Bruining, N.

The diagnostic value of intracoronary optical coherence tomography (Article)

2011-07-11T00:00:00Z

Optical coherence tomography (OCT) is a novel light-based imaging modality for application in the coronary circulation. Compared to conventional intravascular ultrasound, OCT has a ten-fold higher image resolution. This advantage has seen OCT successfully applied in the assessment of atherosclerotic plaque, stent apposition, and tissue coverage, heralding a new era in intravascular coronary imaging. The present article discusses the diagnostic value of OCT, both in cardiovascular research as well as in potential clinical application. The unparalleled high image resolution and strong contrast between the coronary lumen and the vessel wall structure enable fast and reliable image interpretation. OCT makes it possible to visualize the presence of atherosclerotic plaque in order to characterize the structure and extent of coronary plaque and to quantify lumen dimensions, as well as the extent of lumen narrowing, in unprecedented detail. Based on optical properties, OCT is able to distinguish different tissue types, such as fibrous, lipid-rich, necrotic, or calcified tissue. Furthermore, OCT is able to cover the visualization of a variety of features of atherosclerotic plaques that have been associated with rapid lesion progression and clinical events, such as thin cap fibroatheroma, fibrous cap thickness, dense macrophage infiltration, and thrombus formation. These unique features allow the use of OCT to assess patients with acute coronary syndrome and to study the dynamic nature of coronary atherosclerosis in vivo and over time. This permits new insights into plaque progression, regression, and rupture, as well as the study of effects of therapies aimed at modulating these developments. Today's OCT technology allows high detail resolution as well as fast and safe clinical image acquisition. These unique features have established OCT as the gold standard for the assessment of coronary stents. This technique makes it possible to study stent expansion, peri-procedural vessel trauma, and the interaction of the stent with the vessel wall down to the level of individual stent struts, both acutely as well as in the long term, where it is has proven extremely sensitive to the detection of even minor amounts of tissue coverage. These qualities render OCT indispensable to addressing vexing clinical questions such as the relationship of drug-eluting stent deployment, vascular healing, the true time course of endothelial stent coverage, and late stent thrombosis. This may also better guide the optimal duration of dual anti-platelet therapy that currently remains unclear and relatively empirical. In the future, OCT might emerge, parallel to its undisputed position in research, as the tool of choice in all clinical scenarios where angiography is limited by its nature as a two-dimensional luminogram.

IVUS-based imaging modalities for tissue characterization: similarities and differences (Article)

2011-02-17T00:00:00Z

Gray-scale intravascular ultrasound (IVUS) is the modality that has been established as the golden standard for in vivo imaging of the vessel wall of the coronary arteries. The use of IVUS in clinical practice is an important diagnostic tool used for quantitative assessment of coronary artery disease. This has made IVUS the de-facto invasive imaging method to evaluate new interventional therapies such as new stent designs and for atherosclerosis progression-regression studies. However, the gray-scale representation of the coronary vessel wall and plaque morphology in combination with the limited resolution of the current IVUS catheters makes it difficult, if not impossible, to identify qualitatively (e.g. visually) the plaque morphology similar as that of histopathology, the golden standard to characterize and quantify coronary plaque tissue components. Meanwhile, this limitation has been partially overcome by new innovative IVUS-based post-processing methods such as: virtual histology IVUS (VH-IVUS, Volcano Therapeutics, Rancho Cordova, CA, USA), iMAP-IVUS (Bostoc Scientific, Santa Clara, CA, USA), Integrated Backscatter IVUS (IB-IVUS) and Automated Differential Echogenicity (ADE).

Morphological and functional evaluation of the bioresorption of the bioresorbable everolimus-eluting vascular scaffold using IVUS, echogenicity and vasomotion testing at two year follow-up: a patient level insight into the ABSORB A clinical trial (Article)

2010-12-01T00:00:00Z

The aim of this study was to describe vaso-reactivity (by Acetylcholine and Methergine tests) at 2 year follow-up in parallel with the individual changes in the echogenicity characteristics of the polymer struts of the everolimus eluting bioresorbable vascular scaffold (BVS), from post-treatment to 2 year follow-up, in patients enrolled in the ABSORB Cohort A study. Intravascular ultrasound assessment was performed with a phased array catheter (EagleEye, Volcano Corporation, Cordova, CA, USA) with automated pullback at 0.5 mm per second. The % ratio at 6 months and 2 years [(Scaffold Area post PCI- Lumen Area)/Scaffold Area post PCI] was calculated as a measure of scaffold shrinkage. The % change of hyperechogenicity was defined as: ([post-procedural hyperechogenicity] - [2 year follow up hyperechogenicity])/[post-procedural hyperechogenicity]) × 100. The vasomotion test with intracoronary acetylcholine (10-6M) or intravenous methergine (0.4 mg) was performed at 2 years. Overall nine patients received all these analyses and were enrolled in the present analysis. A 50-96% reduction in hyperechogenicity was observed between baseline and 2 years, which corresponded to a change in vasoreactivity between 2 and 22%. A vasoconstriction of the scaffolded segment was observed in the 5 patients, who underwent the methergine test, with a mean decrease in lumen diameter after methergine of 9 ± 7% (P = 0.06), while vasodilatation occurred in the 4 patients who underwent the acetylcholine test with a mean increase in lumen diameter after acetylcholine of 8 ± 5% (P = 0.125). Bioresorption of the BVS is accompanied by re-establishment of both endothelial and non-endothelial dependent vasomotion.

