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Ottakath N, Al-Maadeed S, Zughaier SM, Elharrouss O, Mohammed HH, Chowdhury MEH, Bouridane A. Ultrasound-Based Image Analysis for Predicting Carotid Artery Stenosis Risk: A Comprehensive Review of the Problem, Techniques, Datasets, and Future Directions. Diagnostics (Basel) 2023; 13:2614. [PMID: 37568976 PMCID: PMC10417708 DOI: 10.3390/diagnostics13152614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/25/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
The carotid artery is a major blood vessel that supplies blood to the brain. Plaque buildup in the arteries can lead to cardiovascular diseases such as atherosclerosis, stroke, ruptured arteries, and even death. Both invasive and non-invasive methods are used to detect plaque buildup in the arteries, with ultrasound imaging being the first line of diagnosis. This paper presents a comprehensive review of the existing literature on ultrasound image analysis methods for detecting and characterizing plaque buildup in the carotid artery. The review includes an in-depth analysis of datasets; image segmentation techniques for the carotid artery plaque area, lumen area, and intima-media thickness (IMT); and plaque measurement, characterization, classification, and stenosis grading using deep learning and machine learning. Additionally, the paper provides an overview of the performance of these methods, including challenges in analysis, and future directions for research.
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Affiliation(s)
- Najmath Ottakath
- Department of Computer Science and Engineering, Qatar University, Doha 2713, Qatar; (S.A.-M.); (O.E.); (H.H.M.)
| | - Somaya Al-Maadeed
- Department of Computer Science and Engineering, Qatar University, Doha 2713, Qatar; (S.A.-M.); (O.E.); (H.H.M.)
| | | | - Omar Elharrouss
- Department of Computer Science and Engineering, Qatar University, Doha 2713, Qatar; (S.A.-M.); (O.E.); (H.H.M.)
| | - Hanadi Hassen Mohammed
- Department of Computer Science and Engineering, Qatar University, Doha 2713, Qatar; (S.A.-M.); (O.E.); (H.H.M.)
| | | | - Ahmed Bouridane
- Centre for Data Analytics and Cybersecurity, University of Sharjah, Sharjah 27272, United Arab Emirates;
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2
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Lai TY, Averkiou MA. Contrast-Enhanced Ultrasound with Optimized Aperture Patterns and Bubble Segmentation Based on Echo Phase. ULTRASOUND IN MEDICINE & BIOLOGY 2023; 49:186-202. [PMID: 36441029 PMCID: PMC9713587 DOI: 10.1016/j.ultrasmedbio.2022.08.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 08/23/2022] [Accepted: 08/24/2022] [Indexed: 06/16/2023]
Abstract
Amplitude modulation (AM) suppresses tissue signals and detects microbubble signals in contrast-enhanced ultrasound (CEUS) and is often implemented with checkerboard apertures. However, possible crosstalk between transmitting and non-transmitting array elements may compromise tissue suppression in AM. Using AM aperture patterns other than the conventional checkerboard approach (one on, one off) may reduce the degree of crosstalk and increase the contrast-to-tissue-ratio (CTR) compared with conventional AM. Furthermore, previous studies have reported that the phase difference between the echoes in AM pulsing sequences may be used to segment tissue and microbubbles and improve tissue signal suppression and the CTR of CEUS images. However, the CTR of the image produced by alternative AM aperture patterns and the effect of segmentation approach on these alternative apertures have not been investigated. We evaluated a number of AM aperture patterns to find an optimal AM aperture pattern that provides the highest CTR. We found that the aperture that uses alternating groups of two elements, AM2, had the highest CTR for the probe evaluated. In addition, a segmentation technique based on echo phase differences (between the full and half-pulses, ΔΦAM, between the complementary half-pulses, ΔΦhalf, and the maximum of the two ΔΦmax) was also considered in the AM aperture optimization process. The segmentation approach increases the CTR by about 25 dB for all apertures. Finally, AM2 segmented with ΔΦmax had a 7-dB higher CTR in a flow phantom and a 6-dB higher contrast in a perfused pig liver than conventional AM segmented with ΔΦAM, and it is the optimal transmit aperture design.
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Affiliation(s)
- Ting-Yu Lai
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
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3
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Sultan SR, Bashmail FT, Alzahrani NA, Alharbi SI, Anbar R, Alkharaiji M. Contrast-enhanced ultrasound for the evaluation of symptomatic and asymptomatic carotid plaques: A systematic review and meta-analysis. Echocardiography 2022; 39:1032-1043. [PMID: 35768892 DOI: 10.1111/echo.15407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/22/2022] [Accepted: 06/09/2022] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Contrast-enhanced ultrasound (CEUS) is a promising imaging modality for the assessment of plaque vulnerability. We aimed to systematically review and meta-analyze the ability of CEUS parameters to differentiate between symptomatic and asymptomatic carotid plaques and to assess its reproducibility. METHODS PubMed, EMBASE, and Cochrane Library databases were searched for studies that potentially evaluated carotid plaques using CEUS. From the initial 2870 searches, 11 relevant publications comprising a total of 821 carotid plaques were reviewed. Data on CEUS parameters including quantitative and semi-quantitative parameters were extracted and analyzed. RESULTS The overall analysis showed significantly higher CEUS parameters in symptomatic carotid plaques compared to asymptomatic carotid plaques (standardised mean difference (SMD) .95, 95% confidence interval (CI) .56-1.27, p < .01). Intra and inter-observer reproducibility of quantitative CEUS parameters were excellent (intra-observer, r = .95, 95% CI .87-1; inter-observer, r = .93, 95% CI .80-.1). Semi-quantitative CEUS parameters showed good intra-observer reliability and moderate inter-observer reliability (intra-observer, r = .77, 95% CI .64-.89; inter-observer, r = .75, 95% CI .61-.89). Heterogeneity among studies compared CEUS parameters in symptomatic and asymptomatic plaques and studies assessed inter-observer reproducibility, and significant biases in studies assessing CEUS reproducibility were present. CONCLUSION CEUS is a useful vascular imaging method to differentiate between symptomatic and asymptomatic carotid plaques with moderate to excellent reproducibility. Quantitative CEUS analysis appeared to be more sensitive and reliable in assessing carotid plaques than semi-quantitative parameters. Further longitudinal prospective trials evaluating carotid plaque in asymptomatic population using CEUS to determine plaque characteristics that can become symptomatic are required.
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Affiliation(s)
- Salahaden R Sultan
- Department of Radiologic Sciences, College of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Fatima T Bashmail
- Department of Radiologic Sciences, College of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Nouf A Alzahrani
- Department of Radiologic Sciences, College of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Shahd I Alharbi
- Department of Radiologic Sciences, College of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Rayan Anbar
- Department of Radiologic Sciences, College of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mohammed Alkharaiji
- Department of Public Health, College of Health Sciences, Saudi Electronic University, Riyadh, Saudi Arabia
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4
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Aarli SJ, Thomassen L, Waje-Andreassen U, Logallo N, Kvistad CE, Næss H, Fromm A. The Course of Carotid Plaque Vulnerability Assessed by Advanced Neurosonology. Front Neurol 2021; 12:702657. [PMID: 34489850 PMCID: PMC8417551 DOI: 10.3389/fneur.2021.702657] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 07/28/2021] [Indexed: 11/17/2022] Open
Abstract
Background: Carotid artery atherosclerosis is a major risk factor for ischemic stroke. This risk is related to plaque vulnerability and is characterized by plaque morphology, intraplaque neovascularization, and cerebral microembolization. Advanced neurosonology can identify vulnerable plaques and aid in preventing subsequent stroke. We aimed to assess the time course of cerebral microembolization and intraplaque neovascularization during 6 months of follow-up and to explore the utility of advanced neurosonology in patients with acute cerebral ischemia. Methods: Fifteen patients with acute cerebral ischemia and carotid artery plaques underwent comprehensive extra- and intracranial ultrasound examinations, including microemboli detection and contrast-enhanced ultrasound. The examinations were repeated after 3 and 6 months. Results: We examined 28 plaques in 15 patients. The ultrasonographic features of plaque vulnerability were frequent in symptomatic and asymptomatic plaques. There were no significant differences in stenosis degree, plaque composition, plaque surface, neovascularization, or cerebral microembolization between symptomatic and asymptomatic plaques, but symptomatic plaques had a higher number of vulnerable features. None of the patients had recurrent clinical stroke or transient ischemic attack during the follow-up period. We observed a decrease in cerebral microembolization at 6 months, but no significant change in intraplaque neovascularization. Conclusions: In patients with acute cerebral ischemia and carotid artery plaques, cerebral microembolization decreased during 6 months of follow-up, indicating plaque stabilization. Clinical Trial Registration:ClinicalTrial.gov, identifier NCT02759653.
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Affiliation(s)
- Sander Johan Aarli
- Department of Neurology, Haukeland University Hospital, Bergen, Norway.,Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Lars Thomassen
- Department of Neurology, Haukeland University Hospital, Bergen, Norway.,Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Ulrike Waje-Andreassen
- Department of Neurology, Haukeland University Hospital, Bergen, Norway.,Department of Biological and Medical Psychology, University of Bergen, Bergen, Norway
| | - Nicola Logallo
- Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway
| | - Christopher Elnan Kvistad
- Department of Neurology, Haukeland University Hospital, Bergen, Norway.,Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Halvor Næss
- Department of Neurology, Haukeland University Hospital, Bergen, Norway.,SESAM - Centre for Age-Related Medicine, Stavanger University Hospital, Stavanger, Norway
| | - Annette Fromm
- Department of Neurology, Haukeland University Hospital, Bergen, Norway
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5
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Owusu J, Barrett E. Early Microvascular Dysfunction: Is the Vasa Vasorum a "Missing Link" in Insulin Resistance and Atherosclerosis. Int J Mol Sci 2021; 22:ijms22147574. [PMID: 34299190 PMCID: PMC8303323 DOI: 10.3390/ijms22147574] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/08/2021] [Accepted: 07/10/2021] [Indexed: 11/16/2022] Open
Abstract
The arterial vasa vasorum is a specialized microvasculature that provides critical perfusion required for the health of the arterial wall, and is increasingly recognized to play a central role in atherogenesis. Cardio-metabolic disease (CMD) (including hypertension, metabolic syndrome, obesity, diabetes, and pre-diabetes) is associated with insulin resistance, and characteristically injures the microvasculature in multiple tissues, (e.g., the eye, kidney, muscle, and heart). CMD also increases the risk for atherosclerotic vascular disease. Despite this, the impact of CMD on vasa vasorum structure and function has been little studied. Here we review emerging information on the early impact of CMD on the microvasculature in multiple tissues and consider the potential impact on atherosclerosis development and progression, if vasa vasorum is similarly affected.
