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Banahan C, Loughman ME, Keogh MD, Maguire MS. USE OF A NOVEL RADIATION PROTECTION DEVICE TO REDUCE STAFF RADIATION EXPOSURE IN CATH LAB. Phys Med 2022. [DOI: 10.1016/s1120-1797(22)02473-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Loughman ME, Banahan C, Keogh MD, Maguire MS. HISTORICAL PET/CT STAFF DOSE REVIEW AND COMPARISON TO THEORETICAL VALUES. Phys Med 2022. [DOI: 10.1016/s1120-1797(22)02468-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Loughman ME, Banahan C, Keogh MD, Maguire MS. IMPLEMENTATION AND VALIDATION OF IAEA REMOTE X-RAY QC GUIDANCE. Phys Med 2022. [DOI: 10.1016/s1120-1797(22)02311-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Oonan ML, Maguire MS, Gilligan MP, Banahan C, McCann H, O’Connor MN. A TASK BASED DOSIMETRIC ASSESSMENT OF INTERVENTIONAL CARDIOLOGISTS BEHAVIOUR USING A REAL TIME ACTIVE DOSIMETRY SYSTEM. Phys Med 2022. [DOI: 10.1016/s1120-1797(22)02470-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Banahan C, Loughman ME, Keogh MD, Maguire MS. RADIATION EXPOSURE TO TOE OPERATORS DURING CARDIAC INTERVENTIONS. Phys Med 2022. [DOI: 10.1016/s1120-1797(22)02472-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Ince J, Lecchini-Visintini A, Almudayni A, Horsfield MA, Wormleighton J, Banahan C, Chung EML, Minhas JS. Brain tissue motion in acute hemorrhagic stroke using amplified MRI (aMRI). Magn Reson Imaging 2021; 86:17-19. [PMID: 34774985 DOI: 10.1016/j.mri.2021.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 11/10/2021] [Indexed: 10/19/2022]
Abstract
Brain tissue pulsates with each cardiac cycle, however the effect of disease on this natural motion is still unclear. Current literature mainly focuses on healthy brain tissue, with only limited studies looking at disease states such as Chiari malformation and acute ischemic stroke. This case report advances on recent literature by describing the case of a patient with an acute intracerebral hemorrhage and demonstrating an amplified MRI cine of the brain's motion. A clearer understanding of the effects of disease on brain motion may guide clinical application of pulsation measurement.
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Affiliation(s)
- Jonathan Ince
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK; University Hospitals of Leicester NHS Trust, Leicester, UK.
| | - Andrea Lecchini-Visintini
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK; School of Engineering, University of Leicester, Leicester, UK
| | - Alanoud Almudayni
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK; College of Applied Medical Sciences, Prince Sattam bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | | | | | - Caroline Banahan
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Emma M L Chung
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK; University Hospitals of Leicester NHS Trust, Leicester, UK; NIHR Leicester Biomedical Research Centre, University of Leicester, Leicester, UK; School of Life Course Sciences, King's College London, London, UK
| | - Jatinder S Minhas
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK; University Hospitals of Leicester NHS Trust, Leicester, UK; NIHR Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
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Turner P, Banahan C, Alharbi M, Ince J, Venturini S, Berger S, Bnini I, Campbell J, Beach KW, Horsfield M, Oura M, Lecchini-Visintini A, Chung EML. Brain Tissue Pulsation in Healthy Volunteers. Ultrasound Med Biol 2020; 46:3268-3278. [PMID: 32980160 DOI: 10.1016/j.ultrasmedbio.2020.08.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 07/16/2020] [Accepted: 08/20/2020] [Indexed: 06/11/2023]
Abstract
It is well known that the brain pulses with each cardiac cycle, but interest in measuring cardiac-induced brain tissue pulsations (BTPs) is relatively recent. This study was aimed at generating BTP reference data from healthy patients for future clinical comparisons and modelling. BTPs were measured through the forehead and temporal positions as a function of age, sex, heart rate, mean arterial pressure and pulse pressure. A multivariate regression model was developed based on transcranial tissue Doppler BTP measurements from 107 healthy adults (56 male) aged from 20-81 y. A subset of 5 participants (aged 20-49 y) underwent a brain magnetic resonance imaging scan to relate the position of the ultrasound beam to anatomy. BTP amplitudes were found to vary widely between patients (from ∼4 to ∼150 µm) and were strongly associated with pulse pressure. Comparison with magnetic resonance images confirmed regional variations in BTP with depth and probe position.
