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Campo I, Granata A, Derchi LE, Piccoli G, Cassetti P, Cova MA, Bertolotto M. Tips and tricks for a correct interpretation of contrast-enhanced ultrasound. LA RADIOLOGIA MEDICA 2024; 129:536-548. [PMID: 38512611 DOI: 10.1007/s11547-024-01784-0] [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: 09/04/2023] [Accepted: 01/10/2024] [Indexed: 03/23/2024]
Abstract
Although contrast-enhanced ultrasound (CEUS) is a widespread and easily manageable technique, image interpretation errors can occur due to the operator's inexperience and/or lack of knowledge of the frequent pitfalls, which may cause uncertain diagnosis and misdiagnosis. Indeed, knowledge of the basic physical and technical principles of ultrasound is needed both to understand sonographic image findings and to evaluate the potential and limits of the method. Like the B-mode ultrasound, the quality of the CEUS examination is also subject not only to the adequate manual skill of the operator but also to his/her deep knowledge of the technique which improves the quality of the image helping avoid misleading artifacts. In this review, the main parameters influencing a CEUS examination will be described by taking into account the most common errors and pitfalls and their possible solutions.
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Affiliation(s)
- Irene Campo
- Department of Radiology, University of Trieste, Ospedale San Giovanni di Dio, Via Fatebenefratelli, 34, 34170, Gorizia, Italy.
| | - Antonio Granata
- Nephrology and Dialysis Unit, Ospedale Cannizzaro in via Messina, 829, 95126, Catania, CT, Italy
| | - Lorenzo E Derchi
- Radiology Section, Department of Health Sciences (DISSAL), University of Genoa, Via A. Pastore 1, 16132, Genoa, Italy
| | | | - Paolo Cassetti
- Department of Radiology, University of Trieste, Ospedale San Giovanni di Dio, Via Fatebenefratelli, 34, 34170, Gorizia, Italy
| | - Maria Assunta Cova
- Department of Radiology, University of Trieste, Ospedale San Giovanni di Dio, Via Fatebenefratelli, 34, 34170, Gorizia, Italy
- Department of Radiology, University of Trieste, Ospedale di Cattinara, Strada di Fiume 447, 34149, Trieste, Italy
| | - Michele Bertolotto
- Department of Radiology, University of Trieste, Ospedale San Giovanni di Dio, Via Fatebenefratelli, 34, 34170, Gorizia, Italy
- Department of Radiology, University of Trieste, Ospedale di Cattinara, Strada di Fiume 447, 34149, Trieste, Italy
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2
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Elbanna KY, Krishna S, Finelli A, Atri M. Contrast-Enhanced Ultrasound of the Indeterminate Renal Mass, From the AJR "How We Do It" Special Series. AJR Am J Roentgenol 2024. [PMID: 38415576 DOI: 10.2214/ajr.24.30817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
Contrast-enhanced ultrasound (CEUS) is distinguished from CT and MRI by the use of microbubble ultrasound contrast agents (UCAs) with intravascular blood pool distribution. When performing CEUS, low-intensity ultrasound allows real-time tissue subtraction imaging, whereas high-intensity ultrasound leads to microbubble destruction, enabling visualization of the contrast inflow pattern. CEUS has exceptional contrast resolution that enables the detection of even minimal blood flow, achieving very high NPV for ruling out vascular perfusion and providing high frame rates in the evaluation of tissue perfusion dynamics. UCAs undergo hepatic metabolism and pulmonary clearance, ensuring safety in patients with renal impairment. CEUS excels in distinguishing solid from cystic renal masses, with higher sensitivity than CT or MRI for detection of lesion enhancement. CEUS can aid the further characterization of both solid and cystic lesions and may have particular applications in the surveillance of cystic masses and surveillance after renal cell carcinoma ablation. This review describes the use of CEUS to help characterize indeterminate renal masses, based on the authors' institutional experience. The article highlights key differences between CEUS and CT or MRI, and provides practical insights for performing and interpreting CEUS of renal masses.
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Affiliation(s)
- Khaled Y Elbanna
- Department of Medical Imaging, University Medical Imaging Toronto, University of Toronto, Canada
| | - Satheesh Krishna
- Department of Medical Imaging, University Medical Imaging Toronto, University of Toronto, Canada
| | - Antonio Finelli
- Division of Urology, Departments of Surgery and of Surgical Oncology, Princess Margaret Hospital and the University Health Network, University of Toronto, Canada
| | - Mostafa Atri
- Department of Medical Imaging, University Medical Imaging Toronto, University of Toronto, Canada
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3
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Fetzer DT, Vijay K, Caserta MP, Patterson-Lachowicz A, Dahiya N, Rodgers SK. Artifacts and Technical Considerations at Contrast-enhanced US. Radiographics 2023; 43:e220093. [PMID: 36563094 DOI: 10.1148/rg.220093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Contrast-enhanced US (CEUS), similar to other radiologic modalities, requires specific technical considerations and is subject to image artifacts. These artifacts may affect examination quality, negatively impact diagnostic accuracy, and decrease user comfort when using this emerging technique. Some artifacts are related to commonly known gray-scale US artifacts that can also appear on the contrast-only image (tissue-subtracted image obtained with the linear responses from background tissues nulled). These may include acoustic shadowing and enhancement; reverberation, refraction, and reflection; and poor penetration. Other artifacts are exclusive to CEUS owing to the techniques used for contrast mode image generation and the unique properties of the microbubbles that constitute ultrasound-specific contrast agents (UCAs). UCA-related artifacts may appear on the contrast-only image, the gray-scale image, or various Doppler mode images. Artifacts related to CEUS may include nonlinear artifacts and unintentional microbubble destruction resulting in pseudowashout. The microbubbles themselves may result in specific artifacts such as pseudoenhancement, signal saturation, and attenuation and shadowing and can confound the use of color and spectral Doppler US. Identifying and understanding these artifacts and knowing how to mitigate them may improve the quality of the imaging study, increase user confidence, and improve patient care. The authors review the principles of UCAs and the sound-microbubble interaction, as well as the technical aspects of image generation. Technical considerations, including patient positioning, depth, acoustic window, and contrast agent dose, also are discussed. Specific artifacts are described, with tips on how to identify and, if necessary, apply corrective measures, with the goal of improving examination quality. © RSNA, 2022 Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.
