Correlation between high frequency intravascular ultrasound and histomorphology in human coronary arteries

Prati, Francesco; Arbustini, Eloisa; Labellarte, Antonella; Bello, Barbara Dal; Sommariva, Luigi; Mallus, Maria Teresa; Pagano, Andrew; Boccanelli, Alessandro

doi:10.1136/heart.85.5.567

Cited by 108 publications

(71 citation statements)

References 17 publications

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“…Furthermore, calcified and noncalcified plaque components can be identified. However, the sensitivity to identify fatty plaque components remains low [8,9]. Recent rf-(radiofrequency) based tissue identification strategies appear to have better performance [9,10].…”

Section: Intravascular Palpography Is a Technique Based On Intravascumentioning

confidence: 99%

“…However, the distribution of the strain in the three-dimensional (3-D) geometry of an artery is an important tool to identify the presence of high-strain spots, their amount and distribution. Especially, since the correlation between plaque vulnerability and parameters provided by the echogram is low [8,9] selection of cross-sections based on the IVUS echogram introduces selection bias and increases the chance to miss the vulnerable spot. Additionally, during longitudinal monitoring of patients it is extremely difficult to refind the same spot after some months.…”

Section: Three-dimensional Palpographymentioning

confidence: 99%

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Intravascular Palpography for High-Risk Vulnerable Plaque Assessment

Schaar

Korte

Mastik³

et al. 2003

Herz

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Background:The composition of an atherosclerotic plaque is considered more important than the degree of stenosis. An unstable lesion may rupture and cause an acute thrombotic reaction. Most of these lesions contain a large lipid pool covered by an inflamed thin fibrous cap. The stress in the cap increases with decreasing cap thickness and increasing macrophage infiltration. Intravascular ultrasound (IVUS) palpography might be an ideal technique to assess the mechanical properties of high-risk plaques. Technique: Palpography assesses the local mechanical properties of tissue using its deformation caused by the intraluminal pressure. In Vitro Validation:The technique was validated in vitro using diseased human coronary and femoral arteries. Especially between fibrous and fatty tissue, a highly significant difference in strain (p = 0.0012) was found. Additionally, the predictive value to identify the vulnerable plaque was investigated. A high-strain region at the lumen-vessel wall boundary has an Intravaskuläre Palpographie zur Erfassung vulnerabler Hochrisikoplaques

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Section: Intravascular Palpography Is a Technique Based On Intravascumentioning

confidence: 99%

Section: Three-dimensional Palpographymentioning

confidence: 99%

Intravascular Palpography for High-Risk Vulnerable Plaque Assessment

Schaar

Korte

Mastik³

et al. 2003

Herz

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“…However, the sensitivity and specificity to detect lipid cores remains low. 3,4 IVUS elastography assesses the local radial strain in the tissue caused by an intraluminal pressure differential. In vitro experiments revealed different strain values in fibrous and fatty plaques in human coronary and femoral arteries.…”

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confidence: 99%

Identification of Atherosclerotic Plaque Components With Intravascular Ultrasound Elastography In Vivo

et al. 2002

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Background-Intravascular ultrasound elastography assesses the local strain of the atherosclerotic vessel wall. In the present study, the potential to identify different plaque components in vivo was investigated. Methods and Results-Atherosclerotic external iliac and femoral arteries (nϭ24) of 6 Yucatan pigs were investigated.Before termination, elastographic data were acquired with a 20-MHz Visions catheter. Two frames acquired at end-diastole with a pressure differential of Ϸ4 mm Hg were acquired to obtain the elastograms. Before dissection, x-ray was used to identify the arterial segments that had been investigated by ultrasound. Specimens were stained for collagen, fat, and macrophages. Plaques were classified as absent, early fibrous lesion, early fatty lesion, or advanced fibrous plaque. The average strains in the plaque-free arterial wall (0.21%) and the early (0.24%) and advanced fibrous plaques (0.22%) were similar. Higher average strain values were observed in fatty lesions (0.46%) compared with fibrous plaques (Pϭ0.007). After correction for confounding by lipid content, no additional differences in average strain were found between plaques with and without macrophages (Pϭ0.966). Receiver operating characteristic analysis revealed a sensitivity and a specificity of 100% and 80%, respectively, to identify fatty plaques. The presence of a high-strain spot (strain Ͼ1%) has 92% sensitivity and 92% specificity to identify macrophages. Conclusions-To the best of our knowledge, this is the first time that intravascular ultrasound elastography has been validated in vivo. Intravascular ultrasound (IVUS) has proven to be a powerful technique to assess the geometry of the vessel wall and plaque. However, the sensitivity and specificity to detect lipid cores remains low. 3,4 IVUS elastography assesses the local radial strain in the tissue caused by an intraluminal pressure differential. In vitro experiments revealed different strain values in fibrous and fatty plaques in human coronary and femoral arteries. 5 Feasibility experiments in patients showed that reproducible elastograms could be obtained. 6 The aim of this study was to validate IVUS elastography in vivo with an atherosclerotic Yucatan minipig model. Additionally, we studied whether atheroma and macrophages were related with strain values. Methods AnimalsSix atherosclerotic Yucatan pigs, average weight 40 kg, were studied. To induce atherosclerosis, pigs were put on an atherogenic diet. Two weeks thereafter, the external iliac and femoral arteries were denuded with a 4-F endothelial Fogarty catheter. The atherogenic diet was continued for 9 to 10 months after which femoral and internal iliac arteries were stented for the purpose of another study. Subsequently, the atherogenic diet was replaced by a regular diet. No intervention was performed in the denuded external iliac arteries that were visualized for the present study. The following 42 days, 3 pigs were treated with a drug and 3 pigs served as controls for the purpose of another study. ANOVA reveale...