Lumen enhancement influences absolute noncalcific plaque density on multislice computed tomography coronary angiography: Ex-vivo validation and in-vivo demonstration (Article)

2010-05-01T00:00:00Z

Aim: The purpose of this study was to define the in-vitro and in-vivo effects of intracoronary enhancement on the absolute density values of coronary plaques during multislice computed tomography. Methods: We studied seven ex-vivo left coronary artery specimens surrounded by olive oil and filled with isotonic saline and four solutions with decreasing dilutions of contrast material: control (isotonic saline), 1/200, 1/80, 1/50, and 1/20. The multislice computed tomography protocol was: slice/collimation 32 × 2 × 0.6 mm and rotation time 330 ms. The attenuation (Hounsfield units) value of atherosclerotic plaques was measured for each dilution in lumen, plaque (noncalcified coronary wall thickening), calcium, and surrounding oil. In-vivo assessment was performed in 12 patients (nine men; mean age 58.7 ± 9.9 years) who underwent two subsequent multislice computed tomography scans (arterial and delayed) after intravenous administration of a single bolus of contrast material. The attenuation values of lumen and plaques during arterial and delayed computed tomography were compared. The results were compared with one-way analysis of variance and correlated with Pearson's test. Results: Mean lumen (45 ± 38-669 ± 151 HU) and plaque (11 ± 35-101 ± 72 HU) attenuation differed significantly (P < 0.001) among the different dilutions. The attenuation of lumen and plaque of coronary plaques showed moderate correlation (r = 0.54, P < 0.001). The mean attenuation value in vivo for the arterial and delayed phase scans differed significantly (P < 0.001) for lumen (325 ± 70 and 174 ± 46 HU, respectively) and plaque (138 ± 71 and 100 ± 52 HU, respectively). Conclusion: Coronary plaque attenuation values are significantly modified by differences in lumen contrast densities both ex vivo and in vivo. This should be taken into account when considering the distinction between lipid and fibrous plaques.

Monitoring in vivo absorption of a drug-eluting bioabsorbable stent with intravascular ultrasound-derived parameters: A feasibility study (Article)

2010-03-01T00:00:00Z

Objectives: The aim of this study was to investigate the feasibility of using quantitative differential echogenicity to monitor the in vivo absorption process of a drug-eluting poly-l-lactic-acid (PLLA) bioabsorbable stent (BVS, Abbott Vascular, Santa Clara, CA). Background: A new bioabsorbable, balloon-expanded coronary stent was recently evaluated in a first-in-man study. Little is known about the absorption process in vivo in diseased human coronary arteries. Methods: In the ABSORB (Clinical Evaluation of the BVS everolimus eluting stent system) study, 30 patients underwent treatment with the BVS coronary stent system and were examined with intracoronary ultrasound (ICUS) after implantation, at 6 months and at 2-year follow-up. Quantitative ICUS was used to measure dimensional changes, and automated ICUS-based tissue composition software (differential echogenicity) was used to quantify plaque compositional changes over time in the treated regions. Results: The BVS struts appeared as bright hyperechogenic structures and showed a continuous decrease of their echogenicity over time, most likely due to the polymer degradation process. In 12 patients in whom pre-implantation ICUS was available, at 2 years the percentage-hyperechogenic tissue was close to pre-implantation values, indicating that the absorption process was either completed or the remaining material was no longer differentially echogenic from surrounding tissues. Conclusions: Quantitative differential echogenicity is a useful plaque compositional measurement tool. Furthermore, it seems to be valuable for monitoring the absorption process of bioabsorbable coronary stents made of semi-crystalline polymers.

Fully automatic three-dimensional quantitative analysis of intracoronary optical coherence tomography: Method and validation (Article)

2009-12-01T00:00:00Z

Objectives and background: Quantitative analysis of intracoronary optical coherence tomography (OCT) image data (QOCT) is currently performed by a time-consuming manual contour tracing process in individual OCT images acquired during a pullback procedure (frame-based method). To get an efficient quantitative analysis process, we developed a fully automatic three-dimensional (3D) lumen contour detection method and evaluated the results against those derived by expert human observers. Methods: The method was developed using Matlab (The Mathworks, Natick, MA). It incorporates a graphical user interface for contour display and, in the selected cases where this might be necessary, editing. OCT image data of 20 randomly selected patients, acquired with a commercially available system (Lightlab imaging, Westford, MA), were pulled from our OCT database for validation. Results: A total of 4,137 OCT images were analyzed. There was no statistically significant difference in mean lumen areas between the two methods (5.03 ± 2.16 vs. 5.02 ± 2.21 mm2; P = 0.6, human vs. automated). Regression analysis showed a good correlation with an r value of 0.99. The method requires an average 2-5 sec calculation time per OCT image. In 3% of the detected contours an observer correction was necessary. Conclusion: Fully automatic lumen contour detection in OCT images is feasible with only a select few contours showing an artifact (3%) that can be easily corrected. This QOCT method may be a valuable tool for future coronary imaging studies incorporating OCT.

Coronary calcium significantly affects quantitative analysis of coronary ultrasound: Importance for atherosclerosis progression/regression studies (Article)

2009-09-01T00:00:00Z

BACKGROUND: Coronary atherosclerosis is a dynamic process, which progresses differently in coronary segments containing noncalcified or calcified plaques. This may have implications for the study of the effects of therapy on progression/regression. OBJECTIVE: To test this hypothesis, we performed a post-hoc analysis on data of a randomized trial in which perindopril treatment was compared with placebo on progression/regression of atherosclerosis with regard to the degree of calcification. METHODS AND RESULTS: The intracoronary ultrasound data of 118 patients, who were enrolled in the multicentre, double-blinded randomized trial (PERSPECTIVE), were analysed. Vessel, lumen and plaque areas were measured in 711 5-mm-long matched coronary segments (perindopril 360, placebo 351). Each individual intracoronary ultrasound cross-section was binary labelled for the presence of calcium (yes/no), and the degree of calcium was assessed as a percentage of length. The segments were classified into three groups: 0-25, 25-50 and 50-100% (percentage of length) calcification. Coronary plaques with no or little calcium (0-25%) regressed on perindopril and did not change on placebo (-0.33±1.74 vs. -0.03±1.66, respectively; P=0.04). Plaques containing moderate calcium (group 25-50%) did not change and plaques with severe amounts of calcification (group 50-100%) equally progressed. CONCLUSION: Noncalcified plaques may be amenable to regression with ACE inhibitor treatment. The method, which considers the amount of calcium content in a plaque, may lead to new insights for quantitative analysis of the effects of therapy in progression/regression studies of atherosclerosis.