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Affiliation(s)
- Poppy Turner
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK; Department of Engineering, University of Leicester, Leicester, UK
| | - Caroline Banahan
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK; Department of Medical Physics, University Hospitals of Leicester NHS Trust, Leicester, UK
| | - Meshal Alharbi
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Jonathan Ince
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Sara Venturini
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Stefanie Berger
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Imane Bnini
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - James Campbell
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Kirk W Beach
- University of Washington, Seattle, Washington, USA
| | | | | | | | - Emma M L Chung
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK; Department of Medical Physics, University Hospitals of Leicester NHS Trust, Leicester, UK; Leicester Cardiovascular Biomedical Research Centre, Leicester, UK.
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Patel N, Banahan C, Janus J, Horsfield MA, Cox A, Marshall D, Colman J, Morlese J, Evans DH, Hannon C, Egan V, Garrard P, Hague JP, Chung EML. Neurological impact of emboli during adult cardiac surgery. J Neurol Sci 2020; 416:117006. [PMID: 32623144 PMCID: PMC7718579 DOI: 10.1016/j.jns.2020.117006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 06/05/2020] [Accepted: 06/19/2020] [Indexed: 11/29/2022]
Abstract
Objectives This study draws on advances in Doppler ultrasound bubble sizing to investigate whether high volumes of macro-bubbles entering the brain during cardiac surgery increase the risk of new cerebral microbleeds (CMBs), ischemic MR lesions, or post-operative cognitive decline (POCD). Methods Transcranial Doppler (TCD) ultrasound recordings were analysed to estimate numbers of emboli and macrobubbles (>100 μm) entering the brain during cardiac surgery. Logistic regression was used to explore the hypothesis that emboli characteristics affect the incidence of new brain injuries identified through pre- and post-operative MRI and neuropsychological testing. Results TCD, MRI, and neuropsychological test data were compared between 28 valve and 18 CABG patients. Although valve patients received over twice as many emboli per procedure [median: 1995 vs. 859, p = .004], and seven times as many macro-bubbles [median: 218 vs. 28, p = .001], high volumes of macrobubbles were not found to be significantly associated with new CMBs, new ischaemic lesions, or POCD. The odds of acquiring new CMBs increased by approximately 5% [95% CI: 1 to 10%] for every embolus detected in the first minute after the release of the aortic cross-clamp (AxC). Logistic regression models also confirmed previous findings that cardiopulmonary bypass time and valve surgery were significant predictors for new CMBs (both p = .03). Logistic regression analysis estimated an increase in the odds of acquiring new CMBs of 6% [95% CI: 1 to 12%] for every minute of bypass time over 91 mins. Conclusions This small study provides new information about the properties and numbers of bubbles entering the brain during surgery, but found no evidence to substantiate a direct link between large numbers of macrobubbles and adverse cognitive or MR outcome. Clinical Trial Registration URL - http://www.isrctn.com. Unique identifier: 66022965. Higher numbers of macrobubbles enter the brain during valve surgery compared to bypass graft surgery. Macrobubbles did not appear to be linked to new cerebral microbleeds, ischemic lesions, or cognitive decline. Emboli received following release of the aortic cross-clamp predicted new cerebral microbleeds. Other factors predicting new microbleeds included cardiopulmonary bypass duration and surgery type.