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Affiliation(s)
- Jeanette Owusu
- Department of Medicine, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA;
| | - Eugene Barrett
- Department of Medicine, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA;
- Department of Pediatrics, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
- Department of Pharmacology, School of Medicine, University of Virginia, Charlottesville, VA 22908, USA
- Correspondence: ; Tel.: +1-434-924-1263
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6
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Averkiou MA, Bruce MF, Powers JE, Sheeran PS, Burns PN. Imaging Methods for Ultrasound Contrast Agents. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:498-517. [PMID: 31813583 DOI: 10.1016/j.ultrasmedbio.2019.11.004] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 11/05/2019] [Accepted: 11/08/2019] [Indexed: 05/23/2023]
Abstract
Microbubble contrast agents were introduced more than 25 years ago with the objective of enhancing blood echoes and enabling diagnostic ultrasound to image the microcirculation. Cardiology and oncology waited anxiously for the fulfillment of that objective with one clinical application each: myocardial perfusion, tumor perfusion and angiogenesis imaging. What was necessary though at first was the scientific understanding of microbubble behavior in vivo and the development of imaging technology to deliver the original objective. And indeed, for more than 25 years bubble science and imaging technology have evolved methodically to deliver contrast-enhanced ultrasound. Realization of the basic bubbles properties, non-linear response and ultrasound-induced destruction, has led to a plethora of methods; algorithms and techniques for contrast-enhanced ultrasound (CEUS) and imaging modes such as harmonic imaging, harmonic power Doppler, pulse inversion, amplitude modulation, maximum intensity projection and many others were invented, developed and validated. Today, CEUS is used everywhere in the world with clinical indications both in cardiology and in radiology, and it continues to mature and evolve and has become a basic clinical tool that transforms diagnostic ultrasound into a functional imaging modality. In this review article, we present and explain in detail bubble imaging methods and associated artifacts, perfusion quantification approaches, and implementation considerations and regulatory aspects.
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Affiliation(s)
| | - Matthew F Bruce
- Applied Physics Laboratory, University of Washington, Seattle, Washington, USA
| | | | - Paul S Sheeran
- Philips Ultrasound, Bothell, Washington, USA; Knight Cardiovascular Institute, Oregon Health and Science University, Portland, Oregon, USA
| | - Peter N Burns
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; Imaging Research, Sunnybrook Research Institute, Toronto, Ontario, Canada
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7
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Schinkel AFL, Bosch JG, Staub D, Adam D, Feinstein SB. Contrast-Enhanced Ultrasound to Assess Carotid Intraplaque Neovascularization. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:466-478. [PMID: 31791553 DOI: 10.1016/j.ultrasmedbio.2019.10.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/25/2019] [Accepted: 10/28/2019] [Indexed: 06/10/2023]
Abstract
Contrast-enhanced ultrasound (CEUS) is increasingly being used to identify patients with carotid plaques that are vulnerable to rupture, so-called vulnerable atherosclerotic plaques, by assessment of intraplaque neovascularization. A complete overview of the strengths and limitations of carotid CEUS is currently not available. The aim of this systematic review was to provide a complete overview of existing publications on the role of CEUS in assessment of carotid intraplaque neovascularization. The systematic review of the literature yielded 52 studies including a total of 4660 patients (mean age: 66 y, 71% male) who underwent CEUS for the assessment of intraplaque neovascularization. The majority of the patients (76%) were asymptomatic and had no history of transient ischemic attack (TIA) or stroke. The assessment of intraplaque neovascularization was mostly performed using a visual scoring system; several studies used time-intensity curves or dedicated quantification software to optimize analysis. In 17 studies CEUS was performed in patients before carotid surgery (endarterectomy), allowing a comparison of pre-operative CEUS findings with histologic analysis of the tissue sample that is removed from the carotid artery. In a total of 576 patients, the CEUS findings were compared with histopathological analysis of the plaque after surgery. In 16 of the 17 studies, contrast enhancement was found to correlate with the presence and degree of intraplaque neovascularization on histology. Plaques with a larger amount of contrast enhancement had significantly increased density of microvessels in the corresponding region on histology. In conclusion, CEUS is a readily available imaging modality for the assessment of patients with carotid atherosclerosis, providing information on atherosclerotic plaques, such as ulceration and intraplaque neovascularization, which may be clinically relevant. The ultimate clinical goal is the early identification of carotid atherosclerosis to start early preventive therapy and prevent clinical complications such as TIA and stroke.
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Affiliation(s)
- Arend F L Schinkel
- Department of Cardiology, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands.
| | - Johan G Bosch
- Department of Biomedical Engineering, Thoraxcenter, Erasmus MC, Rotterdam, The Netherlands
| | - Daniel Staub
- Division of Angiology, Department of Internal Medicine, University Hospital Basel, Basel, Switzerland
| | - Dan Adam
- Biomedical Engineering, Israel Institute of Technology, Haifa, Israel
| | - Steven B Feinstein
- Section of Cardiology, Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
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8
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Mannaris C, Yang C, Carugo D, Owen J, Lee JY, Nwokeoha S, Seth A, Teo BM. Acoustically responsive polydopamine nanodroplets: A novel theranostic agent. ULTRASONICS SONOCHEMISTRY 2020; 60:104782. [PMID: 31539725 DOI: 10.1016/j.ultsonch.2019.104782] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 08/21/2019] [Accepted: 09/06/2019] [Indexed: 05/06/2023]
Abstract
Ultrasound-induced cavitation has been used as a tool of enhancing extravasation and tissue penetration of anticancer agents in tumours. Initiating cavitation in tissue however, requires high acoustic intensities that are neither safe nor easy to achieve with current clinical systems. The use of cavitation nuclei can however lower the acoustic intensities required to initiate cavitation and the resulting bio-effects in situ. Microbubbles, solid gas-trapping nanoparticles, and phase shift nanodroplets are some examples in a growing list of proposed cavitation nuclei. Besides the ability to lower the cavitation threshold, stability, long circulation times, biocompatibility and biodegradability, are some of the desirable characteristics that a clinically applicable cavitation agent should possess. In this study, we present a novel formulation of ultrasound-triggered phase transition sub-micrometer sized nanodroplets (~400 nm) stabilised with a biocompatible polymer, polydopamine (PDA). PDA offers some important benefits: (1) facile fabrication, as dopamine monomers are directly polymerised on the nanodroplets, (2) high polymer biocompatibility, and (3) ease of functionalisation with other molecules such as drugs or targeting species. We demonstrate that the acoustic intensities required to initiate inertial cavitation can all be achieved with existing clinical ultrasound systems. Cell viability and haemolysis studies show that nanodroplets are biocompatible. Our results demonstrate the great potential of PDA nanodroplets as an acoustically active nanodevice, which is highly valuable for biomedical applications including drug delivery and treatment monitoring.
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Affiliation(s)
- Christophoros Mannaris
- Institute of Biomedical Engineering, Old Road Campus Research Building, University of Oxford, Oxford OX3 7DQ, UK.
| | - Chuanxu Yang
- Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan 250100, China
| | - Dario Carugo
- Institute of Biomedical Engineering, Old Road Campus Research Building, University of Oxford, Oxford OX3 7DQ, UK; Mechatronics and Bioengineering Science Research Groups, Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
| | - Joshua Owen
- Institute of Biomedical Engineering, Old Road Campus Research Building, University of Oxford, Oxford OX3 7DQ, UK
| | - Jeong Yu Lee
- Institute of Biomedical Engineering, Old Road Campus Research Building, University of Oxford, Oxford OX3 7DQ, UK
| | - Sandra Nwokeoha
- Institute of Biomedical Engineering, Old Road Campus Research Building, University of Oxford, Oxford OX3 7DQ, UK
| | - Anjali Seth
- Institute of Biomedical Engineering, Old Road Campus Research Building, University of Oxford, Oxford OX3 7DQ, UK
| | - Boon Mian Teo
- Institute of Biomedical Engineering, Old Road Campus Research Building, University of Oxford, Oxford OX3 7DQ, UK; Key Laboratory of Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan 250100, China; School of Chemistry, Clayton Campus, Monash University Victoria, 3800, Australia.
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9
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Evdokimenko A, Chechetkin A, Druina L, Tanashyan M. Contrast-enhanced ultrasonography for assessing neovascularization of carotid atherosclerotic plaque. BULLETIN OF RUSSIAN STATE MEDICAL UNIVERSITY 2019. [DOI: 10.24075/brsmu.2019.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Neovascularization of a carotid atherosclerotic plaque (AP) is associated with an increased risk of stroke. Contrast-enhanced ultrasonography (CEUS) is a widely used method for imaging intraplaque neovascularization in vivo. Unfortunately, there are no standardized guidelines for CEUS interpretation. The aim of this study was to identify the most reliable method for CEUS-based assessment of AP neovascularization. Seventy-eight AP were removed during carotid endarterectomy in 73 patients, of whom 5 had AP on both sides, and examined morphologically. All patients underwent preoperative duplex scanning and CEUS; Sonovue was used as a contrast agent. AP neovascularization was assessed on a 4-grade visual scale and with 3 different quantitative methods using QLAB software. On the visual scale (method 1), poorly (37%) and moderately (51%) vascularized plaques were the most common. Quantitative analysis (data were presented as Me (Q1; Q3)) revealed that the number of blood vessels per 1 cm2 of the plaque (method 2) was 16 (10; 26), the ratio of the total vessel area to the plaque area (method 3) was 6% (3; 9), and AP ROI (method 4) was 2.6 dB (1.8; 4.1). Significant correlations were demonstrated between the results produced by method 2 and method 3 (р < 0.0001), method 3 and method 2 (p = 0.0006), and between pathomorphological findings and the results produced by methods 1–3, especially method 2 (p < 0.004). AP ROI brightness did not correlate with other results. The presence of hyperechoic components (calcifications) in AP dramatically reduced the reliability of US-based intraplaque neovascularization assessment. The most accurate CEUS-based quantitative method for assessing intraplaque neovascularization is estimation of blood vessel number per 1 cm2 of the plaque.