A bioabsorbable everolimus-eluting coronary stent system (ABSORB): 2-year outcomes and results from multiple imaging methods (Article)

2009-03-18T00:00:00Z

Background: Drug-eluting metallic coronary stents predispose to late stent thrombosis, prevent late lumen vessel enlargement, hinder surgical revascularisation, and impair imaging with multislice CT. We assessed the safety of the bioabsorbable everolimus-eluting stent (BVS). Methods: 30 patients with a single de-novo coronary artery lesion were followed up for 2 years clinically and with multiple imaging methods: multislice CT, angiography, intravascular ultrasound, derived morphology parameters (virtual histology, palpography, and echogenicity), and optical coherence tomography (OCT). Findings: Clinical data were obtained from 29 of 30 patients. At 2 years, the device was safe with no cardiac deaths, ischaemia-driven target lesion revascularisations, or stent thromboses recorded, and only one myocardial infarction (non-Q wave). 18-month multislice CT (assessed in 25 patients) showed a mean diameter stenosis of 19% (SD 9). At 2-year angiography, the in-stent late loss of 0·48 mm (SD 0·28) and the diameter stenosis of 27% (11) did not differ from the findings at 6 months. The luminal area enlargement on OCT and intravascular ultrasound between 6 months and 2 years was due to a decrease in plaque size without change in vessel size. At 2 years, 34·5% of strut locations presented no discernible features by OCT, confirming decreases in echogenicity and in radiofrequency backscattering; the remaining apparent struts were fully apposed. Additionally, vasomotion occurred at the stented site and adjacent coronary artery in response to vasoactive agents. Interpretation: At 2 years after implantation the stent was bioabsorbed, had vasomotion restored and restenosis prevented, and was clinically safe, suggesting freedom from late thrombosis. Late luminal enlargement due to plaque reduction without vessel remodelling needs confirmation. Funding: Abbott Vascular (USA).

A histological "Fly-Through" of a diseased coronary artery (Article)

2009-03-01T00:00:00Z

Late Stent Recoil of the Bioabsorbable Everolimus-Eluting Coronary Stent and its Relationship With Plaque Morphology (Article)

2008-11-11T00:00:00Z

Objectives: This study sought to evaluate late recoil of a novel bioabsorbable everolimus-eluting coronary stent (BVS), which is composed of a poly-L-lactic acid backbone, coated with a bioabsorbable polymer containing everolimus. Background: Little is known about the mechanical behavior of bioabsorbable polymer stents after deployment in diseased human coronary arteries. Methods: The study population consisted of 16 patients, who were treated with elective BVS implantation for single de novo native coronary artery lesions and were followed at 6 months. All patients underwent an intravascular ultrasound examination at post-procedure and follow-up. A total of 484 paired cross-sectional areas (CSAs) were acquired and analyzed. Late absolute stent recoil was defined as stent area at post-procedure (X) - stent area at follow-up (Y). Late percent stent recoil was defined as (X - Y)/X × 100. In each CSA, plaque morphology was assessed qualitatively and classified as calcific, fibronecrotic, or fibrocellular plaque. Results: Late absolute and percent recoil of the BVS was 0.65 ± 1.71 mm2(95% confidence interval [CI]: 0.49 to 0.80 mm2) and 7.60 ± 23.3% (95% CI: 5.52% to 9.68%). Calcified plaques resulted in significantly less late recoil (0.20 ± 1.54 mm2and 1.97 ± 22.2%) than fibronecrotic plaques (1.03 ± 2.12 mm2and 12.4 ± 28.0%, p = 0.001 and p = 0.001, respectively) or fibrocellular plaque (0.74 ± 1.48 mm2and 8.90 ± 19.8%, p = 0.001 and p = 0.001, respectively). Conclusions: The BVS shrank in size during the follow-up period. The lesion morphology of stented segments might affect the degree of late recoil of the BVS. (ABSORB Everolimus Eluting Coronary Stent System First in Man Clinical Investigation; NCT00300131).

A novel approach for quantitative analysis of intracoronary optical coherence tomography: High inter-observer agreement with computer-assisted contour detection (Article)

2008-08-01T00:00:00Z

Objective: This study aims to examine observer-related variability of quantitative optical coherence tomography (OCT) derived measurements from both in vitro and in vivo pullback data. Background: Intravascular OCT is a new imaging modality using infrared light and offering 10 times higher image resolution (15 μm) compared to intravascular ultrasound. The quantitative analysis of in vivo intracoronary OCT imaging is complicated by the presence of blood, motion artifacts and the large quantity of information that has to be processed. Methods: We developed a standardized, automated quantification process for intracoronary OCT pullback data with inter-observer variability assessed both in vitro by using postmortem human coronary arteries and in vivo by studying simple and complex coronary pathology and outcomes following stent implantation. The consensus between measurements by two observers was analyzed using the intraclass and interclass correlation coefficient and the reliability coefficients. Bland-Altman plots were generated to assess the relationship between variability and absolute measurements. Results: In vitro OCT assessment was performed in nine postmortem coronary arteries. The time needed for semiautomated contour detection of a 15-mm long coronary segment was ∼40 min. The absolute and relative difference between lumen area measurements derived from two observers was low [0.02 ± 0.10 mm2; (0.3 ± 0.5)% respectively] with excellent correlation confirmed by linear regression analysis (R2= 0.99; P < 0.001). Similarly, in vivo measurements demonstrated a high correlation with the main source of inter-observer variation occurring as a result of coronary dissection and motion artifact. The absolute and relative difference between measurements were 0.11 ± 0,33 mm2(1.57 ± 0.05)% for lumen area (R2= 0.98; P < 0.001), 0.17 ± 0.68 mm2(1.44 ± 0.08)% for stent area (R2= 0.94; P < 0.001), and 0.26 ± 0.72 mm2(14.05 ± 0.37)% for neointimal area (R2= 0.78; P < 0.001). Conclusions: Highly accurate computer-assisted quantitative analysis of intracoronary OCT pullbacks is feasible with low inter-observer variability. The presented approach allows for observer independent analysis of detailed vessel structures, and may be a valuable tool for future longitudinal studies incorporating OCT,

