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Sotiriou M, Damianou C. Evaluating acoustic and thermal properties of a plaque phantom. J Ultrasound 2024; 27:457-470. [PMID: 37031317 PMCID: PMC11333666 DOI: 10.1007/s40477-023-00778-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 02/07/2023] [Indexed: 04/10/2023] Open
Abstract
PURPOSE The aim of this study is to evaluate the acoustic and thermal properties of a plaque phantom. This is very important for the effective implementation of ultrasound not only in diagnosis but especially in treatment for the future. MATERIAL AND METHODS An evaluation of acoustic and thermal properties of plaque phantoms to test their suitability mainly for ultrasound imaging and therapy was presented. The evaluation included measurements of the acoustic propagation speed using pulse-echo technique, ultrasonic attenuation coefficient using through transmission immersion technique, and absorption coefficient. Moreover, thermal properties (thermal conductivity, volumetric specific heat capacity and thermal diffusivity) were measured with the transient method using a needle probe. RESULTS It was shown that acoustic and thermal properties of atherosclerotic plaque phantoms fall well within the range of reported values for atherosclerotic plaque and slightly different for thermal diffusivity and volumetric specific heat capacity for soft tissues. The mean value of acoustic and thermal properties and their standard deviation of plaque phantoms were 1523 ± 23 m/s for acoustic speed, 0.50 ± 0.02 W/mK for thermal conductivity, 0.30 ± 0.21 db/cm-MHz for ultrasonic absorption coefficient and 1.63 ± 0.46 db/cm-MHz for ultrasonic attenuation coefficient. CONCLUSIONS This study demonstrated that acoustic and thermal properties of atherosclerotic plaque phantoms were within the range of reported values. Future studies should be focused on the optimum recipe of the atherosclerotic plaque phantoms that mimics the human atherosclerotic plaque (agar 4% w/v, gypsum 10% w/v and butter 10% w/v) and can be used for HIFU therapy.
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Affiliation(s)
- Michalis Sotiriou
- Electrical Engineering Department, Cyprus University of Technology, 30 Archbishop Kyprianos Street, 3036, Limassol, Cyprus
| | - Christakis Damianou
- Electrical Engineering Department, Cyprus University of Technology, 30 Archbishop Kyprianos Street, 3036, Limassol, Cyprus.
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2
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Henriques J, Amaro AM, Piedade AP. Biomimicking Atherosclerotic Vessels: A Relevant and (Yet) Sub-Explored Topic. Biomimetics (Basel) 2024; 9:135. [PMID: 38534820 DOI: 10.3390/biomimetics9030135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 02/20/2024] [Accepted: 02/21/2024] [Indexed: 03/28/2024] Open
Abstract
Atherosclerosis represents the etiologic source of several cardiovascular events, including myocardial infarction, cerebrovascular accidents, and peripheral artery disease, which remain the leading cause of mortality in the world. Numerous strategies are being delineated to revert the non-optimal projections of the World Health Organization, by both designing new diagnostic and therapeutic approaches or improving the interventional procedures performed by physicians. Deeply understanding the pathological process of atherosclerosis is, therefore, mandatory to accomplish improved results in these trials. Due to their availability, reproducibility, low expensiveness, and rapid production, biomimicking physical models are preferred over animal experimentation because they can overcome some limitations, mainly related to replicability and ethical issues. Their capability to represent any atherosclerotic stage and/or plaque type makes them valuable tools to investigate hemodynamical, pharmacodynamical, and biomechanical behaviors, as well as to optimize imaging systems and, thus, obtain meaningful prospects to improve the efficacy and effectiveness of treatment on a patient-specific basis. However, the broadness of possible applications in which these biomodels can be used is associated with a wide range of tissue-mimicking materials that are selected depending on the final purpose of the model and, consequently, prioritizing some materials' properties over others. This review aims to summarize the progress in fabricating biomimicking atherosclerotic models, mainly focusing on using materials according to the intended application.
