorithm successfully traced all 15 preselected frames of discrete stenoses referred for coronary angioplasty.Automated quantitative coronary arteriography performs well when carefully selected, discrete stenoses are presented to the computer for analysis. However, quantitative analysis of routine clinical coronary arteriograms is limited by operator-dependent variability in stenosis identification and frame selection, as well as by complex coronary anatomy and suboptimal image quality. These limitations make automated quantitative coronary arteriography impractical for routine clinical use.

Prognostic importance of quantitative analysis of coronary cineangiograms

Many studies have shown the prognostic value of angiographic data, but few have examined quantitative parameters of wall motion and shape or coronary stenosis severity. To determine whether these parameters have prognostic importance, baseline angiograms of 283 patients with up to 11.2 years (mean 8.3) of follow-up were quantitated. Event-free survival curves were constructed using log-rank testing. These indexes were also considered in 2 predictive models (Cox regression models): 1 with (“clinical”) and 1 without (“quantitative”) subjective angiographic analysis and clinical information. Regional shape (anterior and inferior walls) and motion (anterior wall only) indexes were predictive of event-free survival when considered singly. But these parameters were not of independent prognostic importance in the regression models. The most important independent parameters in the quantitative model for predicting overall cardiac mortality or an initial lethal cardiac event were the ejection fraction and the percent diameter narrowing of each major coronary artery. Myocardial infarction was predicted by the percent diameter stenosis of the left main and left anterior descending arteries but not the ejection fraction. In the clinical model, the factors of overriding prognostic importance were the ejection fraction and the subjective determination of the number of vessels involved with “significant” stenoses. Quantitative coronary arteriography still contributed independent prognostic value. Thus, quantification of the ejection fraction and severity of coronary lesions were of independent, prognostic importance, whereas indexes of regional function and shape were not.

Improved stenosis geometry by quantitative coronary arteriography after vigorous risk factor modification

This study is a randomized, controlled, blinded, arteriographic trial to determine the effects of a low-cholesterol, low-fat, vegetarian diet, stress management and moderate aerobic exercise on geometric dimensions, shape and fluid dynamic characteristics of coronary artery stenoses in humans. Complex changes of different primary stenosis dimensions in opposite directions or to different degrees cause stenosis shape change with profound effects on fluid dynamic severity, not accounted for by simple percent narrowing. Accordingly, all stenosis dimensions were analyzed, including proximal, minimal, distal diameter, integrated length, exit angles and exit effects, determining stenosis shape and a single integrated measure of stenosis severity, stenosis flow reserve reflecting functional severity. In the control group, complex shape change and a stenosis —molding characteristic of statistically significant progressing severity occurred with worsening of stenosis flow reserve. In the treated group, complex shape change and stenosis molding characteristic of significant regressing severity was observed with improved stenosis flow reserve, thereby documenting the multidimensional characteristics of regressing coronary artery disease in humans.

Regression of coronary artery dimensions after successful aortic valve replacement.

The effect of regression of myocardial hypertrophy on coronary artery dimensions was evaluated in patients with aortic valve disease who underwent valve replacement. Cross-sectional area (CSA) of the three major coronary arteries (left anterior descending [LAD], left circumflex [LCx], and right coronary artery) was determined by quantitative coronary arteriography in 15 patients with aortic valve disease before and 38 months (range, 14-113 months) after successful aortic valve replacement. Twelve normal subjects served as controls. Left ventricular (LV) angiographic mass was calculated according to the method of Rackley. CSA of the left coronary artery was larger in aortic valve disease than in controls (LAD, 15 versus 8 mm2, p less than 0.001; LCx, 14 versus 6 mm2, p less than 0.001). After valve replacement, CSA of the left coronary artery decreased (LAD, 12 mm2, p less than 0.05 versus before surgery; LCx, 11 mm2, p less than 0.05 versus before surgery) but remained significantly larger than in controls. CSA of the right coronary artery in patients with aortic valve disease was not different from controls. LV muscle mass was significantly increased in aortic valve disease patients before (364 g) and after (250 g) valve replacement compared with controls (135 g). The appropriateness of coronary artery size with respect to muscle mass was evaluated by normalizing CSA of the left coronary artery (LAD + LCx) per 100 g of LV muscle mass (mm2/100 g). This index amounted to 11 mm2/100 g in controls, to 8 mm2/100 g in preoperative patients (p less than 0.05 versus controls), and to 10 mm2/100 g in postoperative patients with aortic valve disease (p = NS versus controls). In patients with aortic valve disease, CSA of the proximal LAD and LCx is increased, but this increase is not sufficient to keep CSA per 100 g of LV mass within normal limits. The postoperative decrease in muscle mass is associated with a decrease in the size of LAD and LCx, whereas the size of the right coronary artery remains unchanged. In contrast to the preoperative state, the residually hypertrophied LV myocardium after aortic valve replacement is supplied by an enlarged but adequately sized LAD and LCx.