Coronary plaque composition as assessed by greyscale intravascular ultrasound and radiofrequency spectral data analysis (Article)

2008-06-12T00:00:00Z

Objectives: (i) To explore the relation between greyscale intravascular ultrasound (IVUS) plaque qualitative classification and IVUS radiofrequency data (RFD) analysis tissue types; (ii) to evaluate if plaque composition as assessed by RFD analysis can be predicted by visual assessment of greyscale IVUS images. Methods: In 120 IVUS-RFD cross-sections, a sector of the plaque with homogenous tissue composition (e.g., fibrous, fibrofatty, necrotic core, and dense calcium) was selected. Two experienced observers analyzed twice the corresponding greyscale IVUS images to: (1) classify the selected sectors according to greyscale IVUS plaque type classification and (2) predict the tissue type expected in the sector by RFD analysis. Results: In the greyscale IVUS plaque type classification, the observers agreed in 90/120 sectors (κ = 0.64). Calcified, soft and mixed plaques by greyscale IVUS classification were mainly composed of dense calcium, fibrofatty, and necrotic core, respectively, in the RFD analysis. The plaques classified in greyscale IVUS as fibrous were actually fibrous tissue by IVUS RFD in only 30% of the cases. Overall, high interobserver variability in the prediction of RFD results by visual assessment of greyscale IVUS images (κ = 0.23 for observer 1 and 0.55 for observer 2) was found. Sensitivities for detection of calcified tissue and NC by greyscale IVUS visual assessment were 88% and 58%, respectively. Conclusions: High interobserver variability in the prediction of tissue type by visual assessment of greyscale IVUS images was observed. This underlines the need of quantitative methods for the analysis of the ultrasound characteristics of coronary plaque components.

Quantification of coronary plaque by 64-slice computed tomography: A comparison with quantitative intracoronary ultrasound (Article)

2008-05-01T00:00:00Z

BACKGROUND: Noninvasive assessment of coronary atherosclerotic plaque may be useful for risk stratification and treatment of atherosclerosis. MATERIALS AND METHODS: We studied 47 patients to investigate the accuracy of coronary plaque volume measurement acquired with 64-slice multislice computed tomography (MSCT), using newly developed quantification software, when compared with quantitative intracoronary ultrasound (QCU). Quantitative MSCT coronary angiography (QMSCT-CA) was performed to determine plaque volume for a matched region of interest (regional plaque burden) and in significant plaque defined as a plaque with ≥50% area obstruction in QCU, and compared with QCU. Dataset with image blurring and heavy calcification were excluded from analysis. RESULTS: In 100 comparable regions of interest, regional plaque burden was highly correlated (coefficient r = 0.96; P < 0.001) between QCU and QMSCT-CA, but QMSCT-CA overestimated the plaque burden by a mean difference of 7 ± 33 mm (P = 0.03). In 76 significant plaques detected within the regions of interest, plaque volume determined by QMSCT-CA was highly correlated (r = 0.98; P < 0.001) with a slight underestimation of 2 ± 17 mm (P = not significant) when compared with QCU. Calcified and mixed plaque volume was slightly overestimated by 4 ± 19 mm (P = ns) and noncalcified plaque volume was significantly underestimated by 9 ± 11 mm (P < 0.001) with QMSCT-CA. Overall, the limits of agreement for plaque burden/volume measurement between QCU and QMSCT-CA were relatively large. Reproducibility for the measurements of regional plaque burden with QMSCT-CA was good, with a mean intraobserver and interobserver variability of 0% ± 16% and 4% ± 24%, respectively. CONCLUSIONS: Quantification of coronary plaque within selected proximal or middle coronary segments without image blurring and heavy calcification with 64-slice CT was moderately accurate with respect to intravascular ultrasound and demonstrated good reproducibility. Further improvement in CT resolution is required for more reliable measurement of coronary plaques using quantification software.

Three-dimensional and quantitative analysis of atherosclerotic plaque composition by automated differential echogenicity (Article)

2007-12-01T00:00:00Z

Objective: To validate automated and quantitative three-dimensional analysis of coronary plaque composition using intracoronary ultrasound (ICUS). Background: ICUS displays different tissue components based on their acoustic properties in 256 grey-levels. We hypothesised that computer-assisted image analysis (differential echogenicity) would permit automated quantification of several tissue components in atherosclerotic plaques. Methods and Results: Ten 40-mm-long left anterior descending specimens were excised during autopsy of which eight could be successfully imaged by ICUS. Histological sections were taken at 5 mm intervals and analyzed. Since most of the plaques were calcified and having a homogeneous appearance, one specimen with a more heterogeneous composition was further examined: at each interval of 5 mm, 15 additional sections (every 100 μm) were evaluated. Plaques were scored for echogenicity against the adventitia: brighter (hyperechogenic) or less bright (hypoechogenic). Areas of hypoechogenicity correlated with the presence of smooth muscle cells. Areas of hyperechogenicity correlated with presence of collagen, and areas of hyperechogenicity with acoustic shadowing correlated with calcium. None of these comparisons showed statistical significant differences. Conclusion: This ex vivo feasibility study shows that automated three-dimensional differential echogenicity analysis of ICUS images allows identification of different tissue types within atherosclerotic plaques. This technology may play a role as an additional tool in longitudinal studies to trace possible changes in plaque composition.