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Affiliation(s)
- David T Fetzer
- From the Department of Radiology, UT Southwestern Medical Center, 5323 Harry Hines Blvd, E6-230-BF, Dallas, TX 75390-8896 (D.T.F., K.V., A.P.L.); Department of Radiology, Mayo Clinic, Jacksonville, FL (M.P.C.); Department of Radiology, Mayo Clinic, Phoenix, AZ (N.D.); and Department of Radiology, Jefferson Health New Jersey, Thomas Jefferson University, Cherry Hill, NJ (S.K.R.)
| | - Kanupriya Vijay
- From the Department of Radiology, UT Southwestern Medical Center, 5323 Harry Hines Blvd, E6-230-BF, Dallas, TX 75390-8896 (D.T.F., K.V., A.P.L.); Department of Radiology, Mayo Clinic, Jacksonville, FL (M.P.C.); Department of Radiology, Mayo Clinic, Phoenix, AZ (N.D.); and Department of Radiology, Jefferson Health New Jersey, Thomas Jefferson University, Cherry Hill, NJ (S.K.R.)
| | - Melanie P Caserta
- From the Department of Radiology, UT Southwestern Medical Center, 5323 Harry Hines Blvd, E6-230-BF, Dallas, TX 75390-8896 (D.T.F., K.V., A.P.L.); Department of Radiology, Mayo Clinic, Jacksonville, FL (M.P.C.); Department of Radiology, Mayo Clinic, Phoenix, AZ (N.D.); and Department of Radiology, Jefferson Health New Jersey, Thomas Jefferson University, Cherry Hill, NJ (S.K.R.)
| | - Amber Patterson-Lachowicz
- From the Department of Radiology, UT Southwestern Medical Center, 5323 Harry Hines Blvd, E6-230-BF, Dallas, TX 75390-8896 (D.T.F., K.V., A.P.L.); Department of Radiology, Mayo Clinic, Jacksonville, FL (M.P.C.); Department of Radiology, Mayo Clinic, Phoenix, AZ (N.D.); and Department of Radiology, Jefferson Health New Jersey, Thomas Jefferson University, Cherry Hill, NJ (S.K.R.)
| | - Nirvikar Dahiya
- From the Department of Radiology, UT Southwestern Medical Center, 5323 Harry Hines Blvd, E6-230-BF, Dallas, TX 75390-8896 (D.T.F., K.V., A.P.L.); Department of Radiology, Mayo Clinic, Jacksonville, FL (M.P.C.); Department of Radiology, Mayo Clinic, Phoenix, AZ (N.D.); and Department of Radiology, Jefferson Health New Jersey, Thomas Jefferson University, Cherry Hill, NJ (S.K.R.)
| | - Shuchi K Rodgers
- From the Department of Radiology, UT Southwestern Medical Center, 5323 Harry Hines Blvd, E6-230-BF, Dallas, TX 75390-8896 (D.T.F., K.V., A.P.L.); Department of Radiology, Mayo Clinic, Jacksonville, FL (M.P.C.); Department of Radiology, Mayo Clinic, Phoenix, AZ (N.D.); and Department of Radiology, Jefferson Health New Jersey, Thomas Jefferson University, Cherry Hill, NJ (S.K.R.)
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Atri M, Jang HJ, Kim TK, Khalili K. Contrast-enhanced US of the Liver and Kidney: A Problem-solving Modality. Radiology 2022; 303:11-25. [PMID: 35191740 DOI: 10.1148/radiol.211347] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Contrast-enhanced US (CEUS) has an important role as a supplement to CT or MRI in clinical practice. The main established utilizations are in the liver and the kidney. The primary advantages of CEUS compared with contrast-enhanced CT or MRI relate to its superior contrast resolution, real-time continuous scanning, pure intravascular nature, portability, and safety-especially in patients with renal impairment or CT or MRI contrast agent allergy. This article focuses on the use of CEUS in the liver and kidney.
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Affiliation(s)
- Mostafa Atri
- From the Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital, Women's College Hospital, University of Toronto, Toronto General Hospital, 585 University Ave, Toronto, ON, Canada M5G 2N2
| | - Hyun-Jung Jang
- From the Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital, Women's College Hospital, University of Toronto, Toronto General Hospital, 585 University Ave, Toronto, ON, Canada M5G 2N2
| | - Tae Kyoung Kim
- From the Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital, Women's College Hospital, University of Toronto, Toronto General Hospital, 585 University Ave, Toronto, ON, Canada M5G 2N2
| | - Korosh Khalili
- From the Joint Department of Medical Imaging, University Health Network, Mount Sinai Hospital, Women's College Hospital, University of Toronto, Toronto General Hospital, 585 University Ave, Toronto, ON, Canada M5G 2N2
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5
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Burns PN. Imaging Microbubbles in Children: A Light Foot on the Gas. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2021; 40:2535-2536. [PMID: 33599310 DOI: 10.1002/jum.15656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 01/17/2021] [Indexed: 06/12/2023]
Affiliation(s)
- Peter N Burns
- University of Toronto - Medical Biophysics, Sunnybrook Health Science Centre, Toronto, Ontario, Canada
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6
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Meloni MF, Francica G, Chiang J, Coltorti A, Danzi R, Laeseke PF. Use of Contrast-Enhanced Ultrasound in Ablation Therapy of HCC: Planning, Guiding, and Assessing Treatment Response. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2021; 40:879-894. [PMID: 32936485 DOI: 10.1002/jum.15471] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 07/23/2020] [Indexed: 06/11/2023]
Abstract
Contrast-enhanced ultrasonography (CEUS) plays an important role in the management of patients treated with ablation therapies, in the diagnostic, therapeutic and monitoring phases. Compared to contrast-enhanced computed tomography and contrast-enhanced magnetic resonance imaging, CEUS presents several advantages in imaging HCC, including real time imaging capability, high sensitivity for tumor vascularity, absence of renal toxicity, no ionizing radiation, repeatability of injections, good compliance by the patient and low cost. The purpose of this review is to evaluate the role of CEUS in the management of the patients with HCC treated with ablation therapies and describe how in our protocol CEUS is integrated with the other imaging modalities such as contrast-enhanced computed tomography and contrast-enhanced magnetic resonance imaging.
