Abstract:Atherosclerosis is the leading cause of cardiovascular mortality and morbidity in the developed world. Intravascular ultrasound (IVUS) is a widely used imaging modality providing complementary diagnostic information to angiography regarding the vessel wall of the coronary arteries. IVUS has been used for assessment of ambiguous angiographic lesions, evaluation of new interventional devices and in atherosclerosis progression-regression trials. However, the standard gray-scale IVUS has limited value for the accu… Show more
“…Although there is a tendency to increase the transducer frequency with a net result on increasing image resolution, current probes use variable frequencies, mostly between 20 and 40 MHz (center frequencies) and axial/lateral resolutions 60–200 μm/110–400 μm, respectively [ 113 ]. We highlight the importance of virtual histology (VH) IVUS, which is able to provide a classification of plaques through mathematically constructed tissue maps—fibrous, fibrofatty, necrotic core, calcific [ 114 ]. Grayscale and VH-IVUS techniques will be comprehensively reviewed within this chapter through a coronary atherosclerosis-dependent perspective.…”
Section: Invasive Us Methods: Where Are We?mentioning
confidence: 99%
“…The implementation of IVUS-based post-processing methods utilizing radiofrequency data analysis and elastography overcame the constraints of qualitative visual interpretation of conventional grayscale IVUS [ 115 , 117 , 118 ]. Virtual histology IVUS (VH-IVUS) utilizes US backscattered signal to provide an accurate portrayal of plaque morphology into four major types, as shown in Table 3 [ 114 , 118 , 120 ]. The gross anatomy and VH-IVUS schematic representation of several atherosclerotic plaques are represented in Figure 4 .…”
Section: Invasive Us Methods: Where Are We?mentioning
Atherosclerosis is a key pathological process that causes a plethora of pathologies, including coronary artery disease, peripheral artery disease, and ischemic stroke. The silent progression of the atherosclerotic disease prompts for new surveillance tools that can visualize, characterize, and provide a risk evaluation of the atherosclerotic plaque. Conventional ultrasound methods—bright (B)-mode US plus Doppler mode—provide a rapid, cost-efficient way to visualize an established plaque and give a rapid risk stratification of the patient through the Gray–Weale standardization—echolucent plaques with ≥ 50% stenosis have a significantly greater risk of ipsilateral stroke. Although rather disputed, the measurement of carotid intima-media thickness (C-IMT) may prove useful in identifying subclinical atherosclerosis. In addition, contrast-enhanced ultrasonography (CEUS) allows for a better image resolution and the visualization and quantification of plaque neovascularization, which has been correlated with future cardiovascular events. Newly emerging elastography techniques such as strain elastography and shear-wave elastography add a new dimension to this evaluation—the biomechanics of the arterial wall, which is altered in atherosclerosis. The invasive counterpart, intravascular ultrasound (IVUS), enables an individualized assessment of the anti-atherosclerotic therapies, as well as a direct risk assessment of these lesions through virtual histology IVUS.