Effect of perindopril on coronary remodelling: Insights from a multicentre, randomized study (Article)

2007-10-01T00:00:00Z

Aims: This study sought to evaluate the effect of perindopril in coronary remodelling. Methods and results: In this sub-study of a double-blind, multicentre trial, patients without clinical evidence of heart failure were randomized to perindopril 8 mg/day or placebo for at least 3 years and IVUS investigation was performed at both time-points. Positive and negative remodelling were defined as a relative increase (positive remodelling) or decrease (negative remodelling) of the mean vessel cross-sectional area (CSA) > 2 SD of the mean intra-observer difference. A total of 118 matched evaluable IVUS (711 matched 5 mm segments) were available at follow-up. After a median follow-up of 3.0 (inter-quartile range 1.9, 4.1) years, there was no significant difference in the change of plaque CSA between perindopril (360 segments) and placebo (351 segments) groups, P = 0.27. Conversely, the change in vessel CSA was significantly different between groups (perindopril -0.18 ± 2.4 mm2vs. placebo 0.19 ± 2.4, P = 0.04). Negative remodelling occurred more frequently in the perindopril than in the placebo group (34 vs. 25%, P = 0.01). In addition, the placebo group showed a larger, although not significant, mean remodelling index (RI) than the perindopril group (1.03 ± 0.2 vs. 1.00 ± 0.2, P = 0.06). The temporal change in vessel dimensions assessed by the RI was significantly correlated with the change in plaque dimensions (r = 0.48, P < 0.0001). Conclusion: In this sub-analysis of a multicentre, controlled study, long-term administration of perindopril was associated with a constrictive remodelling pattern without affecting the lumen.

Long-Term Effect of Perindopril on Coronary Atherosclerosis Progression (from the PERindopril's Prospective Effect on Coronary aTherosclerosis by Angiography and IntraVascular Ultrasound Evaluation [PERSPECTIVE] Study) (Article)

2007-07-15T00:00:00Z

The multicenter EUROPA trial of 12,218 patients showed that perindopril decreased adverse clinical events in patients with established coronary heart disease. The PERSPECTIVE study, a substudy of the EUROPA trial, evaluated the effect of perindopril on coronary plaque progression as assessed by quantitative coronary angiography and intravascular ultrasound (IVUS). In total 244 patients (mean age 57 years, 81% men) were included. Evaluable paired quantitative coronary angiograms were obtained from 96 patients randomized to perindopril and from 98 patients to placebo. Concomitant treatment at baseline consisted of aspirin (90%), lipid-lowering agents (70%), and β blockers (60%). The primary and secondary end point was the difference of minimum and mean lumen diameters (quantitative coronary angiography) or mean plaque cross-sectional area (IVUS) measured at baseline and 3-year follow-up between the perindopril and placebo groups. After a median follow-up of 3.0 years (range 1.9 to 4.1), no differences in change in quantitative coronary angiographic or IVUS measurements were detected between the perindopril and placebo groups (minimum and mean luminal diameters -0.07 ± 0.4 vs -0.02 ± 0.4 mm, p = 0.34; mean luminal diameter -0.05 ± 0.2 vs -0.05 ± 0.3 mm, p = 0.89; mean plaque cross-sectional area -0.18 ± 1.2 vs -0.02 ± 1.2 mm2, p = 0.48). In conclusion, we found no progression in coronary artery disease by quantitative coronary angiography and IVUS with long-term administration of perindopril or placebo, possibly because most patients were on concomitant treatment with a statin.

Intravascular Ultrasound Comparison of Sirolimus-Eluting Stent Versus Bare Metal Stent Implantation in Diseased Saphenous Vein Grafts (from the RRISC [Reduction of Restenosis In Saphenous Vein Grafts With Cypher Sirolimus-Eluting Stent] Trial) (Article)

2007-07-01T00:00:00Z

The randomized Reduction of Restenosis In Saphenous Vein Grafts with Cypher Sirolimus-Eluting Stent trial compared angiographic outcomes of sirolimus-eluting stents (SESs) versus bare metal stents (BMSs) in saphenous vein grafts (SVG). Using intravascular ultrasound (IVUS) performed during 6-month follow-up angiography, we compared the vascular effects of the 2 types of stent on SVGs. Of 75 patients (96 lesions) included, 59 patients underwent IVUS in 61 SVGs; 29 patients received 40 SESs for 34 lesions, and 30 patients received 42 BMSs for 39 lesions. IVUS parameters (diameters, areas, and volumes) were compared in the 2 groups. A specific analysis was performed for overlapping SESs. Median neointimal volume was 1.3 mm3(interquartile range 0 to 13.1) in SESs versus 24.5 (7.8 to 39.5) in BMSs (p <0.001). Minimal incomplete stent apposition was detected at only 3 stent edges (2 BMSs, 1 SES) next to ectatic regions of the SVG. Compared with single SESs, overlapping SESs showed significant increases in neointimal reaction, with a neointimal volume of 0.6 mm3/mm of stent (0.1 to 1.8) versus 0 (0 to 0.4) in single SESs (p = 0.03), and this phenomenon was mainly localized in overlapping SES segments, where neointimal volume per millimeter of stent was 1.1 mm3/mm (0.6 to 4.4) versus 0 (0 to 1.3) in nonoverlapping segments (p = 0.05). In conclusion, SESs effectively inhibit neointimal hyperplasia volume compared with BMSs in diseased vein grafts, without evidence of increased incomplete apposition risk. The neointimal response to overlapping SES layers seems higher than to a single SES layer.