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Affiliation(s)
- Maria Franca Meloni
- Radiology Department, University of Pavia, Italy and Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA
| | - Giampiero Francica
- Interventional Ultrasound Unit, Pineta Grande Hospital, Castel Volturno, Italy
| | - Jason Chiang
- Department of Radiology, Ronald Reagan UCLA Medical Center, Los Angeles, USA
| | - Andrea Coltorti
- Department of Radiology, Federico II University, Naples, Italy
| | - Roberta Danzi
- Department of Radiology, Pineta Grande Hospital, Castel Volturno, Italy
| | - Paul F Laeseke
- Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA
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7
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Characterization of Indeterminate Liver Lesions on CT and MRI With Contrast-Enhanced Ultrasound: What Is the Evidence? AJR Am J Roentgenol 2020; 214:1295-1304. [DOI: 10.2214/ajr.19.21498] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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8
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Wilson SR, Burns PN, Kono Y. Contrast-Enhanced Ultrasound of Focal Liver Masses: A Success Story. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:1059-1070. [PMID: 32059917 DOI: 10.1016/j.ultrasmedbio.2019.12.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 12/17/2019] [Accepted: 12/19/2019] [Indexed: 06/10/2023]
Abstract
The epidemic of increasing fatty liver disease and liver cancer worldwide, and especially in Western society, has given new importance to non-invasive liver imaging. Contrast-enhanced ultrasound (CEUS) using microbubble contrast agents provides unique advantages over computed tomography (CT) and magnetic resonance imaging (MRI), the currently established methods. CEUS provides determination of malignancy and allows excellent differential diagnosis of a focal liver mass, based on arterial phase enhancement patterns and assessment of the timing and intensity of washout. Today, increased use of CEUS has provided safe and rapid diagnosis of incidentally detected liver masses, improved multidisciplinary management of nodules in a cirrhotic liver, facilitated ablative therapy for liver tumors and allowed diagnosis of hepatocellular carcinoma without biopsy. Benefits of CEUS include the dynamic real-time depiction of tumor perfusion and the fact that it is a purely intravascular agent, accurately reflecting tumoral and inflammatory blood flow. CEUS has many similarities to contrast-enhanced CT and MRI but also unique differences, which are described. The integration of CEUS into a multimodality imaging setting optimizes patient care.
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Affiliation(s)
- Stephanie R Wilson
- Department of Radiology, and Division of Gastroenterology, Department of Medicine, University of Calgary, Foothills Medical Centre, Calgary, Alberta, Canada.
| | - Peter N Burns
- Department of Medical Biophysics, University of Toronto, Imaging Research, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Yuko Kono
- Department of Medicine, Division of Gastroenterology and Hepatology, University of California San Diego, San Diego, CA
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9
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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: 72] [Impact Index Per Article: 18.0] [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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10
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Rodgers SK. Invited Commentary on "Contrast-enhanced US in Local Ablative Therapy and Secondary Surveillance for Hepatocellular Carcinoma," with Author Response. Radiographics 2019; 39:1322-1324. [PMID: 31364947 DOI: 10.1148/rg.2019190049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Shuchi K Rodgers
- Department of Radiology, Einstein Medical Center Philadelphia, Pennsylvania
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11
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Bansal S, Gui J, Merrill C, Wong JK, Burak KW, Wilson SR. Contrast-enhanced US in Local Ablative Therapy and Secondary Surveillance for Hepatocellular Carcinoma. Radiographics 2019; 39:1302-1322. [PMID: 31348734 DOI: 10.1148/rg.2019180205] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Hepatocellular carcinoma (HCC) has a high incidence of recurrence following therapy. Therefore, secondary surveillance (scheduled follow-up imaging after treatment) is an important part of disease management. The recent approval in the United States for use of a microbubble-based contrast agent for US liver imaging promotes the increased use of contrast-enhanced US (CEUS) in patients with HCC. Although the criteria for the diagnosis of HCC at CEUS are well described, there is a paucity of published literature describing the role of CEUS in ablative therapy and secondary surveillance. In the setting of ablative therapy, CEUS can have vital roles, including patient selection, intraprocedural guidance, and immediate postprocedural assessment. Although CEUS is not widely used, the authors found that it can be used to accurately detect residual or recurrent tumor, characterize the geographic pattern of recurrence (intrazonal, extrazonal, segmental, or remote), and assess for tumor in vein. In addition, similar to primary surveillance, secondary surveillance includes assessment of the entire liver for evaluation of new nodules. Arterial phase hyperenhancement is the reference standard characteristic of disease recurrence at secondary surveillance with CEUS. ©RSNA, 2019 See discussion on this article by Rodgers.