Effect of coronary stenosis severity on variability of quantitative arteriography, and implications for interventional trials

Quantitative coronary arteriography is now routinely used in studies assessing arterial remodelling in response to interventions such as lipid lowering and percutaneous transluminal coronary angioplasty. Although this methodology provides both relative and absolute measurements that can be evaluated statistically as continuous variables, it is, however, often desirable or necessary to establish categorical responses to the interventions based on the variability inherent in the quantitative methods (i.e., it is often necessary to state whether individual patients, as opposed to entire groups, have “restenosed,” “progressed,” “regressed,” and so forth, and these categorical designations are based on critical limits of variability). 1,2 These limits are generally based on an analysis of a rather diverse range of lesion severity, and the question arises as to whether the variability of measuring changes in lesion or segment morphology is affected by the initial severity of the lesion being studied. It is conceivable that variability may be greater at 1 end than at the other end of the spectrum of lesion severity. If this is true, then the use of 1 critical value to designate whether a subject has responded in a certain way would be inappropriate, and this designation would be better achieved by using criteria that more directly reflect the measurement variability of lesions of a specified, initial severity. This report examines whether the variability of measuring morphologic parameters of stenoses is affected by the baseline severity of the lesion.

Clinical angiographic and histologic correlates of eetasia after directional coronary atherectomy

Directional coronary atherectomy can cause ectasia (final area stenosis < 0%), presumably due to an excision deeper than the angiographically “normal” arterial lumen. In a multicenter series in which quantitative coronary arteriography was performed after directional atherectomy in 382 lesions (372 patients), ectasia after atherectomy occurred in 50 (13%) lesions. By univariate analysis, ectasia was seen more often within the circumflex coronary artery (p = 0.008), in complex, probably thrombus-containing lesions (p = 0.015), and with higher device: artery ratios (p < 0.001). Ectasia occurred less often in lesions within the right coronary artery (p = 0.008). Histologic analysis demonstrated adventitia or media, or both, in all patients with angiographic ectasia. Repeat angiography was performed in 188 of 271 eligible patients (69%) 6.1 ± 2.4 months after atherectomy. Restenosis, defined as a follow-up area stenosis ≥ 75%, was present in 50% of patients without procedural ectasia and in 70% of patients with marked ectasia (residual area stenosis <-20%; p = 0.12). It is concluded that excision beyond the normal arterial lumen may occur after directional coronary atherectomy, related, in part, to angiographic and procedural features noted at the time of atherectomy. Restenosis tends to occur more often in patients with marked ectasia after coronary atherectomy.

Impaired endothelium-dependent cholinergic coronary vasodilation in patients with angina and normal coronary arteriograms

The coronary vasomotor responses to selective infusion of graded concentrations (10−6to 10−4M) of acetylcholine into the left anterior descending artery were assessed by quantitative coronary arteriography in 24 patients with normal coronary arteriograms (12 patients with atypical symptoms and 12 patients with typical anginal pain) and 36 patients with coronary artery disease with different degrees of atherosclerosis of the left anterior descending artery.In the patients with normal coronary arteries and atypical chest pain, acetylcholine induced predominantly a vasodilator response, which was maximal during a 10−5Macetylcholine infusion. In contrast, in patients with coronary artery disease, acetylcholine caused dose-dependent vasoconstriction, which was observed even if the left anterior descending artery itself was smooth. Marked vasoconstriction was also induced in the patients with typical anginal pain and angiographically normal coronary arteries. In nine of these patients, this constrictor response was associated with anginal pain and elertrocardiographic evidence of myocardial ischemia. Intracoronary administration of isosorbide dinitrate (1 mg) relieved the anginal pain and dilated all vessels.These data suggest that 1) patients with normal coronary arteriograms and angina pectoris manifest impairment of endothelium-dependent vasodilation similar to that observed in patients with overt coronary atherosclerosis; and 2) abnormal coronary vasoconstrictor responses resulting from this impairment may contribute to the pathogenesis of myocardial ischemia and angina in these patients.