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Affiliation(s)
- Joana Henriques
- University of Coimbra, CEMMPRE, ARISE, Department of Mechanical Engineering, 3030-788 Coimbra, Portugal
| | - Ana M Amaro
- University of Coimbra, CEMMPRE, ARISE, Department of Mechanical Engineering, 3030-788 Coimbra, Portugal
| | - Ana P Piedade
- University of Coimbra, CEMMPRE, ARISE, Department of Mechanical Engineering, 3030-788 Coimbra, Portugal
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Wang T, Pfeiffer T, Akyildiz A, van Beusekom HMM, Huber R, van der Steen AFW, van Soest G. Intravascular optical coherence elastography. BIOMEDICAL OPTICS EXPRESS 2022; 13:5418-5433. [PMID: 36425628 PMCID: PMC9664873 DOI: 10.1364/boe.470039] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 08/30/2022] [Accepted: 08/31/2022] [Indexed: 05/07/2023]
Abstract
Optical coherence elastography (OCE), a functional extension of optical coherence tomography (OCT), visualizes tissue strain to deduce the tissue's biomechanical properties. In this study, we demonstrate intravascular OCE using a 1.1 mm motorized catheter and a 1.6 MHz Fourier domain mode-locked OCT system. We induced an intraluminal pressure change by varying the infusion rate from the proximal end of the catheter. We analysed the pixel-matched phase change between two different frames to yield the radial strain. Imaging experiments were carried out in a phantom and in human coronary arteries in vitro. At an imaging speed of 3019 frames/s, we were able to capture the dynamic strain. Stiff inclusions in the phantom and calcification in atherosclerotic plaques are associated with low strain values and can be distinguished from the surrounding soft material, which exhibits elevated strain. For the first time, circumferential intravascular OCE images are provided side by side with conventional OCT images, simultaneously mapping both the tissue structure and stiffness.
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Affiliation(s)
- Tianshi Wang
- Thoraxcentre, Erasmus University Medical Centre, Rotterdam 3015 AA, The Netherlands
| | - Tom Pfeiffer
- Institut für Biomedizinische Optik, Universität zu Lübeck, Lübeck 23562, Germany
| | - Ali Akyildiz
- Thoraxcentre, Erasmus University Medical Centre, Rotterdam 3015 AA, The Netherlands
- Department of Biomechanical Engineering, Delft University of Technology, Delft 2600 AA, The Netherlands
| | | | - Robert Huber
- Institut für Biomedizinische Optik, Universität zu Lübeck, Lübeck 23562, Germany
| | - Antonius F. W. van der Steen
- Thoraxcentre, Erasmus University Medical Centre, Rotterdam 3015 AA, The Netherlands
- Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518005, China
- Department of Imaging Science and Technology, Delft University of Technology, Delft 2600 AA, The Netherlands
| | - Gijs van Soest
- Thoraxcentre, Erasmus University Medical Centre, Rotterdam 3015 AA, The Netherlands
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Sotiriou M, Yiannakou M, Damianou C. Investigating atherosclerotic plaque phantoms for ultrasound therapy. J Ultrasound 2022; 25:709-720. [PMID: 35098435 PMCID: PMC9402861 DOI: 10.1007/s40477-022-00658-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 01/12/2022] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The aim of the proposed study was to conduct a feasibility study using a flat rectangular (2 × 10 mm2) transducer operating at 4.0 MHz for creating thermal lesions in an arterial atherosclerotic plaque phantom. The proposed method can be used in the future for treating atherosclerotic plaques in human arteries. MATERIALS AND METHODS The flat rectangular transducer was firstly assessed in agar/silica evaporated milk phantom, polyacrylamide phantom and freshly excised turkeytissue phantom. Then, the same transducer was assessed in an arterial atherosclerotic plaque phantom which was created in the laboratory with a very low cost. The recipe of the atherosclerotic plaque phantom was 4% w/v agar, 1% w/v gypsum, 2% w/v butter and 93% water. The amount of plaque removal was evaluated visually and using an X-Ray system. RESULTS It was shown that the flat rectangular transducer can create thermal lesions on the agar/silica evaporated milk phantom, polyacrylamide phantom and in excised tissue. The size of the lesions matches the geometry of the transducer. Moreover, this transducer destroyed 27.1% of the atherosclerotic plaque phantom with 8 W acoustical power and 30 s duration. CONCLUSIONS This feasibility study demonstrated that atherosclerotic plaque can be destroyed using a very small flat rectangular (2 × 10 mm2) transducer in a very small time interval of 30 s. In future clinical trials the transducer will be incorporated in a catheter which will be inserted intravascular (1-3 mm) wide and can be used to treat atherosclerotic plaques in the coronary arteries.