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Affiliation(s)
- Sanjay Bansal
- From the Department of Diagnostic Imaging, Foothills Medical Centre, 1403 29 St NW, Calgary, AB, Canada T2N 2T9 (S.B., J.G., C.M., J.K.W., S.R.W.); and Departments of Medicine, Division of Gastroenterology and Hepatology (K.W.B., S.R.W.), and Radiology (J.K.W., S.R.W.), University of Calgary, Calgary, Alberta, Canada
| | - Jonathan Gui
- From the Department of Diagnostic Imaging, Foothills Medical Centre, 1403 29 St NW, Calgary, AB, Canada T2N 2T9 (S.B., J.G., C.M., J.K.W., S.R.W.); and Departments of Medicine, Division of Gastroenterology and Hepatology (K.W.B., S.R.W.), and Radiology (J.K.W., S.R.W.), University of Calgary, Calgary, Alberta, Canada
| | - Christina Merrill
- From the Department of Diagnostic Imaging, Foothills Medical Centre, 1403 29 St NW, Calgary, AB, Canada T2N 2T9 (S.B., J.G., C.M., J.K.W., S.R.W.); and Departments of Medicine, Division of Gastroenterology and Hepatology (K.W.B., S.R.W.), and Radiology (J.K.W., S.R.W.), University of Calgary, Calgary, Alberta, Canada
| | - Jason K Wong
- From the Department of Diagnostic Imaging, Foothills Medical Centre, 1403 29 St NW, Calgary, AB, Canada T2N 2T9 (S.B., J.G., C.M., J.K.W., S.R.W.); and Departments of Medicine, Division of Gastroenterology and Hepatology (K.W.B., S.R.W.), and Radiology (J.K.W., S.R.W.), University of Calgary, Calgary, Alberta, Canada
| | - Kelly W Burak
- From the Department of Diagnostic Imaging, Foothills Medical Centre, 1403 29 St NW, Calgary, AB, Canada T2N 2T9 (S.B., J.G., C.M., J.K.W., S.R.W.); and Departments of Medicine, Division of Gastroenterology and Hepatology (K.W.B., S.R.W.), and Radiology (J.K.W., S.R.W.), University of Calgary, Calgary, Alberta, Canada
| | - Stephanie R Wilson
- From the Department of Diagnostic Imaging, Foothills Medical Centre, 1403 29 St NW, Calgary, AB, Canada T2N 2T9 (S.B., J.G., C.M., J.K.W., S.R.W.); and Departments of Medicine, Division of Gastroenterology and Hepatology (K.W.B., S.R.W.), and Radiology (J.K.W., S.R.W.), University of Calgary, Calgary, Alberta, Canada
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12
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Navin PJ, Venkatesh SK. Hepatocellular Carcinoma: State of the Art Imaging and Recent Advances. J Clin Transl Hepatol 2019; 7:72-85. [PMID: 30944823 PMCID: PMC6441649 DOI: 10.14218/jcth.2018.00032] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 12/31/2018] [Accepted: 01/04/2019] [Indexed: 02/07/2023] Open
Abstract
The incidence of hepatocellular carcinoma (HCC) is increasing, with this trend expected to continue to the year 2030. Hepatocarcinogenesis follows a predictable course, which makes adequate identification and surveillance of at-risk individuals central to a successful outcome. Moreover, imaging is central to this surveillance, and ultimately to diagnosis and management. Many liver study groups throughout Asia, North America and Europe advocate a surveillance program for at-risk individuals to allow early identification of HCC. Ultrasound is the most commonly utilized imaging modality. Many societies offer guidelines on how to diagnose HCC. The Liver Image Reporting and Data System (LIRADS) was introduced to standardize the acquisition, interpretation, reporting and data collection of HCC cases. The LIRADS advocates diagnosis using multiphase computed tomography or magnetic resonance imaging (MRI) imaging. The 2017 version also introduces contrast-enhanced ultrasound as a novel approach to diagnosis. Indeed, imaging techniques have evolved to improve diagnostic accuracy and characterization of HCC lesions. Newer techniques, such as T1 mapping, intravoxel incoherent motion analysis and textural analysis, assess specific characteristics that may help grade the tumor and guide management, allowing for a more personalized approach to patient care. This review aims to analyze the utility of imaging in the surveillance and diagnosis of HCC and to assess novel techniques which may increase the accuracy of imaging and determine optimal treatment strategies.
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Affiliation(s)
| | - Sudhakar K. Venkatesh
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
- *Correspondence to: Sudhakar K. Venkatesh, Mayo Clinic, Rochester, 200 1 Street, Rochester MN 55905, USA. Tel: +1-507-284-1728, Fax: +1-507-284-2405, E-mail:
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13
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Wang C. Contrast‐enhanced ultrasound for hepatocellular carcinoma: Focusing on unique benefits and indications. ADVANCES IN DIGESTIVE MEDICINE 2019. [DOI: 10.1002/aid2.13111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Chia‐Chi Wang
- Department of GastroenterologyTaipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation Taipei Taiwan
- School of MedicineTzu Chi University Hualien Taiwan
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14
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Liu X, Jang HJ, Khalili K, Kim TK, Atri M. Successful Integration of Contrast-enhanced US into Routine Abdominal Imaging. Radiographics 2018; 38:1454-1477. [DOI: 10.1148/rg.2018170152] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Xiaoyang Liu
- From the Department of Medical Imaging, University of Toronto, University Health Network, Toronto General Hospital, 585 University Ave, Toronto, ON, Canada M5G 2N2
| | - Hyun-Jung Jang
- From the Department of Medical Imaging, University of Toronto, University Health Network, Toronto General Hospital, 585 University Ave, Toronto, ON, Canada M5G 2N2
| | - Korosh Khalili
- From the Department of Medical Imaging, University of Toronto, University Health Network, Toronto General Hospital, 585 University Ave, Toronto, ON, Canada M5G 2N2
| | - Tae Kyoung Kim
- From the Department of Medical Imaging, University of Toronto, University Health Network, Toronto General Hospital, 585 University Ave, Toronto, ON, Canada M5G 2N2
| | - Mostafa Atri
- From the Department of Medical Imaging, University of Toronto, University Health Network, Toronto General Hospital, 585 University Ave, Toronto, ON, Canada M5G 2N2
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15
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Contrast-enhanced ultrasound of the liver: technical and lexicon recommendations from the ACR CEUS LI-RADS working group. Abdom Radiol (NY) 2018; 43:861-879. [PMID: 29151131 DOI: 10.1007/s00261-017-1392-0] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Contrast-enhanced ultrasound (CEUS) is a specific form of ultrasound imaging performed with intravenous administration of microbubble contrast agents. It has been extensively used for liver tumor characterization and was recently added to the American College of Radiology Liver Imaging Reporting and Data System (CEUS LI-RADS). This paper describes technical recommendations for successful liver CEUS lesion characterization, and provides imaging protocol and Lexicon of imaging findings.
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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: 183] [Impact Index Per Article: 30.5] [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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Contrast-Enhanced Ultrasound of the Liver: Optimizing Technique and Clinical Applications. AJR Am J Roentgenol 2017; 210:320-332. [PMID: 29220210 DOI: 10.2214/ajr.17.17843] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
OBJECTIVE The purpose of this article is to review the general principles, technique, and clinical applications of contrast-enhanced ultrasound of the liver. CONCLUSION Proper technique and optimization of contrast-enhanced ultrasound require a balance between maintaining the integrity of the microbubble contrast agent and preserving the ultrasound signal. Established and emerging applications in the liver include diagnosis of focal lesions, aiding ultrasound-guided intervention, monitoring of therapy, and aiding surgical management.