Residual coronary stenoses and calculated transstenotic gradients after intravenous streptokinase versus tissue plasminogen activator

To compare the relative success of intravenous streptokinase (STK) and tissue plasminogen activator (TPA) on the severity of residual infarct-related coronary stenoses, we evaluated 45 patients receiving thrombolytic therapy for acute myocardial infarction. Twenty-three patients (18 men and 5 women) received STK (1.5 million units), while 22 patients (18 men and 4 women) received TPA (100 mg) within 6 hours of chest discomfort. Cardiac catheterization was performed before hospital discharge (8 days) with quantitative coronary arteriography and estimation of transstenotic pressure gradients using fluid dynamic equations. Although angina pectoris was equally common (STK, 7 of 23 [30%] versus TPA, 5 of 22 [23%], p = NS), recurrent infarction (STK, 3 of 23 [13%] versus TPA, 7 of 22 [32%], p < 0.05) and coronary angioplasty (STK, 2 of 23 [9%] versus TPA, 7 of 22 [32%], p < 0.05) were more frequent in those receiving TPA. Infarct-related coronary patency was greater in TPA-treated subjects (STK, 15 of 23 [65%] versus TPA, 19 of 22 [86%], p < 0.05), although minimum stenotic diameter (STK, 0.77 ± 0.48 mm versus TPA, 0.57 ± 0.38 mm, p < 0.05), and calculated transstenotic pressure gradient (STK, 8.7 ± 17.0 mm Hg versus TPA, 23.7 ± 30.2 mm Hg, p < 0.05) suggested severe residual stenosis. These effects were accentuated at elevated coronary flow velocities (8 to 20 cm/sec). Myocardial salvage was similar, as indicated by left ventricular ejection fraction (STK, 62.1 ± 12.7% versus TPA, 65.8 ± 28.4%, p = NS) and infarct-territory fractional radial shortening (STK, 27.7 ± 22.7% versus TPA, 29.0 ± 18.3%, p = NS). TPA effectively restores infarct-related coronary artery patency, although increased severity of residual coronary stenosis may result in a greater frequency of recurrent ischemic events.

Normalization of coronary vasomotion after percutaneous transluminal coronary angioplasty?

Coronary vasomotion was evaluated at rest and during bicycle exercise in 33 patients (age, 53 +/- 7 years) with coronary artery disease. In a first group of patients (n = 15), vasomotion was studied before and 4.3 +/- 2.3 months (early) after percutaneous transluminal coronary angioplasty (PTCA), whereas in a second group (n = 18), exercise coronary arteriography was performed 30 +/- 11 months (late) after successful PTCA. Patients with restenosis (percent area stenosis greater than or equal to 75% or percent diameter stenosis greater than or equal to 50%) were excluded. Luminal areas of a normal segment and the stenotic segment were determined at rest, during supine bicycle exercise, and 5 minutes after sublingual nitrate administration by using biplane quantitative coronary arteriography. Work loads before and early after PTCA were identical in group 1 and similar late after PTCA in group 2. Percent area stenosis decreased from 86% to 36% (p less than 0.001) in group 1 and from 93% to 46% (p less than 0.001) in group 2. Normal coronary arteries showed mild vasodilation during exercise before (+3%, NS versus rest), early (+7%, NS versus rest), and late after (+10%, p less than 0.05 versus rest) PTCA. Administration of sublingual nitrate was associated with significant vasodilation of the normal vessel segment before (+27%, p less than 0.001 versus rest), early (+31%, p less than 0.001 versus rest), and late (+21%, p less than 0.001 versus rest) after PTCA. In contrast, the stenotic vessel segments showed coronary vasoconstriction during exercise before PTCA (-25%, p less than 0.001 versus rest), whereas minimal vasomotion was observed early (+2%; NS versus rest) as well as late (+5%; NS versus rest) after PTCA. Individual post-PTCA (early and late) exercise data elicited vasodilation in 19, no vasomotion in four, and vasoconstriction in 10 instances. Sublingual administration of nitrate was associated with a significant increase in minimal luminal area before (+18%, p less than 0.05 versus rest), early (+24%, p less than 0.01 versus rest), and late (+16%, p less than 0.001 versus rest) after PTCA. An inverse linear correlation was found between the percent change in minimal luminal area during peak exercise and percent area stenosis at rest (r = 0.77, p less than 0.001). Exercise-induced stenosis narrowing is observed before PTCA but normal vasomotion is reestablished in two thirds of all patients early and late after PTCA. In one third, an abnormal reaction to exercise (i.e., vasoconstriction) persisted after PTCA, mainly in those patients with a residual area stenosis of 50% (percent diameter stenosis of 30%) or more. Thus, PTCA appears to have a salutary effect on coronary vasomotion during exercise, which, however, remains dependent on the severity of the residual stenosis.