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Affiliation(s)
| | | | - L.D. Druina
- Research Center of Neurology, Moscow, Russia
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Pereira T, Muguruza J, Mária V, Vilaprinyo E, Sorribas A, Fernandez E, Fernandez-Armenteros JM, Baena JA, Rius F, Betriu A, Solsona F, Alves R. Automatic Methods for Carotid Contrast-Enhanced Ultrasound Imaging Quantification of Adventitial Vasa Vasorum. ULTRASOUND IN MEDICINE & BIOLOGY 2018; 44:2780-2792. [PMID: 30205994 DOI: 10.1016/j.ultrasmedbio.2018.07.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 07/27/2018] [Accepted: 07/29/2018] [Indexed: 06/08/2023]
Abstract
Adventitial vasa vasorum are physiologic microvessels that nourish artery walls. In the presence of cardiovascular risk factors, these microvessels proliferate abnormally. Studies have reported that they are the first stage of atheromatous disease. Contrast-enhanced ultrasound (CEUS) of the carotid allows direct, quantitative and non-invasive visualization of the adventitial vasa vasorum. Hence, the development of computer-assisted methods that speed image analysis and eliminate user subjectivity is important. We developed methods for automatic analyses and quantification of vasa vasorum neovascularization in CEUS and tested these methods in a cohort of 186 individuals, 63 of whom were healthy volunteers. We implemented alternative automatic strategies for using the images to stratify patients according to their risk group and compare the strategies with respect to diagnostic performance. An automatic single-parameter strategy performs less effectively than the corresponding Arcidiacono method based on manual interpretation of the images (68 < area under the receiver operating characteristic curve [AUROC] for the manual Arcidiacono method < 82; 60 < AUROC for the automatic single-parameter strategy < 63). However, by use of additional image parameters, an automatic multiparameter strategy has significantly improved performance with respect to the manual Arcidiacono method (78 < AUROC < 90). The automatic multiparameter strategy is a valuable alternative to the manual Arcidiacono method, improving both diagnostic speed and diagnostic accuracy.
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Affiliation(s)
- Tania Pereira
- Department of Basic Medical Science, University of Lleida, Catalonia, Spain; Institute for Biomedical Research in Lleida, Dr. Pifarré Foundation (IRBLleida), Catalonia, Spain
| | - Jose Muguruza
- Department of Computer Science, University of Lleida, Catalonia, Spain
| | - Virtu Mária
- Unit for the Detection and Treatment of Atherothrombotic Diseases (UDETMA), Hospital Universitari Arnau de Vilanova de Lleida (HUAVL), Catalonia, Spain; Vascular and Renal Translational Research Group, IRBLleida, Catalonia, Spain
| | - Ester Vilaprinyo
- Department of Basic Medical Science, University of Lleida, Catalonia, Spain; Institute for Biomedical Research in Lleida, Dr. Pifarré Foundation (IRBLleida), Catalonia, Spain
| | - Albert Sorribas
- Department of Basic Medical Science, University of Lleida, Catalonia, Spain; Institute for Biomedical Research in Lleida, Dr. Pifarré Foundation (IRBLleida), Catalonia, Spain
| | - Elvira Fernandez
- Unit for the Detection and Treatment of Atherothrombotic Diseases (UDETMA), Hospital Universitari Arnau de Vilanova de Lleida (HUAVL), Catalonia, Spain; Vascular and Renal Translational Research Group, IRBLleida, Catalonia, Spain
| | - Jose Manuel Fernandez-Armenteros
- Institute for Biomedical Research in Lleida, Dr. Pifarré Foundation (IRBLleida), Catalonia, Spain; Servei de Dermatologia, HUAVL and IRBLleida, Catalonia, Spain
| | - Juan Antonio Baena
- Institute for Biomedical Research in Lleida, Dr. Pifarré Foundation (IRBLleida), Catalonia, Spain; Unitat de Cirurgia Endocrina, Bariàtrica i Metabolica, HUAVL and IRBLleida, Catalonia, Spain
| | - Ferran Rius
- Institute for Biomedical Research in Lleida, Dr. Pifarré Foundation (IRBLleida), Catalonia, Spain; Endocrinology and Nutrition Department, HUAVL and IRBLleida, Catalonia, Spain
| | - Angels Betriu
- Unit for the Detection and Treatment of Atherothrombotic Diseases (UDETMA), Hospital Universitari Arnau de Vilanova de Lleida (HUAVL), Catalonia, Spain; Vascular and Renal Translational Research Group, IRBLleida, Catalonia, Spain
| | - Francesc Solsona
- Department of Computer Science, University of Lleida, Catalonia, Spain
| | - Rui Alves
- Department of Basic Medical Science, University of Lleida, Catalonia, Spain; Institute for Biomedical Research in Lleida, Dr. Pifarré Foundation (IRBLleida), Catalonia, Spain.
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11
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D'Oria M, Chiarandini S, Pipitone MD, Fisicaro M, Calvagna C, Bussani R, Rotelli A, Ziani B. Contrast Enhanced Ultrasound (CEUS) Is Not Able to Identify Vulnerable Plaques in Asymptomatic Carotid Atherosclerotic Disease. Eur J Vasc Endovasc Surg 2018; 56:632-642. [PMID: 30193730 DOI: 10.1016/j.ejvs.2018.07.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 07/13/2018] [Indexed: 12/20/2022]
Abstract
OBJECTIVES Contrast enhanced ultrasound (CEUS) has been suggested as an imaging tool for detection of asymptomatic carotid atherosclerotic disease (ACAD) at high risk of cerebral embolisation. The objective of this study was to evaluate CEUS and immunohistochemical (IHC) patterns in ACAD (i.e., without any neurologic symptoms in the last 6 months) and their correlations with histology. METHODS CEUS analysis was classified on a semiquantitative basis using a three-point classification scale. Plaque morphology was assessed using the American Heart Association (AHA) classification of atherosclerotic plaques, then accordingly assigned as non-vulnerable (AHA Type IV/V) or vulnerable (AHA Type VI). IHC analysis for intra-plaque neo-angiogenesis (IPN) was identified by CD34/VEGF immunostaining and classified on a semiquantitative basis using a four-point classification scale. Both CEUS and IHC analyses were performed and scored by single observers. RESULTS Fifty-eight consecutive asymptomatic patients (mean age 73 years, 33 males) undergoing carotid endarterectomy were included in the final analysis. Nineteen had AHA Class IV/V plaques, and the remaining 39 had AHA Class VI plaques. There were two main findings of the study: (a) histologically proven vulnerable plaques compared with histologically proven non-vulnerable plaques had denser IPN (p = .004), but did not show more pronounced contrast enhancement; (b) the correlation between IHC analysis and CEUS analysis was significant for both vulnerable and non-vulnerable plaques (p = .04 and p = .01, respectively), but it was direct for AHA Type IV/V plaques and inverse for AHA Type VI plaques. CONCLUSIONS The main findings of the study were that histologically proven vulnerable plaques (i.e., AHA Class VI) as compared with histologically proven non-vulnerable plaques (i.e., AHA Class IV/V) had denser neo-vascularisation, but not more pronounced contrast enhancement.
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Affiliation(s)
- Mario D'Oria
- Vascular and Endovascular Surgery, Cardiovascular Department, Cattinara Hospital ASUITs, Trieste, Italy.
| | - Stefano Chiarandini
- Vascular and Endovascular Surgery, Cardiovascular Department, Cattinara Hospital ASUITs, Trieste, Italy
| | - Marco D Pipitone
- Vascular and Endovascular Surgery, Cardiovascular Department, Cattinara Hospital ASUITs, Trieste, Italy
| | - Maurizio Fisicaro
- Cardiovascular Health Services Centre, Cardiovascular Department, Maggiore Hospital ASUITs, Trieste, Italy
| | - Cristiano Calvagna
- Vascular and Endovascular Surgery, Cardiovascular Department, Cattinara Hospital ASUITs, Trieste, Italy
| | - Rossana Bussani
- Surgical Pathology, Surgical, Medical and Health Sciences Department, Cattinara Hospital ASUITs, Trieste, Italy
| | - Alice Rotelli
- Vascular and Endovascular Surgery, Cardiovascular Department, Cattinara Hospital ASUITs, Trieste, Italy
| | - Barbara Ziani
- Vascular and Endovascular Surgery, Cardiovascular Department, Cattinara Hospital ASUITs, Trieste, Italy
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12
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Pereira T, Betriu A, Alves R. Non-invasive imaging techniques and assessment of carotid vasa vasorum neovascularization: Promises and pitfalls. Trends Cardiovasc Med 2018; 29:71-80. [PMID: 29970286 DOI: 10.1016/j.tcm.2018.06.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 06/12/2018] [Accepted: 06/14/2018] [Indexed: 12/17/2022]
Abstract
Carotid adventitia vasa vasorum neovascularization (VVn) is associated with the initial stages of arteriosclerosis and with the formation of unstable plaque. However, techniques to accurately quantify that neovascularization in a standard, fast, non-invasive, and efficient way are still lacking. The development of such techniques holds the promise of enabling wide, inexpensive, and safe screening programs that could stratify patients and help in personalized preventive cardiovascular medicine. In this paper, we review the recent scientific literature pertaining to imaging techniques that could set the stage for the development of standard methods for quantitative assessment of atherosclerotic plaque and carotid VVn. We present and discuss the alternative imaging techniques being used in clinical practice and we review the computational developments that are contributing to speed up image analysis and interpretation. We conclude that one of the greatest upcoming challenges will be the use of machine learning techniques to develop automated methods that assist in the interpretation of images to stratify patients according to their risk.
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Affiliation(s)
- T Pereira
- Institute for Biomedical Research in Lleida Dr. Pifarré Foundation, Catalonia, Spain; Departament de Ciències Mèdiques Bàsiques, University of Lleida, Catalonia, Spain.
| | - A Betriu
- Unit for the Detection and Treatment of Atherothrombotic Diseases, Hospital Universitari Arnau de Vilanova de Lleida, Catalonia, Spain; Vascular and Renal Translational Research Group - IRBLleida, Catalonia, Spain
| | - R Alves
- Institute for Biomedical Research in Lleida Dr. Pifarré Foundation, Catalonia, Spain; Departament de Ciències Mèdiques Bàsiques, University of Lleida, Catalonia, Spain
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13
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Oura K, Kato T, Ohba H, Terayama Y. Evaluation of Intraplaque Neovascularization Using Superb Microvascular Imaging and Contrast-Enhanced Ultrasonography. J Stroke Cerebrovasc Dis 2018; 27:2348-2353. [PMID: 29754774 DOI: 10.1016/j.jstrokecerebrovasdis.2018.04.023] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 04/11/2018] [Accepted: 04/19/2018] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Several studies have shown a linkage between intraplaque neovascularization (IPN) and plaque instability. Although contrast-enhanced ultrasonography (CEUS) may help visualize IPN in the carotid artery, its benefits are limited in Japan, where there is no health insurance coverage for contrast agents in medical imaging. Superb microvascular imaging (SMI), however, enables the depiction of low-velocity blood flow. The current study compares the diagnostic accuracy of SMI and CEUS in the evaluation of IPN. METHODS The SMI and CEUS video images were transferred to a workstation and then analyzed to determine whether intraplaque blood flow signals were detected with SMI and whether plaques were contrast-enhanced with carotid artery CEUS. The images generated were independently interpreted by 2 radiologic technologists and 1 neurologist. RESULTS Intraplaque enhancement was observed in 19 patients using CEUS while intraplaque blood flow signals were observed in 12 patients using SMI. A 100% specificity was recorded for SMI (all 12 patients with SMI-detected intraplaque blood flow showed contrast-enhanced plaques), while its sensitivity was 63% (8 of the 15 patients with no SMI-detected intraplaque blood flow showed contrast-enhanced plaques on CEUS). CONCLUSIONS The results of this study show that patients with SMI-detected blood flow will tend to have plaque enhancement using CEUS. This suggests that SMI, as a simpler, safer, and noninvasive technique, can facilitate the visualization of carotid artery IPN without the use of a contrast agent, as well as in the clinical evaluation of plaque instability.