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18
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Lindsey BD, Kim J, Dayton PA, Jiang X. Dual-Frequency Piezoelectric Endoscopic Transducer for Imaging Vascular Invasion in Pancreatic Cancer. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2017; 64:1078-1086. [PMID: 28489536 PMCID: PMC5568756 DOI: 10.1109/tuffc.2017.2702010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Cancers of the pancreas have the poorest prognosis among all cancers, as many tumors are not detected until surgery is no longer a viable option. Surgical viability is typically determined via endoscopic ultrasound imaging. However, many patients who may be eligible for resection are not offered surgery due to diagnostic challenges in determining vascular or lymphatic invasion. In this paper, we describe the development of a dual-frequency piezoelectric transducer for rotational endoscopic imaging designed to transmit at 4 MHz and receive at 20 MHz in order to image microbubble-specific superharmonic signals. Imaging performance is assessed in a tissue-mimicking phantom at depths from 1 cm [contrast-to-tissue ratio (CTR) = 21.6 dB] to 2.5 cm (CTR = 11.4 dB), in ex vivo porcine vessels, and in vivo in a rodent. The prototyped 1.1-mm aperture transducer demonstrates contrast-specific imaging of microbubbles in a 200- [Formula: see text]-diameter tube through the wall of a 1-cm-diameter porcine artery, suggesting such a device may enable direct visualization of small vessels from within the lumen of larger vessels such as the portal vein or superior mesenteric vein.
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Jo PC, Jang HJ, Burns PN, Burak KW, Kim TK, Wilson SR. Integration of Contrast-enhanced US into a Multimodality Approach to Imaging of Nodules in a Cirrhotic Liver: How I Do It. Radiology 2017; 282:317-331. [PMID: 28099108 DOI: 10.1148/radiol.2016151732] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Accurate characterization of cirrhotic nodules and early diagnosis of hepatocellular carcinoma (HCC) are of vital importance. Currently, computed tomography (CT) and magnetic resonance (MR) imaging are standard modalities for the investigation of new nodules found at surveillance ultrasonography (US). This article describes the successful integration of contrast material-enhanced US into a multimodality approach for diagnosis of HCC and its benefits in this population. The application of contrast-enhanced US immediately following surveillance US allows for prompt dynamic contrast-enhanced evaluation, removing the need for further imaging of benign lesions. Contrast-enhanced US also provides dynamic real-time assessment of tumor vascularity so that contrast enhancement can be identified regardless of its timing or duration, allowing for detection of arterial hypervascularity and portal venous washout. The purely intravascular nature of US contrast agents is valuable as the rapid washout of nonhepatocyte malignancies is highly contributory to their differentiation from HCC. The authors believe contrast-enhanced US provides complementary information to CT and MR imaging in the characterization of nodules in high-risk patients. © RSNA, 2017 Online supplemental material is available for this article.
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Affiliation(s)
- Patricia C Jo
- From the Department of Radiology (P.C.J., S.R.W.) and Department of Medicine, Division of Gastroenterology (K.W.B., S.R.W.), Foothills Medical Centre, University of Calgary, 1403 29 St NW, Calgary, AB, Canada T2N 2T9; Department of Medical Imaging, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (H.J.J., T.K.K.); and Department of Imaging Research, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ont, Canada (P.N.B.)
| | - Hyun-Jung Jang
- From the Department of Radiology (P.C.J., S.R.W.) and Department of Medicine, Division of Gastroenterology (K.W.B., S.R.W.), Foothills Medical Centre, University of Calgary, 1403 29 St NW, Calgary, AB, Canada T2N 2T9; Department of Medical Imaging, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (H.J.J., T.K.K.); and Department of Imaging Research, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ont, Canada (P.N.B.)
| | - Peter N Burns
- From the Department of Radiology (P.C.J., S.R.W.) and Department of Medicine, Division of Gastroenterology (K.W.B., S.R.W.), Foothills Medical Centre, University of Calgary, 1403 29 St NW, Calgary, AB, Canada T2N 2T9; Department of Medical Imaging, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (H.J.J., T.K.K.); and Department of Imaging Research, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ont, Canada (P.N.B.)
| | - Kelly W Burak
- From the Department of Radiology (P.C.J., S.R.W.) and Department of Medicine, Division of Gastroenterology (K.W.B., S.R.W.), Foothills Medical Centre, University of Calgary, 1403 29 St NW, Calgary, AB, Canada T2N 2T9; Department of Medical Imaging, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (H.J.J., T.K.K.); and Department of Imaging Research, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ont, Canada (P.N.B.)
| | - Tae Kyoung Kim
- From the Department of Radiology (P.C.J., S.R.W.) and Department of Medicine, Division of Gastroenterology (K.W.B., S.R.W.), Foothills Medical Centre, University of Calgary, 1403 29 St NW, Calgary, AB, Canada T2N 2T9; Department of Medical Imaging, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (H.J.J., T.K.K.); and Department of Imaging Research, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ont, Canada (P.N.B.)
| | - Stephanie R Wilson
- From the Department of Radiology (P.C.J., S.R.W.) and Department of Medicine, Division of Gastroenterology (K.W.B., S.R.W.), Foothills Medical Centre, University of Calgary, 1403 29 St NW, Calgary, AB, Canada T2N 2T9; Department of Medical Imaging, Toronto General Hospital, University of Toronto, Toronto, Ont, Canada (H.J.J., T.K.K.); and Department of Imaging Research, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ont, Canada (P.N.B.)