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“…Fibrous plaque can now be characterized as tissue that has a density that is similar or higher than that of the adventitia and hence will appear in grey levels that are mainly higher than that of the mean grey value of the adventitia [5][6][7]. Analogous, softer material has a lower grey value.…”

Section: Characterization Using Echogenicitymentioning

confidence: 99%

“…Studies that compared histology to intravascular ultrasound learned that different structures correspond to different video-densities in the images; structures that appear white indicating high echogenicity, mainly consist of dense fibrous or calcific tissue. The darker, echolucent or hypoechogenic areas contain larger amounts of loose fibrous or smooth, muscle-rich tissue and thrombotic or necrotic elements [5]. Based on this idea, video-densitometry can be used for plaque characterization [7].…”

Section: Introductionmentioning

confidence: 99%

Computer assisted three-dimensional plaque characterization in intracoronary ultrasound studies

Winter

Heller

Hamers

et al. 2003

Computers in Cardiology, 2003

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IntroductionIntracoronary ultrasound (ICUS) is used as a tomographic imaging technique to visualize the vessel wall morphology and to identify atherosclerotic plaque [1]. To examine a selected coronary vessel segment an ICUS imaging catheter is pulled back through the coronary artery, meanwhile acquiring a series of cross sectional images. Three-dimensional (3D) reconstruction of the segment and contour tracing in the ICUS images facilitate subsequent quantitative coronary ultrasound (QCU) analysis and qualifies ICUS to be used in clinical trials to evaluate the results of novel catheter-based interventional techniques as well as pharmaceutical treatments [2].Knowledge of plaque composition is a valuable clinical parameter to assess information on plaque formation, progression and rupture [3] and plays an important role in gaining insight in the processes underlying events of sudden cardiac death [4]. Studies that compared histology to intravascular ultrasound learned that different structures correspond to different video-densities in the images; structures that appear white indicating high echogenicity, mainly consist of dense fibrous or calcific tissue. The darker, echolucent or hypoechogenic areas contain larger amounts of loose fibrous or smooth, muscle-rich tissue and thrombotic or necrotic elements [5]. Based on this idea, video-densitometry can be used for plaque characterization [7].Manual classification of tissue in the ICUS images for an entire 3D segment is very time-consuming, and potentially error prone. The analyst has to judge the high number of ICUS images (typically 1500 images per minute pullback acquired at a speed of 0.5 mm/s) in a consistent way, which may result in large inter-and intraobserver variability. Moreover, the human eye can discriminate only about 32 levels of grey, while the ultrasound images can contain 256 levels. Computerassisted grey level interpretation (labelling) and measurement in an entire 3D segment can overcome these problems. Therefore we developed a method, based on video-densitometry, that can automatically label plaque tissue and quantify each labelled type in an existing ICUS pullback. This paper describes this method and shows how the results are presented and visualized in the new research tool. MethodsICUS pullbacks can be stored either on S-VHS videotape, or digitally on CD-ROM. Images originating from standard PAL S-VHS tapes are first de-interlaced to remove the effect of having duplicate images in one image frame. A Gaussian low-pass filter is applied to each cross section to smooth the effect of natural intensity fluctuations caused by the texture of that specific tissue. This ensures that echogenicity measurements focus on the identification of regions instead of individual pixels.ICUS studies that are not acquired ECG-gated [8], are retrospectively image-based gated with the IntelliGate ® [13,14] method before QCU analysis. This allows accurate QCU results in anatomically correctly displayed segments. ECG -gating synchronizes the acquisition o...

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Correlation between high frequency intravascular ultrasound and histomorphology in human coronary arteries

Cited by 108 publications

References 17 publications

Intravascular Palpography for High-Risk Vulnerable Plaque Assessment

Intravascular Palpography for High-Risk Vulnerable Plaque Assessment

Identification of Atherosclerotic Plaque Components With Intravascular Ultrasound Elastography In Vivo

Computer assisted three-dimensional plaque characterization in intracoronary ultrasound studies

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