Influence of convolution filtering on coronary plaque attenuation values: Observations in an ex vivo model of multislice computed tomography coronary angiography (Article)

2007-07-01T00:00:00Z

Attenuation variability (measured in Hounsfield Units, HU) of human coronary plaques using multislice computed tomography (MSCT) was evaluated in an ex vivo model with increasing convolution kernels. MSCT was performed in seven ex vivo left coronary arteries sunk into oil followingthe instillation of saline (1/∞) and a 1/50 solution of contrast material (400 mgI/ml iomeprol). Scan parameters were: slices/ collimation, 16/0.75 mm; rotation time, 375 ms. Four convolution kernels were used: b30f-smooth, b36f-medium smooth, b46f-medium and b60f-sharp. An experienced radiologist scored for the presence of plaques and measured the attenuation in lumen, calcified and noncalcified plaques and the surrounding oil. The results were compared by the ANOVA test and correlated with Pearson's test. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. The mean attenuation values were significantly different between the four filters (p<0.0001) in each structure with both solutions. After clustering for the filter, all of the noncalcified plaque values (20.8±39.1, 14.2±35.8, 14.0±32.0, 3.2±32.4 HU with saline; 74.7±66.6, 68.2±63.3, 66.3±66.5, 48.5±60.0 HU in contrast solution) were significantly different, with the exception of the pair b36f-b46f, for which a moderate-high correlation was generally found. Improved SNRs and CNRs were achieved by b30f and b46f. The use of different convolution filters significantly modifief the attenuation values, while sharper filtering increased the calcified plaque attenuation and reduced the noncalcified plaque attenuation.

Reproducible coronary plaque quantification by multislice computed tomography (Article)

2007-05-01T00:00:00Z

Background: The aim of this study was to investigate reproducibility end accuracy of computer-assisted coronary plaque measurements by multislice computed tomography coronary angiography (QMSCT-CA). Methods and Results: Forty-sight patients undergoing MSCT-CA end coronary arteriography for symptomatic coronary artery disease and quantitative intravascular ultrasound (IVUS, QCU) were examined. Two investigators performed the QMSCT-CA twice end e third investigator performed the QCU, all blinded for each other's results. There was no difference found for the matched region of interest (ROI) lengths (QCU 29.4 ± 13 mm vs. QMSCT-CA 29.6 ± 13 mm, P = 0.6; total length = 1,400 mm). The comparison of volumetric measurements showed (lumen QCU 267 ± 139 mm3vs. mean QMSCT-CA 177 ± 91 mm3, P < 0.001; vessel 454 ± 194 mm3vs. 398 ± 187 mm3, P < 0.001; and plaque 189 ± 93 mm3vs. 222 ± 121 mm3; investigator 1, P = 0.02; and investigator 2, P = 0.07) significant differences. Automated lumen detection was also applied for QMSCT-CA (218 ± 112 mm3, P < 0.001 vs. QCU). The Interinvestigator variability measurements for QMSCT-CA showed no significant differences. Conclusion: QMSCT-CA systematically underestimates absolute coronary lumen- and vessel dimensions when compared with QCU. However, repeated measurements of coronary plaque by QMSCT-CA showed no statistically significant differences, although, the outcome showed a scattered result. Automated lumen detection for QMSCT-CA showed improved results when compered with those of human investigators.

Two-Year Serial Coronary Angiographic and Intravascular Ultrasound Analysis of In-Stent Angiographic Late Lumen Loss and Ultrasonic Neointimal Volume from the TAXUS II Trial (Article)

2007-03-01T00:00:00Z

Late loss has been used as a reliable surrogate end point for evaluation and differentiation of short-term performance of drug-eluting stents. This study investigated the consistency between angiographic and intravascular ultrasound (IVUS) outcomes of late lumen loss (late loss) and neointimal growth to measure restenotic plaque load in TAXUS and bare metal stents. The randomized TAXUS II trial evaluates the polymer-based paclitaxel-eluting TAXUS stent in slow- and moderate-release formulations. Serial angiographic and IVUS analyses were available in 155 event-free patients (bare metal stent, 74; TAXUS stent, 81) after the procedure, at 6 months, and at 2 years. For this subanalysis, quantitative coronary angiographic (QCA) and IVUS measurements were used to derive late loss and neointimal volume. From after the procedure to 6 months, quantitative coronary angiography and IVUS showed matching results for the 2 groups with significant decreases in late loss and neointimal volume in the TAXUS versus the control group. From 6 months to 2 years, QCA and IVUS measurements also showed results similar to those in the control group, demonstrating neointimal compaction over time. However, in the TAXUS group, QCA late loss showed a nonsignificant decrease from 6 months to 2 years, whereas IVUS neointimal volume increased. In conclusion, although QCA and IVUS results were similar over the first 6 months, long-term assessment of changes in restenotic plaque load showed discrepant findings for the TAXUS. These findings suggest the need for critical reevaluation of current end points and the use of more precise techniques to detect lumen and stent boundaries.

Non-invasive visualization of coronary atherosclerosis: State-of-art (Article)

2007-03-01T00:00:00Z

Coronary artery disease remains the leading cause of death in the Western world. Non-invasive coronary artery imaging challenges any diagnostic modality because the coronary arteries are small and tortuous, whereas cardiac contraction and respiration cause motion artifacts. Therefore, non-invasive coronary imaging requires high spatial and temporal resolution. This review discusses the feasible applications in coronary imaging of magnetic resonance imaging and multi-slice computed tomography (MSCT), which are currently the only non-invasive diagnostic modalities for direct coronary atherosclerosis imaging. Particular attention and focus is devoted to the potential indications and clinical impact of MSCT due to its fast development and the robust results recently reported. MSCT of the coronary arteries is a promising imaging modality for the assessment of the coronary lumen and wall.