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Affiliation(s)
- Kazumasa Oura
- Division of Neurology and Gerontology, Department of Internal Medicine, School of Medicine, Iwate Medical University, Morioka, Japan.
| | - Tadayoshi Kato
- Division of Neurology and Gerontology, Department of Internal Medicine, School of Medicine, Iwate Medical University, Morioka, Japan
| | - Hideki Ohba
- Division of Neurology and Gerontology, Department of Internal Medicine, School of Medicine, Iwate Medical University, Morioka, Japan
| | - Yasuo Terayama
- Division of Neurology and Gerontology, Department of Internal Medicine, School of Medicine, Iwate Medical University, Morioka, Japan
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14
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Dietrich CF, Averkiou M, Nielsen MB, Barr RG, Burns PN, Calliada F, Cantisani V, Choi B, Chammas MC, Clevert DA, Claudon M, Correas JM, Cui XW, Cosgrove D, D'Onofrio M, Dong Y, Eisenbrey J, Fontanilla T, Gilja OH, Ignee A, Jenssen C, Kono Y, Kudo M, Lassau N, Lyshchik A, Franca Meloni M, Moriyasu F, Nolsøe C, Piscaglia F, Radzina M, Saftoiu A, Sidhu PS, Sporea I, Schreiber-Dietrich D, Sirlin CB, Stanczak M, Weskott HP, Wilson SR, Willmann JK, Kim TK, Jang HJ, Vezeridis A, Westerway S. How to perform Contrast-Enhanced Ultrasound (CEUS). Ultrasound Int Open 2018; 4:E2-E15. [PMID: 29423461 PMCID: PMC5802984 DOI: 10.1055/s-0043-123931] [Citation(s) in RCA: 185] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/27/2017] [Accepted: 11/29/2017] [Indexed: 02/06/2023] Open
Abstract
"How to perform contrast-enhanced ultrasound (CEUS)" provides general advice on the use of ultrasound contrast agents (UCAs) for clinical decision-making and reviews technical parameters for optimal CEUS performance. CEUS techniques vary between centers, therefore, experts from EFSUMB, WFUMB and from the CEUS LI-RADS working group created a discussion forum to standardize the CEUS examination technique according to published evidence and best personal experience. The goal is to standardise the use and administration of UCAs to facilitate correct diagnoses and ultimately to improve the management and outcomes of patients.
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Affiliation(s)
- Christoph F. Dietrich
- Caritas-Krankenhaus, Medizinische Klinik 2, Bad Mergentheim, Germany and Ultrasound Department, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | | | | | - Richard G. Barr
- Radiology, Northeastern Ohio Medical University, Rootstown, United States
| | - Peter N. Burns
- Dept Medical Biophysics, University of Toronto. Sunnybrook Research Institute, Toronto, Canada
| | - Fabrizio Calliada
- Policlinico San Matteo, University of Pavia, Department of Radiology, Pavia, Italy
| | - Vito Cantisani
- Department of Radiology, "Sapienza" University of Rome, ROME, Italy
| | - Byung Choi
- Department of Radiology, Chung-Ang University Hosptial, Seoul, Korea (the Republic of)
| | - Maria C. Chammas
- Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil
| | - Dirk-André Clevert
- Department of Clinical Radiology, University of Munich-Grosshadern Campus, Munich, Germany
| | - Michel Claudon
- Department of Pediatric Radiology, Centre Hospitalier Universitaire de Nancy and Université de Lorraine, Vandoeuvre, France
| | - Jean-Michel Correas
- Hopital universitaire Necker-Enfants malades, Service de Radiologie Adultes, Paris, France
| | - Xin-Wu Cui
- Department of Medical Ultrasound, Tongji Hospital of Tongji Medical college, Huahzong University of Science and technology, Wuhan, China
| | - David Cosgrove
- Imperial College London, Imaging, London, United Kingdom of Great Britain and Northern Ireland
| | | | - Yi Dong
- Department of Ultrasound, Zhongshan Hospital, Fudan University, 200032 Shanghai, China
| | - JohnR. Eisenbrey
- Department of Radiology, Thomas Jefferson University, Philadelphia, United States
| | - Teresa Fontanilla
- Radiology, Hospital Universitario Puerta del Hierro Majadahonda, Majadahonda, Spain
| | - Odd Helge Gilja
- National Centre for Ultrasound in Gastroenterology, Haukeland University Hospital, Bergen and Department of Clinical Medicine, University of Bergen, Norway
| | - Andre Ignee
- Department of Medical Ultrasound, Tongji Hospital of Tongji Medical college, Huahzong University of Science and technology, Wuhan, China
| | - Christian Jenssen
- Krankenhaus Märkisch Oderland Strausberg/ Wriezen, Klinik für Innere Medizin, Wriezen, Germany
| | - Yuko Kono
- Department of Medicine and Radiology, University of California, San Diego, United States
| | - Masatoshi Kudo
- Kinki Daigaku Igakubu, Department Gastroenterology and Hepatology, Osakasayama, Osaka, Japan
| | - Nathalie Lassau
- Gustave Roussy and IR4MUMR8081. Université Paris-Sud, Université Paris-Saclay, Radiology, Paris, France
| | - Andrej Lyshchik
- Department of Radiology, Thomas Jefferson University, Philadelphia, United States
| | - Maria Franca Meloni
- Radiology Department of Interventional Ultrasound - Casa di cura Igea- Milano, Italy
| | - Fuminori Moriyasu
- Sanno Hospital,International University of Helth and Welfare, Center for Cancer Ablation Therapy, Tokyo, Japan
| | - Christian Nolsøe
- Ultrasound Section, Division of Surgery, Dep. of Gastroenterology, Herlev Hospital Copenhagen Academy for Medical Education and Simulation (CAMES), University of Copenhagen, Denmark
| | - Fabio Piscaglia
- Div. Internal Medicine, Dept of Medical and Surgical Sciences, Bologna, Italy
| | - Maija Radzina
- P.Stradina Clinical University Hospital, Diagnosic Radiology Institute, Riga, Latvia
| | - Adrian Saftoiu
- Research Center of Gastroenterology and Hepatology, University of Medicine and Pharmacy of Craiova, Craiova, Romania
| | - Paul S. Sidhu
- King's College London, Radiology, London, United Kingdom of Great Britain and Northern Ireland
| | - Ioan Sporea
- Gastroenterology, University of Medicine and Pharmacy Timisoara, Timisoara, Romania
| | | | - Claude B. Sirlin
- Liver Imaging Grup, University of California, Department of Radiology, San Diego, United States
| | - Maria Stanczak
- Department of Radiology, Thomas Jefferson University, Philadelphia, United States
| | | | - Stephanie R. Wilson
- Department of Radiology, Foothills Medical Centre University of Calgary, Division of Ultrasound, Calgary, Canada
| | | | - Tae Kyoung Kim
- Department of Medical Imaging, University of Toronto, Toronto, Canada
| | - Hyun-Jung Jang
- Department of Medical Imaging, University of Toronto, Toronto, Canada
| | | | - Sue Westerway
- Ultrasound, Charles Sturt University NSW Australia, NSW, Australia
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15
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Baud JM, Luong S, Rouyer O, Maurizot A, Gautier C. [Contribution of contrast enhanced ultrasonography in the characterization of carotid lesions]. JOURNAL DE MEDECINE VASCULAIRE 2017; 42:301-314. [PMID: 28964389 DOI: 10.1016/j.jdmv.2017.06.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 05/19/2017] [Indexed: 06/07/2023]
Abstract
Harmonic mode ultrasound with injection of a contrast enhancement agent allows visualization of mobile microbubbles in the carotid plaque corresponding to neovessels secondary to an inflammation or hypoxia. These neovessels could be considered "precursor" markers of the vulnerable plaque. The aim of this work was to give an update on ultrasound contrast imaging acquisition in the exploration of carotid artery both for atheromatous lesions and for large vessel vasculitis. A precise description of the material to be used, the image acquisition methodology and the environmental conditions is discussed, emphasizing the pitfalls to be avoided as well as proper image interpretation. Microbubbles in a plaque are significantly associated with an increase in cardiovascular events (infarction and acute coronary syndrome) and ipsilateral cerebral ischemic events. Wall irregularities, microfissures and ulcer plaque detection are facilitated by the use of contrast compared to the CT scan. No studies have yet validated contrast enhanced ultrasound in the exploration of asymptomatic carotid stenosis. Contrast enhanced ultrasound also allows to detect vasculitis of the large vessels active phases by the presence of microbubbles in the carotid wall thickening and to monitor the regression under appropriate medical treatment. Future validation studies or even registries are needed to allow better use of this tool in everyday clinical practice.
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Affiliation(s)
- J M Baud
- Unité de médecine vasculaire, service de cardiologie, hôpital André-Mignot, 177, rue de Versailles, 78157 Le Chesnay cedex, France.
