Resolution Limitations in Intravascular Ultrasound Imaging

Benkeser, P.J.; Churchwell, André L.; Lee, Chankil; Abouelnasr, Dana

doi:10.1016/s0894-7317(14)80486-0

Cited by 39 publications

(11 citation statements)

References 17 publications

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“…The BlandAltman analysis showed that the bias of the color IVUS measurement of the thickness of fibrous cap was 0.00Ϯ0.10 mm compared with the histological measurement. Considering the resolution of IVUS, which was Ϸ0.05 mm, 24 this SD of 0.10 mm was quite acceptable. It has been documented that plaque is prone to rupture when the thickness of fibrous cap becomes Ͻ0.2 mm.…”

Section: Accuracy Of the Present Color Mapping Techniquementioning

confidence: 86%

Detection of Fibrous Cap in Atherosclerotic Plaque by Intravascular Ultrasound by Use of Color Mapping of Angle-Dependent Echo-Intensity Variation

et al. 2001

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Background-The thickness of the fibrous cap is a major determinant in the vulnerability of atherosclerotic plaque to rupture. It has been demonstrated that intravascular ultrasound (IVUS) backscatter from fibrous tissue is strongly dependent on the ultrasound beam angle of incidence. This study investigated the feasibility of using a new IVUS color mapping technique representing the angle-dependent echo-intensity variation to determine the thickness of the fibrous cap in atherosclerotic plaque. Methods and Results-Nineteen formalin-fixed noncalcified human atherosclerotic plaques from necropsy were imaged in vitro with a 30-MHz IVUS catheter. The IVUS catheter was moved coaxially relative to the plaque. The images showing maximum and minimum echo intensity of the plaque surface were selected to calculate the angle-dependent echo-intensity variation. A colorized representation of the echo-intensity variation in the plaque was obtained from the 2 IVUS images. A clearly bordered area with large variation in echo intensity was revealed for each plaque surface in the colorized IVUS image. The thickness (x, mm) of this area correlated significantly with that of fibrous cap (y, mm) measured from histologically prepared sections as yϭ1.05xϪ0. 01 (rϭ0.81, PϽ0.0001). Bland-Altman analysis also supported the reliability of this method (mean difference, 0.00Ϯ0.10 mm). Conclusions-This novel technique for color mapping the echo-intensity variation in IVUS provided an accurate representation of the thickness of the fibrous cap in atherosclerotic plaque. This method may be useful in assessing plaque vulnerability to rupture in atherosclerosis.

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Section: Accuracy Of the Present Color Mapping Techniquementioning

confidence: 86%

Detection of Fibrous Cap in Atherosclerotic Plaque by Intravascular Ultrasound by Use of Color Mapping of Angle-Dependent Echo-Intensity Variation

et al. 2001

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“…IVUS can accurately detect the presence of CS deposits Ͼ0.25 mm but lacks the ability to detect the presence of lipid pools. 5,7 Not only can Raman spectroscopy identify the major chemical components of the coronary arterial wall, such as total cholesterol, CS, triglyceridesϩphospholipids, and ␤-carotene, but it can also quantify these amounts. 17,24,26 The detection and quantification of cholesterol may be important in clinical practice, in view of the fact that a number of recent studies have demonstrated that plaque rupture occurs primarily in lipid-rich plaques covered with a fragile fibrous cap.…”

Section: Discussionmentioning

confidence: 99%

“…5 Also, the sensitivity of IVUS in detecting lipid pools is low (46%). [5][6][7] Recent studies have suggested that plaque composition and morphology, rather than size or volume, are indicators of plaque rupture, which may lead to an acceleration of clinical symptoms. 8 -10 Specifically, the accumulation of cholesterol in the arterial intima has been shown to play an important role in the progression and regression of atherosclerotic plaques.…”

mentioning

confidence: 99%

Intravascular Ultrasound Combined With Raman Spectroscopy to Localize and Quantify Cholesterol and Calcium Salts in Atherosclerotic Coronary Arteries