Meta-Analysis of the Studies Assessing Temporal Changes in Coronary Plaque Volume Using Intravascular Ultrasound (Article)

2007-01-01T00:00:00Z

To assess the temporal effect of statin therapy on coronary atherosclerotic plaque volume measured by intravascular ultrasound (IVUS), we searched PubMed for eligible studies published between 1990 and January 2006. Inclusion criteria for retrieved studies were (1) IVUS volume analysis at baseline and follow-up and (2) statin therapy in ≥1 group of patients. All data of interest were abstracted in prespecified structured collection forms. Statistical analysis was performed with Review Manager 4.2. Random-effect weighted mean difference (WMD) was used as summary statistics for comparison of continuous variables. Nine studies of 985 patients (with 11 statin treatment arms) were selected. After a mean follow-up of 9.8 ± 4.9 months, we found a significant decrease in coronary plaque volume (WMD -5.77 mm3, 95% confidence interval -10.36 to -1.17, p = 0.01), with no significant heterogeneity across studies (p = 0.47). Prespecified subgroup analyses showed similar trends. Studies in which the achieved low-density lipoprotein (LDL) cholesterol level was <100 mg/dl showed a trend for plaque regression (WMD -7.88 mm3, 95% confidence interval -16.31 to 0.55, p = 0.07), whereas studies in which the achieved level of LDL cholesterol was ≥100 mg/dl, the trend was less evident (WMD -4.22 mm3, 95% confidence interval -10.27 to 1.82, p = 0.17). Plaque volume remained essentially unchanged in patients not treated with statins (WMD 0.13 mm3, 95% confidence interval -4.42 to 4.68, p = 0.96). In conclusion, statin therapy, particularly when achieving the target LDL level, appears to promote a significant regression of coronary plaque volume as measured by IVUS.

Incomplete stent apposition after implantation of paclitaxel-eluting stents or bare metal stents: insights from the randomized TAXUS II trial. (Article)

2005-02-22T00:00:00Z

BACKGROUND: The clinical impact of late incomplete stent apposition (ISA) for drug-eluting stents is unknown. We sought to prospectively investigate the incidence and extent of ISA after the procedure and at 6-month follow-up of paclitaxel-eluting stents in comparison with bare metal stents (BMS) and survey the clinical significance of ISA over a period of 12 months. METHODS AND RESULTS: TAXUS II was a randomized, double-blind study with 536 patients in 2 consecutive cohorts comparing slow-release (SR; 131 patients) and moderate-release (MR; 135 patients) paclitaxel-eluting stents with BMS (270 patients). This intravascular ultrasound (IVUS) substudy included patients who underwent serial IVUS examination after the procedure and at 6 months (BMS, 240 patients; SR, 113; MR, 116). The qualitative and quantitative analyses of ISA were performed by an independent, blinded core laboratory. More than half of the instances of ISA observed after the procedure resolved at 6 months in all groups. No difference in the incidence of late-acquired ISA was observed among the 3 groups (BMS, 5.4%; SR, 8.0%; MR, 9.5%; P=0.306), with a similar ISA volume (BMS, 11.4 mm3; SR, 21.7 mm3; MR, 8.5 mm3; P=0.18). Late-acquired ISA was the result of an increase of vessel area without change in plaque behind the stent. Predictive factors of late-acquired ISA were lesion length, unstable angina, and absence of diabetes. No stent thrombosis occurred in the patients diagnosed with ISA over a period of 12 months. CONCLUSIONS: The incidence and extent of late-acquired ISA are comparable in paclitaxel-eluting stents and BMS. ISA is a pure IVUS finding without clinical repercussions.

Adjustment method for mechanical Boston scientific corporation 30 MHz intravascular ultrasound catheters connected to a Clearview console. Mechanical 30 MHz IVUS catheter adjustment. (Article)

2004-01-01T00:00:00Z

Intracoronary ultrasound (ICUS) is often used in studies evaluating new interventional techniques. It is important that quantitative measurements performed with various ICUS imaging equipment and materials are comparable. During evaluation of quantitative coronary ultrasound (QCU) software, it appeared that Boston Scientific Corporation (BSC) 30 MHz catheters connected to a Clearview ultrasound console showed smaller dimensions of an in vitro phantom model than expected. In cooperation with the manufacturer the cause of this underestimation was determined, which is described in this paper, and the QCU software was extended with an adjustment. Evaluation was performed by performing in vitro measurements on a phantom model consisting of four highly accurate steel rings (perfect reflectors) with diameters of 2, 3, 4 and 5 mm. Relative differences (unadjusted) of the phantom were respectively: 15.92, 13.01, 10.10 and 12.23%. After applying the adjustment: -0.96, -1.84, -1.35 and -1.43%. In vivo measurements were performed on 24 randomly selected ICUS studies. These showed differences for not adjusted vs. adjusted measurements of lumen-, vessel- and plaque volumes of -10.1 +/- 1.5, -6.7 +/- 0.9 and -4.4 +/- 0.6%. An off-line adjustment formula was derived and applied on previous numerical QCU output data showing relative differences for lumen- and vessel volumes of 0.36 +/- 0.51 and 0.13 +/- 0.31%. 30 MHz BSC catheters connected to a Clearview ultrasound console underestimate vessel dimensions. This can retrospectively be adjusted within QCU software as well as retrospectively on numerical QCU data using a mathematical model.

Dynamic Three-Dimensional Echocardiography Offers Advantages for Specific Site Pacing (Article)

2003-01-01T00:00:00Z

We have developed a novel technique for specific site pacing.

Clinical implications of intravascular ultrasound imaging for stenting procedures. (Article)

1999-02-15T00:00:00Z

While quantitative coronary angiography (QCA) remains the standard used to assess new interventional therapies, there is a growing interest in the use of intracoronary ultrasound (ICUS) as an additional imaging technique. During the past years, ICUS has taught us that even the most perfect angiogram after stent placement can be misleading. The study of Blessing et al1 in this issue of the Journal shows that ICUS can be reliably used for lumen measurements in stents and in reference segments. However, it also showed a high variability between observers in the degree of stent expansion, which could lead to different therapeutic strategies. Is the clinical implication of this paper that ICUS is hard to use to determine optimal stenting results? As the authors point out, many other studies are presenting results of ICUS and stenting; but are those studies comparable?