| | - S Luong
- Département d'imagerie diagnostique et thérapeutique, hôpital Louis-Pradel, hospices Civils de Lyon, 28, avenue Doyen-Lépine, 69500 Bron, France
| | - O Rouyer
- Unité neurovasculaire, hôpital de Hautepierre, 1, avenue Molière, 67098 Strasbourg cedex, France
| | - A Maurizot
- Unité de médecine vasculaire, service de cardiologie, hôpital André-Mignot, 177, rue de Versailles, 78157 Le Chesnay cedex, France
| | - C Gautier
- Unité fonctionnelle de neurosonologie de l'hôpital Roger-Salengro, service des explorations fonctionnelles cardiovasculaires de l'hôpital cardiologique, CHRU de Lille, rue du Professeur Emile-Laine, 59037 Lille cedex, France
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16
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Yamaguchi Y, Tanaka T, Yoshimura S, Koga M, Nagatsuka K, Toyoda K. A Novel Evaluation for Predicting Aortic Complicated Lesions Using Calcification on Chest X-ray. Cerebrovasc Dis 2017; 44:169-178. [PMID: 28750365 DOI: 10.1159/000479117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Accepted: 06/29/2017] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The aorta is a significant source of cerebral thromboembolisms. Aortic complicated lesions (ACLs) are key findings on transesophageal echocardiography (TEE) for assessing aortic sources of emboli to the brain. TEE is sometimes avoided due to its invasiveness. However, few reports have examined alternative methods for predicting ACLs. We investigated relationships between aortic arch calcification (AAC) on chest X-ray and ACLs. METHODS Participants comprised 300 patients with acute ischemic stroke or transient ischemic attack who underwent TEE for the evaluation of the aortic arch and heart. A postero-anterior plain chest X-ray in the recumbent position was evaluated on admission for each patient. AAC was evaluated using 4 grades (0-3) and "AAC thickness" defined as the distance from the inner margin of the most distant AAC to the outer margin of the aortic vessel wall. ACLs were defined by intima-media thickness (IMT) ≥4.0 mm or presence of ulcerated or mobile plaques. Carotid maximum IMT on ultrasonography was also evaluated. Comparison of the diagnostic ability to predict ACL was performed between AAC grades and AAC thickness or AAC thickness and carotid maximum IMT using the Delong method. RESULTS ACLs were identified in 71 patients (23.7%), including ACLs with ulcerated plaques in 24 (8.0%) and ACLs with mobile plaques in 9 (3.0%). Plaque thickness was greater in higher AAC grades or higher quartiles of AAC thickness (p for trend <0.001 each). The Cochran-Armitage test showed that both higher AAC grade and higher quartile of AAC thickness were significantly associated with the presence of ACLs, as well as the presence of ulcerated or mobile plaques (p for trend < 0.001 each). Receiver-operating characteristic (ROC) analysis showed optimal cut-off values for AAC thickness of 5.6 mm for ACLs and 6.0 mm for ulcerated or mobile plaques. Multivariate logistic regression revealed a higher grade of AAC (grades 2-3) and AAC thickness (≥6 mm) as significantly associated with ACLs and ulcerated or mobile plaques (p < 0.001 each). ROC curve comparisons showed that AAC thickness offered a better marker of ACLs than AAC grade (p = 0.019), although no significant difference was evident between AAC thickness and carotid maximum IMT (p = 0.567). CONCLUSIONS AAC on chest X-ray, evaluated by both AAC grade and AAC thickness to the outer aortic vessel wall, was significantly associated with ACLs on TEE. AAC thickness was suggested as more useful than AAC grade and equivalent to carotid IMT in predicting ACLs.
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Affiliation(s)
- Yoshitaka Yamaguchi
- Department of Cerebrovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
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17
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Preoperative cervical carotid artery contrast-enhanced ultrasound findings are associated with development of microembolic signals on transcranial Doppler during carotid exposure in endarterectomy. Atherosclerosis 2017; 260:87-93. [DOI: 10.1016/j.atherosclerosis.2017.03.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Revised: 02/27/2017] [Accepted: 03/17/2017] [Indexed: 11/20/2022]
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18
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Schmidt C, Fischer T, Rückert RI, Oberwahrenbrock T, Harms L, Kronenberg G, Kunte H. Identification of neovascularization by contrast-enhanced ultrasound to detect unstable carotid stenosis. PLoS One 2017; 12:e0175331. [PMID: 28388659 PMCID: PMC5384678 DOI: 10.1371/journal.pone.0175331] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 03/25/2017] [Indexed: 12/14/2022] Open
Abstract
Background Plaque neovascularization accompanies local inflammation and critically contributes to plaque instability. Correct identification of intraplaque neovascularization by contrast–enhanced ultrasound (CEUS) may provide an additional risk marker in carotid stenosis. This pilot study investigates the correlation between histological evaluation of carotid plaque specimens and pre-surgery CEUS to identify neovascularization. Methods 17 patients with high-grade internal carotid artery (ICA) stenosis were studied. CEUS was performed in all patients shortly before carotid endarterectomy. Neovascularization, infiltration of T cells and macrophages along with intraplaque hemorrhage were studied in excised plaques by immunohistochemistry. Ultrasound-based four-level and two-level classification systems for neovascularization were used. CEUS findings were compared with histological findings. Results Scores on the CEUS-based four-level and two-level classifications were robustly correlated with the density of intraplaque vessels (r = 0.635, p = 0.006 and r = 0.578, p = 0.015, respectively). Histological evaluation of regions with strong and prolonged intraplaque enhancement typically showed strong intraplaque neovascularization in conjunction with acute intraplaque hemorrhage. Moreover, higher grades of intraplaque neovascularization as determined by ultrasound were associated with a higher percentage of macrophage-rich areas. Conclusion CEUS is a technique well suited to gauge the degree of neovascularization of carotid plaques. Future research will have to define the reliability and validity of CEUS in everyday clinical practice. Further, our study suggests that CEUS may also be useful to pick up features of vulnerable plaques such as acute intraplaque hemorrhages.
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Affiliation(s)
- Charlotte Schmidt
- Charité Center 15 for Neurology, Neurosurgery and Psychiatry, Charité –Universitätsmedizin Berlin, Berlin, Germany
| | - Thomas Fischer
- Institute of Radiology, Charité –Universitätsmedizin Berlin, Berlin, Germany
| | | | - Timm Oberwahrenbrock
- NeuroCure Clinical Research Center, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Lutz Harms
- Charité Center 15 for Neurology, Neurosurgery and Psychiatry, Charité –Universitätsmedizin Berlin, Berlin, Germany
| | - Golo Kronenberg
- Charité Center 15 for Neurology, Neurosurgery and Psychiatry, Charité –Universitätsmedizin Berlin, Berlin, Germany
- Klinik und Poliklinik für Psychiatrie und Psychotherapie, Zentrum für Nervenheilkunde, Universitätsmedizin Rostock, Rostock, Germany
| | - Hagen Kunte
- Charité Center 15 for Neurology, Neurosurgery and Psychiatry, Charité –Universitätsmedizin Berlin, Berlin, Germany
- MSB Medical School Berlin, Berlin, Germany
- * E-mail:
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19
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Germanò G, Macchioni P, Possemato N, Boiardi L, Nicolini A, Casali M, Versari A, Pipitone N, Salvarani C. Contrast-Enhanced Ultrasound of the Carotid Artery in Patients With Large Vessel Vasculitis: Correlation With Positron Emission Tomography Findings. Arthritis Care Res (Hoboken) 2016; 69:143-149. [DOI: 10.1002/acr.22906] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 02/08/2016] [Accepted: 03/29/2016] [Indexed: 11/06/2022]
Affiliation(s)
| | | | | | - Luigi Boiardi
- Azienda Ospedaliera IRCCS di Reggio Emilia; Reggio Emilia Italy
| | | | | | | | - Nicolò Pipitone
- Azienda Ospedaliera IRCCS di Reggio Emilia; Reggio Emilia Italy
| | - Carlo Salvarani
- Azienda Ospedaliera IRCCS di Reggio Emilia; Reggio Emilia Italy
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20
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Gujral DM, Cheung WK, Shah BN, Chahal NS, Bhattacharyya S, Hooper J, Senior R, Tang MX, Harrington KJ, Nutting CM. Contrast enhancement of carotid adventitial vasa vasorum as a biomarker of radiation-induced atherosclerosis. Radiother Oncol 2016; 120:63-8. [PMID: 27370203 DOI: 10.1016/j.radonc.2016.06.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Revised: 06/15/2016] [Accepted: 06/18/2016] [Indexed: 11/25/2022]
Abstract
PURPOSE Abnormal proliferation of adventitial vasa vasorum (vv) occurs early at sites of atherosclerosis and is thought to be an early biomarker of vascular damage. Contrast-enhanced ultrasound (CEUS) can detect this process. Its usefulness in irradiated arteries as a measure of accelerated atherosclerosis is unknown. This study investigates contrast intensity in carotid adventitia as an early marker of radiation-induced damage in head and neck cancer (HNC) patients. MATERIALS/METHODS Patients with HNC treated with a wedged-pair and matched neck technique or hemi-neck radiotherapy (RT) (unirradiated side as control) at least 2years previously were included. Patients had been prescribed a dose of at least 50Gy to the neck. CEUS was performed on both carotid arteries and a region of interest was selected in the adventitia of the far wall of both left and right distal common carotid arteries. Novel quantification software was used to compare the average intensity per pixel between irradiated and unirradiated arteries. RESULTS 48 patients (34 males) with median age of 59.2years (interquartile range (IQR) 49.2-64.2) were included. The mean maximum point dose to the irradiated artery was 61.2Gy (IQR 52.6-61.8) and 1.1Gy (IQR 1.0-1.8Gy) to the unirradiated side. The median interval from RT was 59.4months (IQR 41-88.7). There was a significant difference in the mean (SD) contrast intensity per pixel on the irradiated side (1.1 (0.4)) versus 0.96 (0.34) on the unirradiated side (p=0.01). After attenuation correction, the difference in mean contrast intensity per pixel was still significant (1.4 (0.58) versus 1.2 (0.47) (p=0.02). Previous surgery or chemotherapy had no effect on the difference in contrast intensity between the 2 sides of the neck. Mean intensity per pixel did not correlate to traditional risk prediction models (carotid intima-medial thickness, QSTROKE score). CONCLUSIONS Proliferation of vv is demonstrated by increased contrast intensity in irradiated carotid arteries. This may be a useful, independent biomarker of radiation-induced carotid atherosclerosis when used as a tool to quantify neovascularization.
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Affiliation(s)
| | | | - Benoy N Shah
- Department of Echocardiography, Royal Brompton Hospital, London, UK
| | - Navtej S Chahal
- Department of Echocardiography, Royal Brompton Hospital, London, UK
| | | | - James Hooper
- Department of Biochemistry, Royal Brompton Hospital, London, UK
| | - Roxy Senior
- Department of Echocardiography, Royal Brompton Hospital, London, UK
| | - Meng-Xing Tang
- Department of Bioengineering, Imperial College, London, UK
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21
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Huang R, Abdelmoneim SS, Ball CA, Nhola LF, Farrell AM, Feinstein S, Mulvagh SL. Detection of Carotid Atherosclerotic Plaque Neovascularization Using Contrast Enhanced Ultrasound: A Systematic Review and Meta-Analysis of Diagnostic Accuracy Studies. J Am Soc Echocardiogr 2016; 29:491-502. [PMID: 27038513 DOI: 10.1016/j.echo.2016.02.012] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Indexed: 11/27/2022]
Abstract
BACKGROUND Intraplaque neovascularization is considered an important indicator of plaque vulnerability. Contrast-enhanced ultrasound (CEUS) of carotid arteries improves imaging of carotid intima-media thickness and permits real-time visualization of neovascularization of the atherosclerotic plaque. The authors conducted a systematic review and meta-analysis to evaluate the accuracy of CEUS-detected carotid atherosclerotic plaque. METHODS A systematic search was performed to identify studies published in the MEDLINE, Embase, Scopus, and Web of Science databases from 2004 to June 2015. Studies evaluating the accuracy of quantitative analysis and qualitative analysis (visual interpretation) for the diagnosis of intraplaque neovascularization compared with histologic specimens and/or clinical diagnosis of symptomatic plaque were included. Parameters evaluated were plaque quantitative CEUS intensity and the visual grading of plaque CEUS. A random-effects meta-analysis was used to pool the likelihood ratios (LRs), diagnostic odds ratios, and summary receiver operating characteristic curves. Corresponding areas under the curves were calculated. RESULTS The literature search identified 203 studies, 20 of which were selected for systematic review; the final meta-analysis included seven studies. For qualitative CEUS, pooled sensitivity was 0.80 (95% CI, 0.72-0.87), pooled specificity was 0.83 (95% CI, 0.76-0.89), the pooled positive LR was 3.22 (95% CI, 1.67-6.18), the pooled negative LR was 0.24 (95% CI, 0.09-0.64), the pooled diagnostic odds ratio was 15.57 (95% CI, 4.94-49.03), and area under the curve was 0.894. For quantitative CEUS, pooled sensitivity was 0.77 (95% CI, 0.71-0.83), pooled specificity was 0.68 (95% CI, 0.62-0.73), the pooled positive LR was 2.34 (95% CI, 1.69-3.23), the pooled negative LR was 0.34 (95% CI, 0.25-0.47), the pooled diagnostic odds ratio was 7.06 (95% CI, 3.6-13.82), and area under the curve was 0.888. CONCLUSIONS CEUS is a promising noninvasive diagnostic modality for detecting intraplaque neovascularization. Standardization of quantitative analysis and visual grading classification is needed to increase reliability and reduce technical heterogeneity.