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Affiliation(s)
- Michalis Sotiriou
- Electrical Engineering Department, Cyprus University of Technology, 30 Archbishop Kyprianos Street, 3036 Limassol, Cyprus
| | - Marinos Yiannakou
- Electrical Engineering Department, Cyprus University of Technology, 30 Archbishop Kyprianos Street, 3036 Limassol, Cyprus
| | - Christakis Damianou
- Electrical Engineering Department, Cyprus University of Technology, 30 Archbishop Kyprianos Street, 3036 Limassol, Cyprus
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Wang A, Qi W, Gao T, Tang X. Molecular Contrast Optical Coherence Tomography and Its Applications in Medicine. Int J Mol Sci 2022; 23:ijms23063038. [PMID: 35328454 PMCID: PMC8949853 DOI: 10.3390/ijms23063038] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 03/05/2022] [Accepted: 03/08/2022] [Indexed: 12/28/2022] Open
Abstract
The growing need to understand the molecular mechanisms of diseases has prompted the revolution in molecular imaging techniques along with nanomedicine development. Conventional optical coherence tomography (OCT) is a low-cost in vivo imaging modality that provides unique high spatial and temporal resolution anatomic images but little molecular information. However, given the widespread adoption of OCT in research and clinical practice, its robust molecular imaging extensions are strongly desired to combine with anatomical images. A range of relevant approaches has been reported already. In this article, we review the recent advances of molecular contrast OCT imaging techniques, the corresponding contrast agents, especially the nanoparticle-based ones, and their applications. We also summarize the properties, design criteria, merit, and demerit of those contrast agents. In the end, the prospects and challenges for further research and development in this field are outlined.
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Lee H, Seeger MR, Lippok N, Nadkarni SK, van Soest G, Bouma BE. Nanosecond SRS fiber amplifier for label-free near-infrared photoacoustic microscopy of lipids. PHOTOACOUSTICS 2022; 25:100331. [PMID: 35096525 PMCID: PMC8783138 DOI: 10.1016/j.pacs.2022.100331] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/05/2022] [Accepted: 01/14/2022] [Indexed: 05/18/2023]
Abstract
Near-infrared photoacoustics receives increasing interest as an intravital modality to sense key biomolecules. One of the most central types of biomolecules of interest are lipids as they constitute essential bio-hallmarks of cardiovascular and metabolic diseases and their in-vivo detection holds insightful information about disease progression and treatment monitoring. However, the full potential of near-infrared photoacoustic for high-resolution and high-sensitivity biomedical studies of lipids has so far not been exploited due a lack of appropriate excitation sources delivering short-pulses at high-repetition-rate, high-pulse-energy, and wavelength around 1200 nm. Here, we demonstrate a custom-built SRS fiber amplifier that provides optical excitations at 1192.8 nm, repetition rates of 200 kHz, pulse durations below 2 ns, and pulse energies beyond 5 μJ. We capitalize on the performance of our excitation source and show near-infrared photoacoustics resolving intrinsic lipid contrast in biomedically relevant specimens ranging from single cells to lipid-rich tissue with subcellular resolution.