Inappropriate constriction of small coronary vessels as a possible cause of a positive exercise test early after successful coronary angioplasty.

The mechanism responsible for exercise-induced myocardial ischemia early after successful coronary angioplasty (PTCA) is poorly understood. Twelve patients who underwent one-vessel PTCA were studied. Exercise testing was performed before and on day 7 after PTCA, which was repeated after 10 mg sublingual isosorbide dinitrate if the test was positive. Quantitative coronary arteriography was also performed on day 8 after PTCA in the basal state, after intracoronary infusion of 0.9% saline, 1, 5, 10, and 20 micrograms ergonovine, and after 300 micrograms nitroglycerin. All patients had a positive exercise test before PTCA but on day 7, six patients had a positive exercise test (group 1) and six patients (group 2) had a negative exercise test. In group 1, all positive exercise tests on day 7 became negative when repeated after isosorbide dinitrate. Intracoronary ergonovine was associated with a dose-dependent constriction of the PTCA segment, a segment distal to it, and a control segment, with no significant difference in the magnitude of the response between the two groups; maximum constriction for group 1 was 19 +/- 3%, 23 +/- 2%, and 16 +/- 3% (p less than 0.001 versus basal), and in group 2 was 20 +/- 4%, 18 +/- 4%, and 9 +/- 2% (p less than 0.01 versus basal). No angina, ischemic ST segment changes, occlusive, or subocclusive spasm occurred in any patient of either group. We could find no evidence that exercise-induced myocardial ischemia early after PTCA is related to the presence of fixed angiographic restenosis or to dynamic constriction of any epicardial coronary segment. Therefore, inappropriate small coronary vessel constriction responsive to nitrates should be considered as a possible alternative explanation.

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 TM “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 “finger-print” 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. Differences in determining the absolute dimensions of coronary lesions could result from different catheters being used as scaling devices, and study designs using this approach should take this potential source of error into account.

Patterns in visual interpretation of coronary arteriograms as detected by quantitative coronary arteriography

In part 1 of a three-part study, 14 novice readers and 6 experienced cardiologists interpreted phantom images of known stenosis severity. No difference between the interpretations of experienced and novice readers was detectable. Visual estimates of “moderately” severe stenosis were 30% higher than actual percent diameter stenosis.In part 2 of the study, visual interpretation of percent diameter stenosis from 212 stenoses on 241 arteriograms was compared with quantitative coronary arteriographic assessment. The visual analysis overestimated disease severity in arteries with ≥50% diameter stenosis (except for right coronary lesions) and underestimated severity in all arteries with <50% diameter stenosis. Of the 241 arteriograms, 40 had quantitative and visual analysis of all three coronary arteries for assessment of significant disease. In only 62% of the cases did visual and quantitative methods agree on the presence of severe disease; visual estimates diagnosed significantly (p < 0.05) more three-vessel disease.In part 3 of the study, comparison of percent diameter stenosis by visual estimate with quantitative coronary arteriographic assessment before and after balloon angioplasty of 38 stenoses showed that visual interpretation significantly (p < 0.001) overestimated initial lesion severity and underestimated stenosis severity after angioplasty.