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Affiliation(s)
- Nikil Patel
- Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK; Leicester Biomedical Research Centre, Glenfield Hospital, Leicester LE3 9QP, UK; Department of Clinical Neurosciences, St George's, University of London, London SW17 ORE, UK
| | - Caroline Banahan
- Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK
| | - Justyna Janus
- Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK
| | - Mark A Horsfield
- Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK
| | - Anthony Cox
- Department of Clinical Neurosciences, St George's, University of London, London SW17 ORE, UK
| | - David Marshall
- Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK
| | - Jordan Colman
- Department of Clinical Neurosciences, St George's, University of London, London SW17 ORE, UK
| | - John Morlese
- University Hospitals of Leicester NHS Trust, Leicester LE1 5WW, UK
| | - David H Evans
- Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK
| | - Claire Hannon
- Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK
| | - Vincent Egan
- Department of Psychiatry and Applied Psychology, University of Nottingham, Nottingham NG8 1BB, UK
| | - Peter Garrard
- Department of Clinical Neurosciences, St George's, University of London, London SW17 ORE, UK
| | - James P Hague
- School of Physical Sciences, The Open University, Walton Hall, Milton Keyns, MK7 6AA, UK
| | - Emma M L Chung
- Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, UK; Leicester Biomedical Research Centre, Glenfield Hospital, Leicester LE3 9QP, UK; University Hospitals of Leicester NHS Trust, Leicester LE1 5WW, UK.
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Patel N, Banahan C, Janus J, Horsfield MA, Cox A, Li X, Cappellugola L, Colman J, Egan V, Garrard P, Chung EM. Perioperative Cerebral Microbleeds After Adult Cardiac Surgery. Stroke 2019; 50:336-343. [PMID: 30572811 PMCID: PMC6354910 DOI: 10.1161/strokeaha.118.023355] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Background and Purpose- Cerebral microbleeds (CMBs) have been observed using magnetic resonance imaging in patients with cardiovascular risk factors, cognitive deterioration, small vessel disease, and dementia. They are a well-known consequence of cerebral amyloid angiopathy, chronic hypertension, and diffuse axonal injury, among other causes. However, the frequency and location of new CMBs postadult cardiac surgery, in association with cognition and perioperative risk factors, have yet to be studied. Methods- Pre- and postsurgery magnetic resonance susceptibility-weighted images and neuropsychological tests were analyzed from a total of 75 patients undergoing cardiac surgery (70 men; mean age, 63±10 years). CMBs were identified by a neuroradiologist blinded to clinical details who independently assessed the presence and location of CMBs using standardized criteria. Results- New CMBs were identified in 76% of patients after cardiac surgery. The majority of new CMBs were located in the frontal lobe (46%) followed by the parietal lobe (15%), cerebellum (13%), occipital lobe (12%), and temporal lobe (8%). Patients with new CMBs typically began with a higher prevalence of preexisting CMBs ( P=0.02). New CMBs were associated with longer cardiopulmonary bypass times ( P=0.003), and there was a borderline association with lower percentage hematocrit ( P=0.04). Logistic regression analysis suggested a ≈2% increase in the odds of acquiring new CMBs during cardiac surgery for every minute of bypass time (odds ratio, 1.02; 95% CI, 1.00-1.05; P=0.04). Postoperative neuropsychological decline was observed in 44% of patients and seemed to be unrelated to new CMBs. Conclusions- New CMBs identified using susceptibility-weighted images were found in 76% of patients who underwent cardiac surgery. CMBs were globally distributed with the highest numbers in the frontal and parietal lobes. Our regression analysis indicated that length of cardiopulmonary bypass time and lowered hematocrit may be significant predictors for new CMBs after cardiac surgery. Clinical Trial Registration- URL: http://www.isrctn.com . Unique identifier: 66022965.
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Affiliation(s)
- Nikil Patel
- From the Department of Cardiovascular Sciences, University of Leicester, United Kingdom (N.P., J.J., M.A.H., L.C., E.M.L.C.)
- NIHR Leicester Biomedical Research Centre–Cardiovascular Theme, Glenfield Hospital, United Kingdom (N.P., E.M.L.C.)
- Department of Clinical Neurosciences, St George’s, University of London, United Kingdom (N.P., X.L., J.C., P.G.)
| | - Caroline Banahan
- Department of Medical Physics, University Hospitals of Leicester NHS Trust, United Kingdom (C.B., E.M.L.C.)
| | - Justyna Janus
- From the Department of Cardiovascular Sciences, University of Leicester, United Kingdom (N.P., J.J., M.A.H., L.C., E.M.L.C.)
| | - Mark A. Horsfield
- From the Department of Cardiovascular Sciences, University of Leicester, United Kingdom (N.P., J.J., M.A.H., L.C., E.M.L.C.)
| | - Anthony Cox
- Neuroradiology Department, St George’s Hospital, London, United Kingdom (A.C.)