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20
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Demi L, Van Sloun RJG, Wijkstra H, Mischi M. Towards Dynamic Contrast Specific Ultrasound Tomography. Sci Rep 2016; 6:34458. [PMID: 27703251 PMCID: PMC5050488 DOI: 10.1038/srep34458] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 09/13/2016] [Indexed: 11/09/2022] Open
Abstract
We report on the first study demonstrating the ability of a recently-developed, contrast-enhanced, ultrasound imaging method, referred to as cumulative phase delay imaging (CPDI), to image and quantify ultrasound contrast agent (UCA) kinetics. Unlike standard ultrasound tomography, which exploits changes in speed of sound and attenuation, CPDI is based on a marker specific to UCAs, thus enabling dynamic contrast-specific ultrasound tomography (DCS-UST). For breast imaging, DCS-UST will lead to a more practical, faster, and less operator-dependent imaging procedure compared to standard echo-contrast, while preserving accurate imaging of contrast kinetics. Moreover, a linear relation between CPD values and ultrasound second-harmonic intensity was measured (coefficient of determination = 0.87). DCS-UST can find clinical applications as a diagnostic method for breast cancer localization, adding important features to multi-parametric ultrasound tomography of the breast.
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Affiliation(s)
- Libertario Demi
- Biomedical Diagnostics Laboratory, Signal Processing Systems group, Faculty of Electrical Engineering, Eindhoven University of Technology, Eindhoven the Netherlands
| | - Ruud J G Van Sloun
- Biomedical Diagnostics Laboratory, Signal Processing Systems group, Faculty of Electrical Engineering, Eindhoven University of Technology, Eindhoven the Netherlands
| | - Hessel Wijkstra
- Biomedical Diagnostics Laboratory, Signal Processing Systems group, Faculty of Electrical Engineering, Eindhoven University of Technology, Eindhoven the Netherlands.,Academic Medical Center Amsterdam, Amsterdam, the Netherlands
| | - Massimo Mischi
- Biomedical Diagnostics Laboratory, Signal Processing Systems group, Faculty of Electrical Engineering, Eindhoven University of Technology, Eindhoven the Netherlands
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21
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Lekht I, Gulati M, Nayyar M, Katz MD, Ter-Oganesyan R, Marx M, Cen SY, Grant E. Role of contrast-enhanced ultrasound (CEUS) in evaluation of thermal ablation zone. Abdom Radiol (NY) 2016; 41:1511-21. [PMID: 26969495 DOI: 10.1007/s00261-016-0700-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
PURPOSE Thermal ablation has emerged as a mainstay therapy for primary and metastatic liver malignancy. Percutaneous thermal ablation is usually performed under CT and/or ultrasound guidance. CT guidance frequently utilizes iodinated contrast for tumor targeting, with additional radiation and contrast required at the end of the procedure to ensure satisfactory ablation margins. Contrast-enhanced ultrasound (CEUS) is an imaging technique utilizing microbubble contrast agents to demonstrate blood flow and tissue perfusion. In this study, we performed a retrospective review to assess the utility of CEUS in the immediate post ablation detection of residual tumor. METHODS Sixty-four ablations were retrospectively reviewed. 6/64 ablations (9.4%) had residual tumor on the first follow-up imaging after thermal ablation. There were two groups of patients. Group 1 underwent standard protocol thermal ablation with CT and/or ultrasound guidance. Group 2 not only had thermal ablation with a protocol identical to group 1, but also had CEUS assessment at the conclusion of the procedure to ensure satisfactory ablation zone. RESULTS The residual tumor rate in group 1 was 16.7% and the residual tumor rate in group 2 was 0%. The difference between the groups was statistically significant with a p value of 0.023. The results suggest that using CEUS assessment immediately after the ablation procedure reduces the rate of residual tumor after thermal ablation. CONCLUSION CEUS evaluation at the end of an ablation procedure is a powerful technique providing critical information to the treating interventional radiologist, without additional nephrotoxic contrast or ionizing radiation.
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Affiliation(s)
- Ilya Lekht
- Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo Street, Second Floor Imaging, Los Angeles, CA, 90033, USA
| | - Mittul Gulati
- Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo Street, Second Floor Imaging, Los Angeles, CA, 90033, USA
| | - Megha Nayyar
- Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo Street, Second Floor Imaging, Los Angeles, CA, 90033, USA.
| | - Michael D Katz
- Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo Street, Second Floor Imaging, Los Angeles, CA, 90033, USA
| | - Ramon Ter-Oganesyan
- Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo Street, Second Floor Imaging, Los Angeles, CA, 90033, USA
| | - Mary Marx
- Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo Street, Second Floor Imaging, Los Angeles, CA, 90033, USA
| | - Steven Y Cen
- Department of Radiology, Keck School of Medicine, University of Southern California, 2001 North Soto Street, Soto Building 210B, Los Angeles, 90089, USA
| | - Edward Grant
- Department of Radiology, Keck School of Medicine, University of Southern California, 1500 San Pablo Street, Second Floor Imaging, Los Angeles, CA, 90033, USA
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22
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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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23
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Kim TK, Khalili K, Jang HJ. Local ablation therapy with contrast-enhanced ultrasonography for hepatocellular carcinoma: a practical review. Ultrasonography 2015; 34:235-45. [PMID: 26169081 PMCID: PMC4603202 DOI: 10.14366/usg.15018] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 06/23/2015] [Accepted: 06/24/2015] [Indexed: 12/14/2022] Open
Abstract
A successful program for local ablation therapy for hepatocellular carcinoma (HCC) requires extensive imaging support for diagnosis and localization of HCC, imaging guidance for the ablation procedures, and post-treatment monitoring. Contrast-enhanced ultrasonography (CEUS) has several advantages over computed tomography/magnetic resonance imaging (CT/MRI), including real-time imaging capability, sensitive detection of arterial-phase hypervascularity and washout, no renal excretion, no ionizing radiation, repeatability, excellent patient compliance, and relatively low cost. CEUS is useful for image guidance for isoechoic lesions. While contrast-enhanced CT/MRI is the standard method for the diagnosis of HCC and post-ablation monitoring, CEUS is useful when CT/MRI findings are indeterminate or CT/MRI is contraindicated. This article provides a practical review of the role of CEUS in imaging algorithms for pre- and post-ablation therapy for HCC.