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Affiliation(s)
- Runqing Huang
- Division of Cardiovascular Diseases, Mayo Clinic Cardiovascular Ultrasound Imaging and Hemodynamic Laboratory, Mayo Clinic, Rochester, Minnesota; Division of Ultrasound, Tongji Hospital, Tongji Medical College, HuaZhong University of Science and Technology, Wuhan, China
| | - Sahar S Abdelmoneim
- Division of Cardiovascular Diseases, Mayo Clinic Cardiovascular Ultrasound Imaging and Hemodynamic Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Caroline A Ball
- Internal Medicine, Mayo Clinic Cardiovascular Ultrasound Imaging and Hemodynamic Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Lara F Nhola
- Division of Cardiovascular Diseases, Mayo Clinic Cardiovascular Ultrasound Imaging and Hemodynamic Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Ann M Farrell
- Mayo Clinic Libraries, Mayo Clinic Cardiovascular Ultrasound Imaging and Hemodynamic Laboratory, Mayo Clinic, Rochester, Minnesota
| | | | - Sharon L Mulvagh
- Division of Cardiovascular Diseases, Mayo Clinic Cardiovascular Ultrasound Imaging and Hemodynamic Laboratory, Mayo Clinic, Rochester, Minnesota.
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Christofides D, Leen E, Averkiou MA. Evaluation of the Accuracy of Liver Lesion DCEUS Quantification With Respiratory Gating. IEEE TRANSACTIONS ON MEDICAL IMAGING 2016; 35:622-629. [PMID: 26452276 DOI: 10.1109/tmi.2015.2487866] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Confidence in the accuracy of dynamic contrast enhanced ultrasound (DCEUS) quantification parameters is imperative for the correct diagnosis of liver lesion perfusion characteristics. An important source of uncertainty in liver DCEUS acquisitions is artifacts introduced by respiratory motion. The objective of this study is to construct a respiratory motion simulation model (RMSM) of dual contrast imaging mode acquisitions of liver lesions in order to evaluate an algorithm for automatic respiratory gating (ARG). The respiratory kinetics as well as the perfusion models of the liver lesion and parenchyma used by the RMSM were solely derived from clinical data. The quality of fit (of the DCEUS data onto the bolus kinetics model) depends on the respiration amplitude. Similar trends in terms of quality of fit as a function of respiration amplitude were observed from RMSM and clinical data. The errors introduced on the DCEUS quantification under the influence of respiration were evaluated. The RMSM revealed that the error in the liver lesion DCEUS quantification parameters significantly decreased (p < 0.001) from a maximum of 32.3% to 6.2% when ARG was used. The use of RMSM clearly demonstrates the capability of the ARG algorithm in significantly reducing errors introduced from both in-plane and out-of-plane respiratory motion.
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Renaud G, Bosch JG, van der Steen AFW, de Jong N. Increasing specificity of contrast-enhanced ultrasound imaging using the interaction of quasi counter-propagating wavefronts: a proof of concept. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2015; 62:1768-1778. [PMID: 26470039 DOI: 10.1109/tuffc.2015.007169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Detection methods implemented in present clinical ultrasound scanners for contrast-enhanced ultrasound imaging show high sensitivity but a rather poor specificity due to pseudo-enhancement (false detection of contrast agent) produced by nonlinear wave propagation. They all require linear ultrasound propagation to detect nonlinear scattering of contrast agent microbubbles. Even at low transmit pressure, nonlinear wave propagation occurs in regions perfused with contrast agent because contrast agent microbubbles can dramatically enhance the nonlinear elastic behavior of the medium. This image artifact hinders further development of contrast-enhanced ultrasound imaging toward reliable quantitative measurement of local concentration of contrast agent and blood perfusion kinetics. We propose in this manuscript a new detection method, with specific beamforming and pulsing scheme, that produces contrast images with highly reduced pseudo-enhancement. It is based on the interaction of two diverging wavefronts broadcasted by two single elements of a conventional probe array. The contrast image is formed line by line; one single image line is the line segment bisector defined by the centers of the two transmitting elements. Each image line is formed by a three-step pulse sequence: (1) transmission with one element, (2) transmission with the other element, and (3) transmission with both elements. The proof of principle is shown with numerical simulations and in vitro experiments. The method is implemented in a programmable ultrasound system and tested in a tissue-mimicking phantom containing a vessel filled with diluted contrast agent. At a given depth, increasing the distance between the two transmitting elements increases the angle describing the propagation directions of the two wavefronts. As a result, the nonlinear interaction between the two broadcasted waves is reduced. We show experimentally that increasing the distance between the transmitting elements from 0.6 to 24 mm reduces the amplitude of the pseudoenhancement at the far wall of the vessel relative to true contrast signal amplitude in the vessel by 12 dB, therefore improving specificity in the contrast-enhanced image.
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Zhang Q, Li C, Zhou M, Liao Y, Huang C, Shi J, Wang Y, Wang W. Quantification of carotid plaque elasticity and intraplaque neovascularization using contrast-enhanced ultrasound and image registration-based elastography. ULTRASONICS 2015; 62:253-262. [PMID: 26074459 DOI: 10.1016/j.ultras.2015.05.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 05/18/2015] [Accepted: 05/29/2015] [Indexed: 06/04/2023]
Abstract
It is valuable for evaluation of carotid plaque vulnerability to investigate the relation between intraplaque neovascularization (IPN) and plaque elasticity. The contrast-enhanced ultrasound (CEUS) has been used in IPN measurement, but it cannot assess plaque elasticity. The aim of this study was to develop an ultrasound elastography technique based on registration of CEUS sequential images and to use this technique for direct comparison between IPN and plaque elasticity. We employed a nonrigid image registration method using the free-form deformation model to register a pair of clinical CEUS images at systole and diastole. The 2D displacement field of the plaque was estimated and then utilized to calculate the axial and lateral strain distributions within the plaque, from which quantitative strain parameters were obtained. The IPN was measured semiquantitatively with visual assessment and quantitatively with the time-intensity curve analysis and the analysis of contrast agent spatial distributions. Histopathology with CD34 staining for quantification of microvessel density (MVD) was performed on plaques excised by carotid endarterectomy. Simulation experiments showed that the mean absolute error and the root mean squared error of the displacement estimation were 0.325±0.180 pixel (7.2%±3.8%) and 0.556±0.284 pixel (12.3%±6.1%), respectively, demonstrating high accuracy of the elastography technique. Thirty-eight plaques in 29 patients met the inclusion criteria for the elastography and image analysis, where ten plaques underwent endarterectomy. The 95th percentile (A95) and standard deviation (Asd) of the axial strains exhibited significant differences between the low and high grades of IPN visually assessed (p<0.01). A95 (R=0.579; p<0.001) and Asd (R=0.609; p<0.001) were correlated with the enhanced intensity of plaque, and also correlated with the MVD (R=0.793 and 0.817, respectively; p<0.01), suggesting that plaque became softer and more elastically heterogeneous as IPN increased. These findings provide direct and quantitative evidence for the associations between plaque strains and IPN and might be helpful for evaluation of carotid plaque vulnerability and for plaque risk stratification.
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Affiliation(s)
- Qi Zhang
- School of Communication and Information Engineering, Shanghai University, 200444 Shanghai, China.
| | - Chaolun Li
- Department of Ultrasound, Zhongshan Hospital, Fudan University, 200032 Shanghai, China.
| | - Moli Zhou
- School of Communication and Information Engineering, Shanghai University, 200444 Shanghai, China
| | - Yu Liao
- School of Communication and Information Engineering, Shanghai University, 200444 Shanghai, China
| | - Chunchun Huang
- School of Communication and Information Engineering, Shanghai University, 200444 Shanghai, China
| | - Jun Shi
- School of Communication and Information Engineering, Shanghai University, 200444 Shanghai, China.
| | - Yuanyuan Wang
- Department of Electronic Engineering, Fudan University, 200433 Shanghai, China.
| | - Wenping Wang
- Department of Ultrasound, Zhongshan Hospital, Fudan University, 200032 Shanghai, China.
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Spatio-temporal Quantification of Carotid Plaque Neovascularization on Contrast Enhanced Ultrasound: Correlation with Visual Grading and Histopathology. Eur J Vasc Endovasc Surg 2015. [PMID: 26211685 DOI: 10.1016/j.ejvs.2015.06.077] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE/BACKGROUND To evaluate whether carotid intraplaque neovascularization (IPN) can be accurately assessed by two types of quantitative analysis on contrast enhanced ultrasound (CEUS), the time intensity curve analysis and the analysis of contrast agent spatial distributions, and whether the quantitative analysis correlates with semiquantitative visual interpretation and histopathology. METHODS Forty-four plaques in 34 patients were included for CEUS examination. A three point score system (absent, moderate, and extensive) was used for semiquantitative grading of IPN. Eight spatial quantitative parameters were derived, including the IPN area ratio in plaque (AR) and the AR in plaque core (AR13). Two temporal quantitative parameters were obtained, namely the enhanced intensity in plaque (EI) and the enhanced intensity ratio (EIR). Histopathology with CD34 staining for quantification of microvessel density (MVD) was performed on 12 plaques excised by carotid endarterectomy. RESULTS Both spatial and temporal parameters were correlated with MVD on histology (AR: r = .854; AR13: r = .858; EI: r = .767; EIR: r = .750 [p < .01]), as well as with semiquantitative grading (p < .01). Five mutually independent factors were condensed from 10 interrelated parameters by using factor analysis, and they significantly predicted MVD with an radj value as high as .932 (p = .01). CONCLUSION Both spatial and temporal analysis on CEUS can accurately assess IPN. Combining them provides better IPN assessment and may be useful for plaque vulnerability evaluation and risk stratification.