Coronary Artery Stenosis

Anatomic and functional characteristics of coronary artery stenosis physiology of coronary circulation methods for pressure-flow analysis and arteriography interactions with the coronary vascular bed phasic pressure flow and fluid dynamic analysis phasic pressure flow and arteriographic geometry collapsing stenoses coronary flow reserve quantitative coronary arteriography reversal by risk factor modication positron emission tomography of the heart prinicples of cardiac PET PET perfusion imaging quantitation of PET perfusion images coronary collateral function assessed by PET assessing myocardial infarction, ischemia and viability PET compared to other imaging modalities accuracy and performance of the positron scanner economics of cardiac PET radiation burden, facilities and regulatory status clinical case studies with PET.

Geometric Quantitative Coronary Arteriography

The application of dual energy (DE) subtraction techniques to quantitative coronary arteriography (QCA) has the advantage of removing the tissue signal surrounding the vessel profile. We have compared the performance of two geometric QCA algorithms on DE-subtracted and -unsubtracted images to determine, for each, if DE subtraction is advantageous. The two algorithms under study were an edge detection algorithm and a Fourier analysis-based algorithm. For each algorithm, linear regression analysis was performed of measured cross-sectional area (CSA) versus actual CSA of coronary vessel phantoms. The edge detection algorithm was found to have improved precision (P less than .05) when applied to the DE-subtracted images. The Fourier analysis algorithm, however, was not effected by the DE subtraction. Among the unsubtracted image results, the Fourier measurements were more accurate (P less than .05) than the edge detection measurements. We conclude that the benefits to edge detection QCA of DE tissue subtraction outweigh the disadvantages of increased image noise and possible misregistration artifacts. However, the Fourier algorithm is relatively insensitive to tissue signal variations.

Comparison of technetium-99m teboroxime tomography with automated quantitative coronary arteriography and thallium-201 tomographic imaging

Technetium-99m (Tc-99m) teboroxime is a new perfusion tracer that is highly extracted and rapidly cleared by the myocardium. To determine the feasibility of Tc-99m teboroxime imaging in the diagnosis of patients with suspected coronary artery disease, 30 patients underwent single photon emission computed tomography imaging with Tc-99m teboroxime (25.2 +/- 1 mCi) at peak exercise and again 60 min later at rest. All patients underwent either a thallium stress test (n = 26) or automated quantitative coronary arteriography (n = 25), or both, without intervening revascularization or infarction. Images were reviewed by two investigators who had no knowledge of clinical data. Coronary lesions with greater than or equal to 50% diameter narrowing by quantitative coronary arteriography were considered significant. Both thallium and Tc-99m teboroxime detected disease in all patients with two or three vessel disease. One vessel disease was detected with Tc-99m teboroxime in 9 of 10 patients and with thallium in 8 of 10 (p = NS). In patients without angiographically significant disease. Tc-99m teboroxime demonstrated normal perfusion in six of eight patients and thallium in three of five (p = NS). Overall, when presence or absence of disease detected by Tc-99m teboroxime or thallium was compared with quantitative coronary arteriography, there was no difference between Tc-99m teboroxime and thallium. These results suggest that Tc-99m teboroxime is comparable to thallium as an imaging agent. The rapid biologic half-life, 5.3 min, allows studies to be completed in 60 to 90 min.

Quantitative coronary arteriographic methods in the interventional catheterization laboratory: An update and perspective

Recent research advances in the area of quantitative coronary arteriography are described with respect to their potential role in assessing the effects of interventional therapy and monitoring the restenosis process. Specific areas emphasized are the importance of quantitative arteriography and absolute measures of arterial dimension in monitoring restenosis, the development of a computerized method for measuring lesion roughness, the potential role of measuring stenosis flow reserve based on component analysis principles, limitations of direct measures of myocardial flow reserve using a digital angiographic method and cautionary notes about clinical applications of videodensitometry. The current use of radiography and quantitative measures in limiting arterial injury are briefly reviewed. Finally, a perspective is put forth on the need to develop complementary roles for endovascular echocardiography and angioscopy with existing radiographic imaging technology.