Römer

Brennan

Puppels

et al. 2000

ATVB

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Abstract-Coronary intravascular ultrasound (IVUS) can assess arterial wall architecture and localize large intravascular deposits, but it does not provide quantitative chemical information, which is essential in the evaluation of atherosclerotic lesions. Previously, it has been shown that Raman spectroscopy can be used to accurately quantify the relative weights of cholesterol, calcium salts, triglycerides, and phospholipids in homogenized arterial tissue. In the present study, we explore some benefits of combining IVUS and Raman spectroscopy to evaluate the intact arterial wall. IVUS images were collected in vitro from human coronary arterial segments in various stages of disease (nϭ7). The images were divided into radial segments (11 to 28 per image, 332 in total), each of which was classified visually as calcified or noncalcified tissue. The arteries were opened longitudinally, and Raman spectra were collected from locations at 0.5-mm intervals across the arterial luminal circumference. The spectra were used to calculate the chemical composition of the arterial wall at the examined locations. Generally, locations containing large amounts of calcium salts, as determined with Raman spectroscopy, were classified as calcified with IVUS. However, small calcific deposits (Ͻ6% of weight) were not readily detected with IVUS. The amounts and location of cholesterol determined with Raman spectroscopy were correlated closely with the presence of cholesterol observed by histochemistry, but these deposits could not be located accurately by IVUS. [1][2][3][4] Although IVUS adds valuable information to that obtained by coronary angiography about the degree of luminal narrowing, it cannot detect calcific deposits measuring Ͻ0.25 mm in diameter, which are visible by histological examination under high-power magnification. 5 Also, the sensitivity of IVUS in detecting lipid pools is low (46%). [5][6][7] Recent studies have suggested that plaque composition and morphology, rather than size or volume, are indicators of plaque rupture, which may lead to an acceleration of clinical symptoms. 8 -10 Specifically, the accumulation of cholesterol in the arterial intima has been shown to play an important role in the progression and regression of atherosclerotic plaques. 8 Raman spectroscopy is a promising technique that can be used to characterize the chemical composition of biological tissue. A Raman spectrum of a given molecule is unique, 11-14 which makes Raman spectroscopy ideal for detecting, identifying, and diagnosing diseases that involve gross chemical changes in tissue, such as atherosclerosis. Raman spectra can be obtained by processing the collected light that is scattered from an artery as it is illuminated with a laser beam. With sensitive laboratory equipment, quality spectra can be collected in less than a second, and most spectral features are visible in spectra collected in only a few seconds via optical fiber catheters. 15 Because Raman spectroscopy is nondestructive, one can collect spectra of the tissue in situ, ...

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“…The pulsed ultrasound was performed with an average power of 17.8 mW, beam diameter of 0.24 cm, and a focal length of 2.1 cm. The ultrasound beam is being used over 1.5 cm proximal to the focus, resulting in an essentially collimated beam (12). The pulse repetition rate was 1.3 ms, with an average pulse intensity of 225 W͞cm 2 .…”

Section: Methodsmentioning

confidence: 99%

Ultrasound induced improvement in optical coherence tomography (OCT) resolution

Schenk

Brezinski

2002

Proc. Natl. Acad. Sci. U.S.A.

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Optical coherence tomography (OCT) is a rapidly emerging technology for high-resolution biomedical imaging. The axial resolution of this technology is determined by the bandwidth of the source. Commercial sources generally provide resolutions of 10 -20 m whereas laboratory-based solid state lasers have resolutions of Ϸ4 m. The resolution in tissue depends almost exclusively on detecting single scattered events. However, the phenomenon known as multiple scattering results in a deterioration of resolution as a function of depth. In this study, OCT was combined with ultrasound in an attempt to reduce the effect of multiple scattering. The theory is that, with parallel ultrasound and OCT beams, multiply scattered light with a momentum component significantly perpendicular to the OCT beam will be reduced because the light is Doppler shifted outside the bandpass filter of the OCT detection electronics. A 7.5-MHz ultrasound transducer was used to introduce the photon͞phonon interaction. A reflecting metal plate was placed within biological tissue, and the point spread function (PSF) was assessed off the reflector. The PSF was determined in the presence of no ultrasound, pulsed ultrasound, and continuouswave (CW) ultrasound. CW ultrasound resulted in a 17% improvement (P < 0.001) in resolution and pulsed ultrasound resulted in 8% (P < 0.01). Image noise reduction could also be noted. Combining OCT with a parallel ultrasound beam results in an improvement in resolution through a reduced effect of multiple scattering due to photon͞phonon interaction. With higher frequencies, better control of the acoustical beam, and tests in media with higher rates of multiple scattering, improved results are anticipated.multiple scattering ͉ osteoarthritis ͉ surveillance ͉ plaque rupture ͉ imaging

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Resolution Limitations in Intravascular Ultrasound Imaging

Cited by 39 publications

References 17 publications

Detection of Fibrous Cap in Atherosclerotic Plaque by Intravascular Ultrasound by Use of Color Mapping of Angle-Dependent Echo-Intensity Variation

Detection of Fibrous Cap in Atherosclerotic Plaque by Intravascular Ultrasound by Use of Color Mapping of Angle-Dependent Echo-Intensity Variation

Intravascular Ultrasound Combined With Raman Spectroscopy to Localize and Quantify Cholesterol and Calcium Salts in Atherosclerotic Coronary Arteries

Ultrasound induced improvement in optical coherence tomography (OCT) resolution

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