| | - Xingfeng Li
- Department of Clinical Neurosciences, St George’s, University of London, United Kingdom (N.P., X.L., J.C., P.G.)
| | - Laurie Cappellugola
- From the Department of Cardiovascular Sciences, University of Leicester, United Kingdom (N.P., J.J., M.A.H., L.C., E.M.L.C.)
| | - Jordan Colman
- Department of Clinical Neurosciences, St George’s, University of London, United Kingdom (N.P., X.L., J.C., P.G.)
| | - Vincent Egan
- Department of Psychiatry and Applied Psychology, University of Nottingham, United Kingdom (V.E.)
| | - Peter Garrard
- Department of Clinical Neurosciences, St George’s, University of London, United Kingdom (N.P., X.L., J.C., P.G.)
| | - Emma M.L. Chung
- From the Department of Cardiovascular Sciences, University of Leicester, United Kingdom (N.P., J.J., M.A.H., L.C., E.M.L.C.)
- NIHR Leicester Biomedical Research Centre–Cardiovascular Theme, Glenfield Hospital, United Kingdom (N.P., E.M.L.C.)
- Department of Medical Physics, University Hospitals of Leicester NHS Trust, United Kingdom (C.B., E.M.L.C.)
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Patel N, Horsfield MA, Banahan C, Thomas AG, Nath M, Nath J, Ambrosi PB, Chung EML. Detection of Focal Longitudinal Changes in the Brain by Subtraction of MR Images. AJNR Am J Neuroradiol 2017; 38:923-927. [PMID: 28364006 DOI: 10.3174/ajnr.a5165] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 12/14/2016] [Indexed: 01/19/2023]
Abstract
BACKGROUND AND PURPOSE The detection of new subtle brain pathology on MR imaging is a time-consuming and error-prone task for the radiologist. This article introduces and evaluates an image-registration and subtraction method for highlighting small changes in the brain with a view to minimizing the risk of missed pathology and reducing fatigue. MATERIALS AND METHODS We present a fully automated algorithm for highlighting subtle changes between multiple serially acquired brain MR images with a novel approach to registration and MR imaging bias field correction. The method was evaluated for the detection of new lesions in 77 patients undergoing cardiac surgery, by using pairs of fluid-attenuated inversion recovery MR images acquired 1-2 weeks before the operation and 6-8 weeks postoperatively. Three radiologists reviewed the images. RESULTS On the basis of qualitative comparison of pre- and postsurgery FLAIR images, radiologists identified 37 new ischemic lesions in 22 patients. When these images were accompanied by a subtraction image, 46 new ischemic lesions were identified in 26 patients. After we accounted for interpatient and interradiologist variability using a multilevel statistical model, the likelihood of detecting a lesion was 2.59 (95% CI, 1.18-5.67) times greater when aided by the subtraction algorithm (P = .017). Radiologists also reviewed the images significantly faster (P < .001) by using the subtraction image (mean, 42 seconds; 95% CI, 29-60 seconds) than through qualitative assessment alone (mean, 66 seconds; 95% CI, 46-96 seconds). CONCLUSIONS Use of this new subtraction algorithm would result in considerable savings in the time required to review images and in improved sensitivity to subtle focal pathology.
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Affiliation(s)
- N Patel
- From the Department of Cardiovascular Sciences (N.P., M.A.H., M.N., J.N., E.M.L.C.), University of Leicester, Leicester Royal Infirmary, Leicester, UK.,Leicester National Institute of Health Research Cardiovascular Biomedical Research Unit (N.P., E.M.L.C.), Glenfield Hospital, Leicester, UK
| | - M A Horsfield
- From the Department of Cardiovascular Sciences (N.P., M.A.H., M.N., J.N., E.M.L.C.), University of Leicester, Leicester Royal Infirmary, Leicester, UK
| | - C Banahan
- Medical Physics (C.B., E.M.L.C.), University Hospitals of Leicester National Health Service Trust, Leicester, UK
| | - A G Thomas
- Departments of Radiology (A.G.T., P.B.A.)