Advantages and limitations of two software calipers in quantitative coronary arteriography

Software calipers allowing the measurement of the distances between pairs of manually defined picture elements in digitized images may be useful tools for a rapid assessment of the morphology of coronary vessels, e.g. for choosing the appropriate balloon or stent sizes before or during cardiac intervention procedures. In this paper we have studied extensively the advantages and limitations of two manual software calipers--one developed for a PC-based cinefilm analysis workstation, the other for the Philips DCI system. Based on analyses of a perspex vessel phantom with 17 sectors of known size filled with different concentrations (50 and 100%) of the contrast agent and acquired at two kV-levels (68 and 92 kV), it was found that the cinefilm approach is characterized by a very small overall (averaged over te data from three observers) systematic overestimation of 0.03 mm, and the DCI system by a systematic underestimation of 0.07 mm; the worst case accuracy value for an individual observer on frames with 100% contrast dye concentration was 0.20 mm for cinefilm, and -0.34 mm for the DCI, respectively. The overall variabilities in the measurements (precision) were almost identical for the two approaches (overall 0.07 and 0.08 mm for the cinefilm and digital approaches, respectively, and worst case for individual observers on the 100% contrast frames, 0.16 and 0.13 mm, respectively. Inverting the images (bright or dark contrast containing structures) of the phantom at 100% contrast concentration and acquired at 62 kV had no significant effect on the results obtained with the cinefilm analysis system (overall accurary -0.12 mm for both situations), whereas it had on the results from the DCI system (overall accuracies -0.29 (dark vessels on bright background) and -0.08 mm (bright vessels on dark background), respectively). Enhancing the digital images on the DCI with unsharp masking techniques did not significantly influence the measurement accuracy and precision. Finally, it was found that woven dacron, polyurethane and polyvinylchloride catheters filled with 100% contrast dye can be measured with an overall accuracy of better than 0.13 mm on the DCI system. On the PC-based system the woven dacron and polyvinylchloride catheters would result in an overall accuracy better than 0.17 mm, and the polyurethane catheter better than 0.30 mm. The evaluation study has made clear that the nylon catheter should not be applied in QCA-studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Absolute Cross-Sectional Area Measurements in Quantitative Coronary Arteriography by Dual-Energy DSA

Recent studies have emphasized the limitations of conventional coronary angiography. These limitations include the lack of correlation between the severity of coronary stenosis as estimated from coronary angiograms and the actual severity of stenotic lesions measured in postmortem hearts. As a result, attempts have been made to quantitate luminal dimension more precisely. The application of quantitative digital subtraction angiography (DSA) in the assessment of coronary artery lesion dimension has been limited by cardiac and respiratory motion artifacts. We have reported previously on a motion-immune dual-energy (DE) cardiac mode in which kVp and filtration are switched at 30 Hz. To assess the potential advantages of a videodensitometric technique for quantification of absolute vessel cross-sectional area (CSA), three different quantitative coronary arteriography (QCA) algorithms were compared. The three algorithms under comparison were a videodensitometric (V) algorithm, which does not require any geometric assumption for absolute vessel CSA measurement, and videodensitometric (VC) and edge detection (ED) algorithms, which do require the assumption of circular cross-section for CSA measurements. A cylindrical vessel phantom (0.5-4.75 mm in diameter) and a crescentic vessel phantom, producing 25% to 90% area stenosis, were imaged over the chest of a humanoid phantom. The low- and high-energy images were corrected for scatter and veiling glare before energy subtraction. For CSA measurements in crescentic vessel phantoms, the V algorithm produced significantly improved results (slope = 0.87, intercept = 0.51 mm2, r = .95) when compared to the VC (slope = 1.05, intercept = 4.19 mm2, r = .75) and the ED (slope = 1.57, intercept = 5.21 mm2, r = .60) algorithms.

Basic structure-function relations of the coronary vascular tree — The basis of quantitative coronary arteriography for diffuse coronary artery disease

Basic structure-function relations of the coronary vascular tree — The basis of quantitative coronary arteriography for diffuse coronary artery disease