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Assessment of carotid plaque neovascularization using quantitative analysis of contrast-enhanced ultrasound imaging is useful for risk stratification in patients with coronary artery disease. Int J Cardiol 2015; 195:113-9. [PMID: 26025869 DOI: 10.1016/j.ijcard.2015.05.107] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Revised: 04/13/2015] [Accepted: 05/06/2015] [Indexed: 01/25/2023]
Abstract
BACKGROUND Contrast-enhanced ultrasound (CEUS) of the carotid artery is a potential technique for imaging plaque neovascularization, a feature of unstable atherosclerotic plaques. This study examined whether assessment of intra-plaque neovascularization of the carotid artery using CEUS provides prognostic information in patients with coronary artery disease (CAD). METHODS A total of 206 patients with stable CAD underwent a CEUS examination of the carotid artery and were followed up prospectively for <38 months or until a cardiac event (cardiac death, non-fatal myocardial infarction (MI), unstable angina pectoris (uAP) requiring unplanned coronary revascularization, or heart failure requiring hospitalization). The degree of contrast signals measured within the carotid plaque was quantified by calculating the mean gray scale level within the region of interest of the carotid plaque, expressed as plaque enhanced intensity. RESULTS During the follow-up period, 31 events occurred (2 cardiac deaths, 7 non-fatal MIs, 16 uAP, and 6 heart failure). Multivariate Cox proportional hazard analysis showed that plaque enhanced intensity was a significant predictor of cardiac events independent of traditional risk factors (HR, 1.13; 95% CI, 1.05-1.21; p<0.001). The addition of the plaque enhanced intensity to traditional risk factors resulted in net reclassification improvement (NRI) and integrated discrimination improvement (IDI) (NRI 0.62, p=0.001; and IDI 0.106, p=0.002). CONCLUSIONS The assessment of carotid plaque neovascularization using quantitative analysis of CEUS may be useful for risk stratification in patients with CAD.
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Iezzi R, Petrone G, Ferrante A, Lauriola L, Vincenzoni C, la Torre MF, Snider F, Rindi G, Bonomo L. The role of contrast-enhanced ultrasound (CEUS) in visualizing atherosclerotic carotid plaque vulnerability: Which injection protocol? Which scanning technique? Eur J Radiol 2015; 84:865-71. [DOI: 10.1016/j.ejrad.2015.01.024] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 01/14/2015] [Accepted: 01/30/2015] [Indexed: 01/30/2023]
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Improvement of the accuracy of liver lesion DCEUS quantification with the use of automatic respiratory gating. Eur Radiol 2015; 26:417-24. [DOI: 10.1007/s00330-015-3797-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 04/05/2015] [Accepted: 04/13/2015] [Indexed: 10/23/2022]
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van Rooij T, Daeichin V, Skachkov I, de Jong N, Kooiman K. Targeted ultrasound contrast agents for ultrasound molecular imaging and therapy. Int J Hyperthermia 2015; 31:90-106. [PMID: 25707815 DOI: 10.3109/02656736.2014.997809] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Ultrasound contrast agents (UCAs) are used routinely in the clinic to enhance contrast in ultrasonography. More recently, UCAs have been functionalised by conjugating ligands to their surface to target specific biomarkers of a disease or a disease process. These targeted UCAs (tUCAs) are used for a wide range of pre-clinical applications including diagnosis, monitoring of drug treatment, and therapy. In this review, recent achievements with tUCAs in the field of molecular imaging, evaluation of therapy, drug delivery, and therapeutic applications are discussed. We present the different coating materials and aspects that have to be considered when manufacturing tUCAs. Next to tUCA design and the choice of ligands for specific biomarkers, additional techniques are discussed that are applied to improve binding of the tUCAs to their target and to quantify the strength of this bond. As imaging techniques rely on the specific behaviour of tUCAs in an ultrasound field, it is crucial to understand the characteristics of both free and adhered tUCAs. To image and quantify the adhered tUCAs, the state-of-the-art techniques used for ultrasound molecular imaging and quantification are presented. This review concludes with the potential of tUCAs for drug delivery and therapeutic applications.
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Affiliation(s)
- Tom van Rooij
- Department of Biomedical Engineering, Thoraxcenter , Erasmus MC, Rotterdam , the Netherlands
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Daeichin V, Bosch JG, Needles A, Foster FS, van der Steen A, de Jong N. Subharmonic, non-linear fundamental and ultraharmonic imaging of microbubble contrast at high frequencies. ULTRASOUND IN MEDICINE & BIOLOGY 2015; 41:486-97. [PMID: 25592458 DOI: 10.1016/j.ultrasmedbio.2014.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 09/11/2014] [Accepted: 10/08/2014] [Indexed: 05/24/2023]
Abstract
There is increasing use of ultrasound contrast agent in high-frequency ultrasound imaging. However, conventional contrast detection methods perform poorly at high frequencies. We performed systematic in vitro comparisons of subharmonic, non-linear fundamental and ultraharmonic imaging for different depths and ultrasound contrast agent concentrations (Vevo 2100 system with MS250 probe and MicroMarker ultrasound contrast agent, VisualSonics, Toronto, ON, Canada). We investigated 4-, 6- and 10-cycle bursts at three power levels with the following pulse sequences: B-mode, amplitude modulation, pulse inversion and combined pulse inversion/amplitude modulation. The contrast-to-tissue (CTR) and contrast-to-artifact (CAR) ratios were calculated. At a depth of 8 mm, subharmonic pulse-inversion imaging performed the best (CTR = 26 dB, CAR = 18 dB) and at 16 mm, non-linear amplitude modulation imaging was the best contrast imaging method (CTR = 10 dB). Ultraharmonic imaging did not result in acceptable CTRs and CARs. The best candidates from the in vitro study were tested in vivo in chicken embryo and mouse models, and the results were in a good agreement with the in vitro findings.
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Affiliation(s)
- Verya Daeichin
- Biomedical Engineering, Thorax Center, Erasmus MC, Rotterdam, The Netherlands.
| | - Johan G Bosch
- Biomedical Engineering, Thorax Center, Erasmus MC, Rotterdam, The Netherlands
| | | | - F Stuart Foster
- Sunnybrook Research Institute and Department of Medical Biophysics, University of Toronto, Toronto, Canada
| | - Antonius van der Steen
- Biomedical Engineering, Thorax Center, Erasmus MC, Rotterdam, The Netherlands; Technical University Delft, Delft, The Netherlands
| | - Nico de Jong
- Biomedical Engineering, Thorax Center, Erasmus MC, Rotterdam, The Netherlands; Technical University Delft, Delft, The Netherlands; Interuniversity Cardiology Institute of the Netherlands, Utrecht, The Netherlands
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Keravnou CP, Mannaris C, Averkiou MA. Accurate measurement of microbubble response to ultrasound with a diagnostic ultrasound scanner. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2015; 62:176-184. [PMID: 25585401 DOI: 10.1109/tuffc.2014.006664] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ultrasound and microbubbles are often used to enhance drug delivery and the suggested mechanisms are extravasation and sonoporation. Drug delivery schemes with ultrasound and microbubbles at both low and high acoustic amplitudes have been suggested. A diagnostic ultrasound scanner may play a double role as both an imaging and a therapy device. It was not possible to accurately measure microbubble response with an ultrasound scanner for a large range of acoustic pressures and microbubble concentrations until now, mainly because of signal saturation issues. A method for continuously adjusting the receive gain of a scanner and limiting signal saturation was developed to accurately measure backscattered echoes from microbubbles for mechanical indexes (MIs) up to 2.1. The intensity of backscattered echoes from microbubbles increased quarticly with MI without reaching any limit. The signal intensity from microbubbles was found to be linear with concentration at both low and high MIs. However, at very high concentrations, acoustic shadowing occurs which limits the delivered acoustic pressure in deeper areas. The contrastto- tissue ratio was also measured and found to stay constant with MI. These results can be used to better guide drug delivery approaches and to also develop imaging techniques for therapy procedures.
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Sun J, Deng YB, Liu K, Wang YB. Effects of noradrenaline and adenosine triphosphate on the degree on contrast enhancement in a rabbit model of atherosclerosis during contrast-enhanced ultrasonography. ULTRASOUND IN MEDICINE & BIOLOGY 2014; 40:2655-2661. [PMID: 25218451 DOI: 10.1016/j.ultrasmedbio.2014.06.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Revised: 06/04/2014] [Accepted: 06/09/2014] [Indexed: 06/03/2023]
Abstract
The aim of the study is to assess the effects of vasoactive agents on the degree of contrast enhancement in experimental atherosclerotic plaque during contrast-enhanced ultrasonography (CEUS). Abdominal aortic atherosclerosis was induced in 25 New Zealand white rabbits by a combination of cholesterol-rich diet and balloon endothelial denudation. Standard ultrasonography and CEUS were performed at baseline and during intravenous infusion of noradrenaline or adenosine triphosphate (ATP). The degree of contrast enhancement of the plaque after injection of contrast material was quantified by calculating the enhanced intensity in the plaque. The infusion of noradrenaline induced significant increase in systolic blood pressure (84 ± 13 mm Hg vs. 112 ± 20 mm Hg, p = 0.011) and significant decrease in the enhanced intensity in the plaque (7.52 ± 1.32 dB vs. 5.88 ± 1.33 dB, p < 0.001) during CEUS. The infusion of ATP resulted in the significant decrease in systolic blood pressure (80 ± 13 mm Hg vs. 65 ± 11 mm Hg, p = 0.005) and increase in the enhanced intensity in the plaque (7.52 ± 1.32 dB vs. 8.84 ± 1.55 dB, p < 0.001) during CEUS. The degree of contrast enhancement within an experimental atherosclerotic plaque during CEUS can be influenced by vasoactive agents and hemodynamic status.