| | - M Nath
- From the Department of Cardiovascular Sciences (N.P., M.A.H., M.N., J.N., E.M.L.C.), University of Leicester, Leicester Royal Infirmary, Leicester, UK
| | - J Nath
- From the Department of Cardiovascular Sciences (N.P., M.A.H., M.N., J.N., E.M.L.C.), University of Leicester, Leicester Royal Infirmary, Leicester, UK
| | - P B Ambrosi
- Departments of Radiology (A.G.T., P.B.A.).,Neuri Beaujon (P.B.A.), University Paris Diderot, Paris, France
| | - E M L Chung
- From the Department of Cardiovascular Sciences (N.P., M.A.H., M.N., J.N., E.M.L.C.), University of Leicester, Leicester Royal Infirmary, Leicester, UK .,Leicester National Institute of Health Research Cardiovascular Biomedical Research Unit (N.P., E.M.L.C.), Glenfield Hospital, Leicester, UK.,Medical Physics (C.B., E.M.L.C.), University Hospitals of Leicester National Health Service Trust, Leicester, UK
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Affiliation(s)
- Nikil Patel
- From the Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom (N.P., M.A.H., C.B., J.J., K.M., E.C.); Leicester NIHR Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, United Kingdom (N.P., E.C.); University Hospitals of Leicester NHS Trust, Leicester, United Kingdom (M.A.H., C.B., J.M., E.C.); and Faculty of Psychology and Medicine, University of Nottingham, Nottingham, United Kingdom (V.E.)
| | - Mark A. Horsfield
- From the Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom (N.P., M.A.H., C.B., J.J., K.M., E.C.); Leicester NIHR Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, United Kingdom (N.P., E.C.); University Hospitals of Leicester NHS Trust, Leicester, United Kingdom (M.A.H., C.B., J.M., E.C.); and Faculty of Psychology and Medicine, University of Nottingham, Nottingham, United Kingdom (V.E.)
| | - Caroline Banahan
- From the Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom (N.P., M.A.H., C.B., J.J., K.M., E.C.); Leicester NIHR Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, United Kingdom (N.P., E.C.); University Hospitals of Leicester NHS Trust, Leicester, United Kingdom (M.A.H., C.B., J.M., E.C.); and Faculty of Psychology and Medicine, University of Nottingham, Nottingham, United Kingdom (V.E.)
| | - Justyna Janus
- From the Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom (N.P., M.A.H., C.B., J.J., K.M., E.C.); Leicester NIHR Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, United Kingdom (N.P., E.C.); University Hospitals of Leicester NHS Trust, Leicester, United Kingdom (M.A.H., C.B., J.M., E.C.); and Faculty of Psychology and Medicine, University of Nottingham, Nottingham, United Kingdom (V.E.)
| | - Katie Masters
- From the Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom (N.P., M.A.H., C.B., J.J., K.M., E.C.); Leicester NIHR Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, United Kingdom (N.P., E.C.); University Hospitals of Leicester NHS Trust, Leicester, United Kingdom (M.A.H., C.B., J.M., E.C.); and Faculty of Psychology and Medicine, University of Nottingham, Nottingham, United Kingdom (V.E.)
| | - John Morlese
- From the Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom (N.P., M.A.H., C.B., J.J., K.M., E.C.); Leicester NIHR Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, United Kingdom (N.P., E.C.); University Hospitals of Leicester NHS Trust, Leicester, United Kingdom (M.A.H., C.B., J.M., E.C.); and Faculty of Psychology and Medicine, University of Nottingham, Nottingham, United Kingdom (V.E.)
| | - Vincent Egan
- From the Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom (N.P., M.A.H., C.B., J.J., K.M., E.C.); Leicester NIHR Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, United Kingdom (N.P., E.C.); University Hospitals of Leicester NHS Trust, Leicester, United Kingdom (M.A.H., C.B., J.M., E.C.); and Faculty of Psychology and Medicine, University of Nottingham, Nottingham, United Kingdom (V.E.)
| | - Emma M.L. Chung
- From the Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom (N.P., M.A.H., C.B., J.J., K.M., E.C.); Leicester NIHR Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, United Kingdom (N.P., E.C.); University Hospitals of Leicester NHS Trust, Leicester, United Kingdom (M.A.H., C.B., J.M., E.C.); and Faculty of Psychology and Medicine, University of Nottingham, Nottingham, United Kingdom (V.E.)