“…Although there is a tendency to increase the transducer frequency with a net result on increasing image resolution, current probes use variable frequencies, mostly between 20 and 40 MHz (center frequencies) and axial/lateral resolutions 60–200 μm/110–400 μm, respectively [ 113 ]. We highlight the importance of virtual histology (VH) IVUS, which is able to provide a classification of plaques through mathematically constructed tissue maps—fibrous, fibrofatty, necrotic core, calcific [ 114 ]. Grayscale and VH-IVUS techniques will be comprehensively reviewed within this chapter through a coronary atherosclerosis-dependent perspective.…”
Section: Invasive Us Methods: Where Are We?mentioning
confidence: 99%
“…The implementation of IVUS-based post-processing methods utilizing radiofrequency data analysis and elastography overcame the constraints of qualitative visual interpretation of conventional grayscale IVUS [ 115 , 117 , 118 ]. Virtual histology IVUS (VH-IVUS) utilizes US backscattered signal to provide an accurate portrayal of plaque morphology into four major types, as shown in Table 3 [ 114 , 118 , 120 ]. The gross anatomy and VH-IVUS schematic representation of several atherosclerotic plaques are represented in Figure 4 .…”
Section: Invasive Us Methods: Where Are We?mentioning
Atherosclerosis is a key pathological process that causes a plethora of pathologies, including coronary artery disease, peripheral artery disease, and ischemic stroke. The silent progression of the atherosclerotic disease prompts for new surveillance tools that can visualize, characterize, and provide a risk evaluation of the atherosclerotic plaque. Conventional ultrasound methods—bright (B)-mode US plus Doppler mode—provide a rapid, cost-efficient way to visualize an established plaque and give a rapid risk stratification of the patient through the Gray–Weale standardization—echolucent plaques with ≥ 50% stenosis have a significantly greater risk of ipsilateral stroke. Although rather disputed, the measurement of carotid intima-media thickness (C-IMT) may prove useful in identifying subclinical atherosclerosis. In addition, contrast-enhanced ultrasonography (CEUS) allows for a better image resolution and the visualization and quantification of plaque neovascularization, which has been correlated with future cardiovascular events. Newly emerging elastography techniques such as strain elastography and shear-wave elastography add a new dimension to this evaluation—the biomechanics of the arterial wall, which is altered in atherosclerosis. The invasive counterpart, intravascular ultrasound (IVUS), enables an individualized assessment of the anti-atherosclerotic therapies, as well as a direct risk assessment of these lesions through virtual histology IVUS.
“…Intensity is the gray-scale value of each pixel obtained by the amplitude of the reflected ultrasound RF signal from plaque components [38]. As reported in [30], the plaque components typically have a different intensity distribution whereby NC and DC shows higher echo-intensities than FT and FFT (Fig.…”
BackgroundIVUS is widely used to quantitatively assess coronary artery disease. The purpose of this study was to automatically characterize dense calcium (DC) tissue in the gray scale intravascular ultrasound (IVUS) images using the image textural features.MethodsA total of 316 Gy-scale IVUS and corresponding virtual histology images from 26 patients with acute coronary syndrome who underwent IVUS along with X-ray angiography between October 2009 to September 2014 were retrospectively acquired and analyzed. One expert performed all procedures and assessed their IVUS scans. After image acquisition, the DC candidate and corresponding acoustic shadow regions were automatically determined. Then, nine image-base feature groups were extracted from the DC candidates. In order to reduce the dimensionalities, principal component analysis (PCA) was performed, and selected feature sets were utilized as an input for a deep belief network. Classification results were validated using 10-fold cross validation.ResultsThe dimensionality of the feature map was efficiently reduced by 50% (from 66 to 33) without any performance decrease using PCA method. Sensitivity, specificity, and accuracy of the proposed method were 92.8 ± 0.1%, 85.1 ± 0.1%, and 88.4 ± 0.1%, respectively (p < 0.05). We found that the window size could largely influence the characterization results, and selected the 5 × 5 size as the best condition. We also validated the performance superiority of the proposed method with traditional classification methods.ConclusionsThese experimental results suggest that the proposed method has significant clinical applicability for IVUS-based cardiovascular diagnosis.
“…The modality of the transducer being intravascular allows better characterization of vessels because of lack of interference from the soft tissues covering it. This modality, combined with different types of analysis software programs, produces qualitative and quantitative information about vessel integrity and lumen size [5].Figure 2Pre-revision venogram demonstrating obstruction of contrast flow.…”
Intrapelvic acetabular screw placement is a known complication of total hip arthroplasty and is associated with risks including damage to neurovascular and intrapelvic structures such as the external iliac vessels, obturator vessels, and iliopsoas muscles. Retrieval of intrapelvic acetabular screws is similarly fraught with risk, and appropriate imaging should be performed preoperatively. We report on a case of intrapelvic acetabular screw placement with abutment of the external iliac vein, which was managed with intraoperative venogram and intravenous ultrasound to maintain access to the external iliac vein and successfully show no vascular tear before and after screw removal.
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