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Affiliation(s)
- Tae Kyoung Kim
- Department of Medical Imaging, Toronto General Hospital, University of Toronto, Toronto, ON, Canada
| | - Korosh Khalili
- Department of Medical Imaging, Toronto General Hospital, University of Toronto, Toronto, ON, Canada
| | - Hyun-Jung Jang
- Department of Medical Imaging, Toronto General Hospital, University of Toronto, Toronto, ON, Canada
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24
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Diana A, Linta N, Cipone M, Fedone V, Steiner JM, Fracassi F, Grandis A, Baron Toaldo M. Contrast-enhanced ultrasonography of the pancreas in healthy cats. BMC Vet Res 2015; 11:64. [PMID: 25879918 PMCID: PMC4367928 DOI: 10.1186/s12917-015-0380-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 02/27/2015] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND This study describes the pattern of ultrasonographic contrast enhancement of the pancreatic body and left lobe using a second-generation commercial contrast medium (Sonovue) in 10 clinically healthy cats. RESULTS Following contrast medium administration, microbubbles were observed within the splenic artery. This was followed by an inflow of contrast medium into the pancreatic capillary beds, providing a uniformly contrast-enhanced pancreas at peak intensity (PI). At the time of PI, a replenishment of the splenic and portal veins started and increased progressively during the wash-out phase. During the wash-out phase, the echogenicity of the pancreatic parenchyma decreased progressively. Perfusion parameters included arrival time (4.69 ± 1.26 s), time to peak from injection (7.52 ± 1.88 s), time to peak from initial rise (2.84 ± 0.88 s), peak intensity (6.58 ± 2.66 a.u.), and wash-in rate (2.11 ± 1.79 a.u./s). CONCLUSIONS This perfusion pattern of normal pancreatic parenchyma may be useful for characterising cats with exocrine pancreatic disorders.
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Affiliation(s)
- Alessia Diana
- Department of Veterinary Medical Sciences, Alma Mater Studiorum - University of Bologna, Via Tolara di Sopra 50, I-40064, Ozzano Emilia, Bologna, Italy.
| | - Nikolina Linta
- Department of Veterinary Medical Sciences, Alma Mater Studiorum - University of Bologna, Via Tolara di Sopra 50, I-40064, Ozzano Emilia, Bologna, Italy.
| | - Mario Cipone
- Department of Veterinary Medical Sciences, Alma Mater Studiorum - University of Bologna, Via Tolara di Sopra 50, I-40064, Ozzano Emilia, Bologna, Italy.
| | | | - Joerg M Steiner
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA.
| | - Federico Fracassi
- Department of Veterinary Medical Sciences, Alma Mater Studiorum - University of Bologna, Via Tolara di Sopra 50, I-40064, Ozzano Emilia, Bologna, Italy.
| | - Annamaria Grandis
- Department of Veterinary Medical Sciences, Alma Mater Studiorum - University of Bologna, Via Tolara di Sopra 50, I-40064, Ozzano Emilia, Bologna, Italy.
| | - Marco Baron Toaldo
- Department of Veterinary Medical Sciences, Alma Mater Studiorum - University of Bologna, Via Tolara di Sopra 50, I-40064, Ozzano Emilia, Bologna, Italy.
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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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26
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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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Alzaraa A, Gravante G, Chung WY, Al-Leswas D, Morgan B, Dennison A, Lloyd D. Contrast-enhanced ultrasound in the preoperative, intraoperative and postoperative assessment of liver lesions. Hepatol Res 2013; 43:809-19. [PMID: 23745715 DOI: 10.1111/hepr.12044] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2012] [Revised: 12/04/2012] [Accepted: 12/10/2012] [Indexed: 12/12/2022]
Abstract
The use of contrast agents (CA) with liver ultrasound (US) has gained recently an established role for the diagnosis of various hepatic diseases due to their safety, high versatility and low costs (contrast-enhanced ultrasound: CEUS). The purpose of this review is to provide a state-of-the-art summary of the available evidence for their use in the characterization of focal liver lesions. A published work search was conducted for all preclinical and clinical studies involving CA on hepatic US imaging. CEUS increases the sensitivity for lesion detection and the specificity to differentiate between benign and malignant diseases due to the enhanced visualization of the tumor microcirculation. Results achieved seem at least equivalent to those of spiral computed tomography or magnetic resonance imaging. The association of CA with intraoperative ultrasound has changed the surgical approach in 25% of patients and guarantees complete ablations by a single session in most of them. CEUS provides detailed information about tumor vasculature, improves the preoperative characterization and therefore the therapeutic strategy, and can evaluate the intraoperative completeness of the ablation.
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Affiliation(s)
- Ahmed Alzaraa
- Department of General Surgery, William Harvey Hospital, Ashford
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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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Abstract
The administration of a contrast agent is considered an essential tool to evaluate abdominal diseases using Ultrasound. The most targeted organ is the liver, especially to characterize focal liver lesions and to assess the response to percutaneous treatment. However, the expanding abdominal indications of contrast-enhanced ultrasound make this technique an important tool in the assessment of organ perfusion including the evaluation of ischemic, traumatic, and inflammatory diseases.
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Affiliation(s)
- Carlos Nicolau
- Radiology Department, Hospital Clínic, University of Barcelona, Spain.
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ten Kate GL, Renaud GGJ, Akkus Z, van den Oord SCH, ten Cate FJ, Shamdasani V, Entrekin RR, Sijbrands EJG, de Jong N, Bosch JG, Schinkel AFL, van der Steen AFW. Far-wall pseudoenhancement during contrast-enhanced ultrasound of the carotid arteries: clinical description and in vitro reproduction. ULTRASOUND IN MEDICINE & BIOLOGY 2012; 38:593-600. [PMID: 22341054 DOI: 10.1016/j.ultrasmedbio.2011.12.019] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 11/02/2011] [Accepted: 12/19/2011] [Indexed: 05/31/2023]
Abstract
The present study describes the presence of pseudoenhancement during contrast-enhanced ultrasound (CEUS) imaging of human carotid arteries and the reproduction of this pseudoenhancement in vitro. Seventy patients underwent bilateral CEUS examination of the carotid arteries using a Philips iU22 ultrasound system equipped with a L9-3 ultrasound probe and SonoVue microbubble contrast. During CEUS of the carotid arteries, we identified enhancement in close proximity to the far wall, parallel to the main lumen. The location of this enhancement does not correlate to the anatomical location of a parallel vessel. To corroborate the hypothesis that this is a pseudoenhancement artifact, the enhancement was recreated in a tissue-mimicking material phantom, using the same ultrasound system, settings and contrast agent as the patient study. The phantom study showed that pseudoenhancement may be present during vascular CEUS and that the degree of pseudoenhancement is influenced by the size and concentration of the microbubbles. During vascular CEUS, identification of the artifact is important to prevent misinterpretation of enhancement in and near the far wall.