Quantitative 3·D Echocardiography of The Heart and The Coronary Vessels (Doctoral Thesis)

1998-12-16T00:00:00Z

The recognition of the existence of ultrasound is credited to L. Spallanzani (1729- 1799). In recent years, ultrasound has been used as an imaging modality in medicine. I. Edler and C.H. Hertz produced the first ultrasound images of the heart in 1953. In the 1960's great progress was made in the clinical application of ultrasound when real-time two-dimensional ultrasound scanners were developed. In 1968, J. Somer constructed the first electronic phased-array scanner and this technology is still the most widely used in ultrasound equipment. In 1974 F.E. Barber and colleagues produced a duplex scanner which integrated imaging with pulsed-wave Doppler measurements. C. Kasai and colleagues constmcted in 1982 the color-coded Doppler flow imaging system based on autocorrelation detection, providing a noninvasive "angiogram" simulation of normal and abnormal blood flow on a "beat-to-beat" basis. Transesophageal echocardiography became available to clinicians in 1985 due to the developments of 1. Soquet who invented the mono- and biplane electronic phased-array probel Echocardiography has become one of the most commonly used diagnostic imaging techniques in cardiology. The development of commercial 3-D echocardiographic equipment began in the early 1990's. In 1993 a technique allowing acquisition of tomographic parallel sliced data set of echocardiographic images of the heart with a lobster tail TEE probe, was 2 developed by the German based company "TomTec GmbH". The TEE probe had an imaging element which could be controlled by computer applying a stepping motor. They also developed an interface to the patient to record the respiration and R-R intervals. This allowed the acquisition of ultrasound images ECG-triggered and gated, which reduced motion artifacts caused by beat-to-beat and respiratory variations in cardiac dimensions and position. After the acquisition of a tomographic data set, the images were post-processed and with application of software interpolation algorithms, gaps in the data set could be filled. This post-processed data set could then be used to reconstruct 3-D volume rendered images of the heart. 3-D ultrasound provides cardiac images which more closely mimic actual anatomy'than 2-D cross-sectional linages, and may thus be easier to interpret.

ECG-Gated Three-dimensional Intravascular Ultrasound (Article)

1997-01-01T00:00:00Z

Background Automated systems for the quantitative analysis of three-dimensional (3D) sets of intravascular ultrasound (IVUS) images have been developed to reduce the time required to perform volumetric analyses; however, 3D image reconstruction by these nongated systems is frequently hampered by cyclic artifacts. Methods and Results We used an ECG-gated 3D IVUS image acquisition workstation and a dedicated pullback device in atherosclerotic coronary segments of 30 patients to evaluate (1) the feasibility of this approach of image acquisition, (2) the reproducibility of an automated contour detection algorithm in measuring lumen, external elastic membrane, and plaque+media cross-sectional areas (CSAs) and volumes and the cross-sectional and volumetric plaque+media burden, and (3) the agreement between the automated area measurements and the results of manual tracing. The gated image acquisition took 3.9±1.5 minutes. The length of the segments analyzed was 9.6 to 40.0 mm, with 2.3±1.5 side branches per segment. The minimum lumen CSA measured 6.4±1.7 mm2, and the maximum and average CSA plaque+media burden measured 60.5±10.2% and 46.5±9.9%, respectively. The automated contour-detection required 34.3±7.3 minutes per segment. The differences between these measurements and manual tracing did not exceed 1.6% (SD<6.8%). Intraobserver and interobserver differences in area measurements (n=3421; r=.97 to.99) were <1.6% (SD<7.2%); intraobserver and interobserver differences in volumetric measurements (n=30; r=.99) were <0.4% (SD<3.2%). Conclusions ECG-gated acquisition of 3D IVUS image sets is feasible and permits the application of automated contour detection to provide reproducible measurements of the lumen and atherosclerotic plaque CSA and volume in a relatively short analysis time.

Simpson's rule for the volumetric ultrasound assessment of atherosclerotic coronary arteries: a study with ECG-gated three-dimensional intravascular ultrasound. (Article)

1997-01-01T00:00:00Z

BACKGROUND: Volumetric intravascular ultrasound (IVUS) assessment provides complementary information on atherosclerotic plaques. The volumes can be calculated by applying Simpson's rule to cross-sectional area data of multiple IVUS images, acquired with a fixed sample spacing, which is the distance (along the vessel's axis) between two images. OBJECTIVE: To evaluate the effect of different sample spacings on the results of volumetric IVUS measurements. METHODS: A stepwise electrocardiographically gated IVUS image-acquisition and automated three-dimensional analysis approach was applied to 26 patients. Twenty-eight coronary segments with mild-to-moderate coronary atherosclerosis were examined. Volumetric measurements of five images per mm (i.e. sample spacing 0.2 mm), representing a complete scanning of the coronary segment, were considered the optimal standard, against which volumetric measurements of three, one, and one-half images per mm (i.e. larger sample spacings) were compared. RESULTS: The lumen, total vessel, and plaque volumes obtained with five images per mm were 183.3 +/- 2.8, 350.6 +/- 141.6, and 167.3 +/- 89.2 mm3. There was an excellent correlation (r = 0.99, P < 0.001) between these data and volumetric measurements with larger sample spacings. The volumetric measurements with larger sample spacings differed on average only by a little (< 0.7%) from the optimal standard measurements. However, a relatively small, but significant, increase in SD of these differences was associated with the wider sample spacings (< 3.6%, P < 0.05). CONCLUSIONS: The width of the sample spacing has a relatively small but significant impact on the variability of volumetric intravascular ultrasound measurements. This should be considered when designing future volumetric studies. The electrocardiographically gated acquisition of five IVUS images per mm axial length during a stepwise transducer pull-back is an ideal approach, particularly when addressing with IVUS volumetric changes that are assumed small, such as those expected in studies of the progression and regression of atherosclerosis.

Three dimensional reconstruction of cross sectional intracoronary ultrasound: clinical or research tool? (Article)

1995-01-01T00:00:00Z