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Affiliation(s)
- Jie Sun
- Department of Medical Ultrasound, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - You-Bin Deng
- Department of Medical Ultrasound, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
| | - Kun Liu
- Department of Medical Ultrasound, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yu-Bo Wang
- Department of Medical Ultrasound, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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van den Oord SCH, Akkus Z, Renaud G, Bosch JG, van der Steen AFW, Sijbrands EJG, Schinkel AFL. Assessment of carotid atherosclerosis, intraplaque neovascularization, and plaque ulceration using quantitative contrast-enhanced ultrasound in asymptomatic patients with diabetes mellitus. Eur Heart J Cardiovasc Imaging 2014; 15:1213-8. [PMID: 24972806 DOI: 10.1093/ehjci/jeu127] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS Patients with diabetes mellitus (DM) are at severely increased risk of developing atherosclerosis. Intraplaque neovascularization (IPN) and plaque ulceration are markers of the vulnerable plaque, which is at an increased risk of rupture and may lead to cardiovascular events. The aim of this study was to assess the prevalence of subclinical carotid atherosclerosis, intraplaque neovascularization (IPN), and plaque ulceration in asymptomatic patients with DM. METHODS AND RESULTS A total of 51 asymptomatic patients with DM underwent standard carotid ultrasound in conjunction with contrast-enhanced ultrasound (CEUS) to assess the prevalence of subclinical atherosclerosis, IPN, and plaque ulceration. Subclinical atherosclerosis was defined as the presence of atherosclerotic plaque, according to the Mannheim consensus. Semi-automated quantification software was used to assess IPN in suitable plaques. Plaque ulceration was defined as a disruption of the plaque-lumen border of ≥ 1 × 1 mm. A total of 408 carotid segments in 102 carotid arteries were investigated. Forty-six (90%) patients had subclinical atherosclerotic plaques, with a median plaque thickness of 2.4 mm (inter-quartile range 1.9-3.0). CEUS revealed IPN in 88% of the patients. In 10 carotid segments (8%), the plaque had an ulcerated surface. The presence of IPN could not be predicted by the presence of clinical characteristics including complications of DM (P > 0.05). CONCLUSION Patients with DM have a high prevalence (90%) of subclinical carotid atherosclerosis. Severe IPN and plaque ulceration, which are markers of the vulnerable plaque type, were detected in, respectively, 13 and 9% of these patients.
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Affiliation(s)
- Stijn C H van den Oord
- Department of Cardiology, Thoraxcenter, Erasmus Medical Center, Thoraxcenter Room Ba304, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Zeynettin Akkus
- Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Guillaume Renaud
- Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Johan G Bosch
- Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | - Eric J G Sijbrands
- Division of Pharmacology, Vascular and Metabolic Diseases, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Arend F L Schinkel
- Department of Cardiology, Thoraxcenter, Erasmus Medical Center, Thoraxcenter Room Ba304, 's-Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands
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van den Oord SC, van der Burg J, Akkus Z, Bosch JG, van Domburg RT, Sijbrands EJ, van der Steen AF, Schinkel AF. Impact of gender on the density of intraplaque neovascularization: A quantitative contrast-enhanced ultrasound study. Atherosclerosis 2014; 233:461-466. [DOI: 10.1016/j.atherosclerosis.2013.12.054] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 12/10/2013] [Accepted: 12/29/2013] [Indexed: 11/30/2022]
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Akkus Z, Hoogi A, Renaud G, van den Oord SCH, Ten Kate GL, Schinkel AFL, Adam D, de Jong N, van der Steen AFW, Bosch JG. New quantification methods for carotid intra-plaque neovascularization using contrast-enhanced ultrasound. ULTRASOUND IN MEDICINE & BIOLOGY 2014; 40:25-36. [PMID: 24161799 DOI: 10.1016/j.ultrasmedbio.2013.09.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 08/21/2013] [Accepted: 09/01/2013] [Indexed: 06/02/2023]
Abstract
As carotid intra-plaque neovascularization (IPN) is linked to progressive atherosclerotic disease and plaque vulnerability, its accurate quantification might allow early detection of plaque vulnerability. We therefore developed several new quantitative methods for analyzing IPN perfusion and structure. From our analyses, we derived six quantitative parameters-IPN surface area (IPNSA), IPN surface ratio (IPNSR), plaque mean intensity, plaque-to-lumen enhancement ratio, mean plaque contrast percentage and number of micro-vessels (MVN)-and compared these with visual grading of IPN by two independent physicians. A total of 45 carotid arteries with symptomatic stenosis in 23 patients were analyzed. IPNSA (correlation r = 0.719), IPNSR (r = 0.538) and MVN (r = 0.484) were found to be significantly correlated with visual scoring (p < 0.01). IPNSA was the best match to visual scoring. These results indicate that IPNSA, IPNSR and MVN may have the potential to replace qualitative visual scoring and to measure the degree of carotid IPN.
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Affiliation(s)
- Zeynettin Akkus
- Department of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands
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Schinkel AFL, van den Oord SCH, van der Steen AFW, van Laar JAM, Sijbrands EJG. Utility of contrast-enhanced ultrasound for the assessment of the carotid artery wall in patients with Takayasu or giant cell arteritis. Eur Heart J Cardiovasc Imaging 2013; 15:541-6. [PMID: 24247923 DOI: 10.1093/ehjci/jet243] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Carotid contrast-enhanced ultrasound (CEUS) was recently proposed for the evaluation of large-vessel vasculitides (LVV), particularly to assess vascularization within the vessel wall. The aim of this pilot study was to evaluate the potential of carotid colour Doppler ultrasound (CDUS) and CEUS in patients with LVV. METHODS AND RESULTS This prospective study included seven patients (mean age 48 ± 14 years, all females) with established LVV (Takayasu arteritis or giant cell arteritis). All patients underwent CDUS and CEUS (14 carotid arteries). Intima-media thickness, lumen diameter, Doppler velocities, vessel wall thickening, and lesion thickness were assessed. CEUS was used to improve visualization of the lumen-to-vessel wall border, and to visualize carotid wall vascularization. Four (57%) patients [7 (50%) carotid arteries] exhibited lesions, and the average lesion thickness was 2.0 ± 0.5 mm. According to the Doppler peak systolic velocity, 5 (35%) carotid arteries had a <50% stenosis, 1 (7%) had a 50-70% stenosis, and 1 (7%) had a ≥70% stenosis. The contrast agent improved the image quality and the definition of the lumen-to-vascular wall border. Carotid wall vascularization was observed in 5 (71%) patients [9 (64%) carotid arteries]. Five (36%) carotid arteries had mild-to-moderate vascularization, and 4 (29%) had severe wall vascularization. CONCLUSION Carotid CDUS allows the assessment of anatomical features of LVV, including vessel wall thickening and degree of stenosis. Carotid CEUS improves the visualization of the lumen border, and allows dynamic assessment of carotid wall vascularization, which is a potential marker of disease activity in patients with LVV.
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Affiliation(s)
- Arend F L Schinkel
- Department of Cardiology, Room Ba304, Thoraxcenter, Erasmus MC, 's-Gravendijkwal 230, Rotterdam 3015 CE Rotterdam, The Netherlands
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van den Oord SCH, Akkus Z, Roeters van Lennep JE, Bosch JG, van der Steen AFW, Sijbrands EJG, Schinkel AFL. Assessment of subclinical atherosclerosis and intraplaque neovascularization using quantitative contrast-enhanced ultrasound in patients with familial hypercholesterolemia. Atherosclerosis 2013; 231:107-13. [PMID: 24125419 DOI: 10.1016/j.atherosclerosis.2013.08.040] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 08/28/2013] [Accepted: 08/28/2013] [Indexed: 11/24/2022]
Abstract
OBJECTIVE Patients with heterozygous familial hypercholesterolemia (FH) are at severely increased risk of developing atherosclerosis at relatively young age. The aim of this study was to assess the prevalence of subclinical atherosclerosis and intraplaque neovascularization (IPN) in patients with FH, using contrast-enhanced ultrasound (CEUS) of the carotid arteries. METHODS The study population consisted of 69 consecutive asymptomatic patients with FH (48% women, mean age 55 ± 8 years). All patients underwent carotid ultrasound to evaluate the presence and severity of carotid atherosclerosis, and CEUS to assess IPN. IPN was assessed in near wall plaques using a semi-quantitative grading scale and semi-automated quantification software. RESULTS Carotid plaque was present in 62 patients (90%). A total of 49 patients had plaques that were eligible for the assessment of IPN: 7 patients (14%) had no IPN, 39 (80%) had mild to moderate IPN and 3 (6%) had severe IPN. Semi-automated quantification software showed no statistical significant difference in the amount of IPN between patients > 50 years and patients ≤ 50 years and between patients with a defective low-density lipoprotein receptor (LDLR) mutation and patients with a negative LDLR mutation. Plaques with irregular or ulcerated surface had significantly more IPN than plaques with a smooth surface (p < 0.05). CONCLUSION Carotid ultrasound demonstrated atherosclerotic plaque in 90% of asymptomatic patients with FH without known atherosclerosis. IPN assessed with CEUS, was present in 86% of these patients. Irregular and ulcerated plaques exhibited significantly more IPN than plaques with a smooth surface.
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Affiliation(s)
- Stijn C H van den Oord
- Dept. of Cardiology, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands; Dept. of Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands
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Pseudo-enhancement does not explain the increased carotid adventitial vasa vasorum signal in diabetic patients. Atherosclerosis 2013; 229:459-61. [DOI: 10.1016/j.atherosclerosis.2013.06.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Accepted: 06/13/2013] [Indexed: 11/18/2022]
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Hjelmgren O, Holdfeldt P, Johansson L, Fagerberg B, Prahl U, Schmidt C, Bergström G. Identification of Vascularised Carotid Plaques Using a Standardised and Reproducible Technique to Measure Ultrasound Contrast Uptake. Eur J Vasc Endovasc Surg 2013; 46:21-8. [DOI: 10.1016/j.ejvs.2013.03.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Accepted: 03/26/2013] [Indexed: 01/06/2023]
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van den Oord SCH, Renaud G, Bosch JG, de Jong N, van der Steen AFW, Schinkel AFL. Far wall pseudo-enhancement: a neglected artifact in carotid contrast-enhanced ultrasound? Atherosclerosis 2013; 229:451-2. [PMID: 23880203 DOI: 10.1016/j.atherosclerosis.2013.04.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 04/12/2013] [Accepted: 04/23/2013] [Indexed: 12/22/2022]
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Renaud G, Bosch JG, Ten Kate GL, Shamdasani V, Entrekin R, de Jong N, van der Steen AFW. Counter-propagating wave interaction for contrast-enhanced ultrasound imaging. Phys Med Biol 2012; 57:L9-18. [PMID: 23047302 DOI: 10.1088/0031-9155/57/21/l9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Most techniques for contrast-enhanced ultrasound imaging require linear propagation to detect nonlinear scattering of contrast agent microbubbles. Waveform distortion due to nonlinear propagation impairs their ability to distinguish microbubbles from tissue. As a result, tissue can be misclassified as microbubbles, and contrast agent concentration can be overestimated; therefore, these artifacts can significantly impair the quality of medical diagnoses. Contrary to biological tissue, lipid-coated gas microbubbles used as a contrast agent allow the interaction of two acoustic waves propagating in opposite directions (counter-propagation). Based on that principle, we describe a strategy to detect microbubbles that is free from nonlinear propagation artifacts. In vitro images were acquired with an ultrasound scanner in a phantom of tissue-mimicking material with a cavity containing a contrast agent. Unlike the default mode of the scanner using amplitude modulation to detect microbubbles, the pulse sequence exploiting counter-propagating wave interaction creates no pseudoenhancement behind the cavity in the contrast image.
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Affiliation(s)
- G Renaud
- Biomedical Engineering, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands.
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