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Affiliation(s)
- Gerrit L ten Kate
- Division of Pharmacology, Vascular and Metabolic Diseases, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands.
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Thapar A, Shalhoub J, Averkiou M, Mannaris C, Davies AH, Leen ELS. Dose-dependent artifact in the far wall of the carotid artery at dynamic contrast-enhanced US. Radiology 2011; 262:672-9. [PMID: 22156991 DOI: 10.1148/radiol.11110968] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
PURPOSE To quantify a pseudoenhancement phenomenon observed during dynamic contrast material-enhanced ultrasonography (US) of the carotid artery, both in vitro and in vivo. MATERIALS AND METHODS Ethical approval was obtained prior to commencing this prospective case series, and each patient gave written informed consent. Thirty-one patients with 50%-99% internal carotid artery stenosis underwent dynamic contrast-enhanced US of the carotid bifurcation with use of 2 mL of microbubbles. In the final 10 patients, an additional 1 mL bolus was administered after 15 minutes. Raw linear digital imaging and communications in medicine data were analyzed offline. Regions of interest were drawn within the common carotid artery lumen and immediately adjacent to the lumen in the near and far wall adventitia. Peak intensity was measured. An in vitro experiment with a single-channel flow phantom was also performed. This apparatus consisted of an 8-mm-diameter latex tube placed in a tissue-mimicking fluid. Microbubble concentrations of 0.02%, 0.1%, 0.5%, 1%, and 2% were pumped into the tube. Regions of interest were drawn in a similar fashion to the in vivo experiments, and peak intensity was measured. The Wilcoxon signed rank and paired t tests were used to compare the difference between the near and far wall signal intensities at each dose; a multiplication factor comparing near and far wall signal intensity was derived. RESULTS The far wall of the common carotid artery was significantly more echogenic than the near wall at 2 mL contrast agent doses (P<.0001, n=31), and the far wall signal intensity increased synchronously with that of the lumen. The difference in signal intensity between near and far wall regions was significantly greater at 2 mL than at 1 mL (P=.012, n=10). In vitro, the phantom tubing demonstrated a similar pattern and magnitude of enhancement to that seen in vivo. CONCLUSION A dose-dependent, nonlinear propagation artifact known as pseudoenhancement occurs in the far wall adventitia of the carotid artery and should not be mistaken as a marker of plaque vulnerability.
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Affiliation(s)
- Ankur Thapar
- Academic Section of Vascular Surgery and Department of Experimental Medicine, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 0HS, England.
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Tang MX, Mulvana H, Gauthier T, Lim AKP, Cosgrove DO, Eckersley RJ, Stride E. Quantitative contrast-enhanced ultrasound imaging: a review of sources of variability. Interface Focus 2011; 1:520-39. [PMID: 22866229 PMCID: PMC3262271 DOI: 10.1098/rsfs.2011.0026] [Citation(s) in RCA: 184] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 04/26/2011] [Indexed: 12/14/2022] Open
Abstract
Ultrasound provides a valuable tool for medical diagnosis offering real-time imaging with excellent spatial resolution and low cost. The advent of microbubble contrast agents has provided the additional ability to obtain essential quantitative information relating to tissue vascularity, tissue perfusion and even endothelial wall function. This technique has shown great promise for diagnosis and monitoring in a wide range of clinical conditions such as cardiovascular diseases and cancer, with considerable potential benefits in terms of patient care. A key challenge of this technique, however, is the existence of significant variations in the imaging results, and the lack of understanding regarding their origin. The aim of this paper is to review the potential sources of variability in the quantification of tissue perfusion based on microbubble contrast-enhanced ultrasound images. These are divided into the following three categories: (i) factors relating to the scanner setting, which include transmission power, transmission focal depth, dynamic range, signal gain and transmission frequency, (ii) factors relating to the patient, which include body physical differences, physiological interaction of body with bubbles, propagation and attenuation through tissue, and tissue motion, and (iii) factors relating to the microbubbles, which include the type of bubbles and their stability, preparation and injection and dosage. It has been shown that the factors in all the three categories can significantly affect the imaging results and contribute to the variations observed. How these factors influence quantitative imaging is explained and possible methods for reducing such variations are discussed.
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Affiliation(s)
- M.-X. Tang
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
| | - H. Mulvana
- Imaging Sciences Department, Faculty of Medicine, Imperial College London, London W12 0HS, UK
| | - T. Gauthier
- Department of Experimental Medicine and Toxicology, Hammersmith Hospital, Imperial College London, London W12 0NN, UK
| | - A. K. P. Lim
- Hammersmith Hospital, MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, London W12 0NN, UK
| | - D. O. Cosgrove
- Imaging Sciences Department, Faculty of Medicine, Imperial College London, London W12 0HS, UK
| | - R. J. Eckersley
- Imaging Sciences Department, Faculty of Medicine, Imperial College London, London W12 0HS, UK
| | - E. Stride
- Department Mechanical Engineering, University College London, London WC1E 7JE, UK
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Tang MX, Loughran J, Stride E, Zhang D, Eckersley RJ. Effect of bubble shell nonlinearity on ultrasound nonlinear propagation through microbubble populations. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2011; 129:EL76-82. [PMID: 21428471 DOI: 10.1121/1.3544677] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Nonlinear propagation of ultrasound through microbubble populations can generate artifacts and reduce contrast to tissue ratio in ultrasound imaging. The existing propagation model, which underestimates harmonic generation by an order of magnitude, was revised by incorporating a nonlinear constitutive equation for the coating into the description of the microbubble dynamics. Significantly better agreement with experiments was obtained, indicating that coating nonlinearity represents an important contribution to nonlinear propagation of ultrasound in microbubble populations. The results were found to be sensitive to the parameters characterizing the coating nonlinearity and thus accurate measurement of these parameters is required for accurate quantitative predictions.
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Affiliation(s)
- Meng-Xing Tang
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom.
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