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Banahan C, Rogerson Z, Rousseau C, Ramnarine KV, Evans DH, Chung EML. An in vitro comparison of embolus differentiation techniques for clinically significant macroemboli: dual-frequency technique versus frequency modulation method. Ultrasound Med Biol 2014; 40:2642-2654. [PMID: 25218455 PMCID: PMC4195753 DOI: 10.1016/j.ultrasmedbio.2014.06.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 05/12/2014] [Accepted: 06/03/2014] [Indexed: 06/03/2023]
Abstract
The ability to distinguish harmful solid cerebral emboli from gas bubbles intra-operatively has potential to direct interventions to reduce the risk of brain injury. In this in vitro study, two embolus discrimination techniques, dual-frequency (DF) and frequency modulation (FM) methods, are simultaneously compared to assess discrimination of potentially harmful large pieces of carotid plaque debris (0.5-1.55 mm) and thrombus-mimicking material (0.5-2 mm) from gas bubbles (0.01-2.5 mm). Detection of plaque and thrombus-mimic using the DF technique yielded disappointing results, with four out of five particles being misclassified (sensitivity: 18%; specificity: 89%). Although the FM method offered improved sensitivity, a higher number of false positives were observed (sensitivity: 72%; specificity: 50%). Optimum differentiation was achieved using the difference between peak embolus/blood ratio and mean embolus/blood ratio (sensitivity: 77%; specificity: 81%). We conclude that existing DF and FM techniques are unable to confidently distinguish large solid emboli from small gas bubbles (<50 μm).
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Affiliation(s)
- Caroline Banahan
- Medical Physics Department, University Hospitals of Leicester NHS Trust, Leicester, UK.
| | - Zach Rogerson
- Department of Physics, University of Leicester, Leicester, UK
| | - Clément Rousseau
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | | | - David H Evans
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Emma M L Chung
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
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Abstract
Bubbles introduced to the arterial circulation during invasive medical procedures can have devastating consequences for brain function but their effects are currently difficult to quantify. Here we present a Monte Carlo simulation investigating the impact of gas bubbles on cerebral blood flow. For the first time, this model includes realistic adhesion forces, bubble deformation, fluid dynamical considerations, and bubble dissolution. This allows investigation of the effects of buoyancy, solubility, and blood pressure on embolus clearance. Our results illustrate that blockages depend on several factors, including the number and size distribution of incident emboli, dissolution time and blood pressure. We found it essential to model the deformation of bubbles to avoid overestimation of arterial obstruction. Incorporation of buoyancy effects within our model slightly reduced the overall level of obstruction but did not decrease embolus clearance times. We found that higher blood pressures generate lower levels of obstruction and improve embolus clearance. Finally, we demonstrate the effects of gas solubility and discuss potential clinical applications of the model.
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Affiliation(s)
- J P Hague
- Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK.
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Banahan C, Hague JP, Evans DH, Patel R, Ramnarine KV, Chung EML. Sizing gaseous emboli using Doppler embolic signal intensity. Ultrasound Med Biol 2012; 38:824-833. [PMID: 22402022 PMCID: PMC3356576 DOI: 10.1016/j.ultrasmedbio.2012.01.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 12/15/2011] [Accepted: 01/11/2012] [Indexed: 05/31/2023]
Abstract
Extension of transcranial Doppler embolus detection to estimation of bubble size has historically been hindered by difficulties in applying scattering theory to the interpretation of clinical data. This article presents a simplified approach to the sizing of air emboli based on analysis of Doppler embolic signal intensity, by using an approximation to the full scattering theory that can be solved to estimate embolus size. Tests using simulated emboli show that our algorithm is theoretically capable of sizing 90% of "emboli" to within 10% of their true radius. In vitro tests show that 69% of emboli can be sized to within 20% of their true value under ideal conditions, which reduces to 30% of emboli if the beam and vessel are severely misaligned. Our results demonstrate that estimation of bubble size during clinical monitoring could be used to distinguish benign microbubbles from potentially harmful macrobubbles during intraoperative clinical monitoring.
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Affiliation(s)
- Caroline Banahan
- Medical Physics Department, University Hospitals of Leicester NHS Trust, Leicester, United Kingdom.
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