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Affiliation(s)
- Hwidon Lee
- Harvard Medical School, Boston, Massachusetts, MA 02115, USA
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, 40 Blossom Street, Boston, MA 02114, USA
| | - Markus R. Seeger
- Harvard Medical School, Boston, Massachusetts, MA 02115, USA
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, 40 Blossom Street, Boston, MA 02114, USA
| | - Norman Lippok
- Harvard Medical School, Boston, Massachusetts, MA 02115, USA
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, 40 Blossom Street, Boston, MA 02114, USA
| | - Seemantini K. Nadkarni
- Harvard Medical School, Boston, Massachusetts, MA 02115, USA
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, 40 Blossom Street, Boston, MA 02114, USA
| | - Gijs van Soest
- Department of Biomedical Engineering, Erasmus Medical Center, PO Box 2040, 3000 Rotterdam, CA The Netherlands
| | - Brett E. Bouma
- Harvard Medical School, Boston, Massachusetts, MA 02115, USA
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, 40 Blossom Street, Boston, MA 02114, USA
- Department of Biomedical Engineering, Erasmus Medical Center, PO Box 2040, 3000 Rotterdam, CA The Netherlands
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
- Corresponding author at: Harvard Medical School, Boston, Massachusetts, MA 02115, USA.
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Otsuka K, Villiger M, Nadkarni SK, Bouma BE. Intravascular Polarimetry: Clinical Translation and Future Applications of Catheter-Based Polarization Sensitive Optical Frequency Domain Imaging. Front Cardiovasc Med 2020; 7:146. [PMID: 33005632 PMCID: PMC7485575 DOI: 10.3389/fcvm.2020.00146] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Accepted: 07/10/2020] [Indexed: 11/13/2022] Open
Abstract
Optical coherence tomography (OCT) and optical frequency domain imaging (OFDI) visualize the coronary artery wall and plaque morphology in great detail. The advent of these high-resolution intracoronary imaging modalities has propelled our understanding of coronary atherosclerosis and provided enhanced guidance for percutaneous coronary intervention. Yet, the lack of contrast between distinct tissue types and plaque compositions impedes further elucidation of the complex mechanisms that contribute to acute coronary syndrome (ACS) and hinders the prospective identification of plaques susceptible to rupture. Intravascular polarimetry with polarization-sensitive OFDI measures polarization properties of the coronary arterial wall using conventional intravascular imaging catheters. The quantitative polarization metrics display notable image contrast between several relevant coronary plaque microstructures that are difficult to identify with conventional OCT and OFDI. Tissues rich in collagen and smooth muscle cells exhibit birefringence, while lipid and macrophages cause depolarization. In this review, we describe the basic principles of intravascular polarimetry, discuss the interpretation of the polarization signatures, and outline promising avenues for future research and clinical implications.
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Affiliation(s)
- Kenichiro Otsuka
- Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, Boston, MA, United States
| | - Martin Villiger
- Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, Boston, MA, United States
| | - Seemantini K Nadkarni
- Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, Boston, MA, United States
| | - Brett E Bouma
- Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, Boston, MA, United States.,Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, United States.,Department of Cardiology, Erasmus University Medical Center, Rotterdam, Netherlands
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8
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Freund JE, Faber DJ, Bus MT, van Leeuwen TG, de Bruin DM. Grading upper tract urothelial carcinoma with the attenuation coefficient of in-vivo optical coherence tomography. Lasers Surg Med 2019; 51:399-406. [PMID: 30919487 DOI: 10.1002/lsm.23079] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2019] [Indexed: 12/19/2022]
Abstract
INTRODUCTION With catheter based optical coherence tomography (OCT), high resolution images of the upper urinary tract can be obtained, thereby facilitating the detection of upper tract urothelial carcinomas (UTUC). We hypothesized that the attenuation coefficient of the OCT signal (μOCT ) is related to the histopathologic grade of the tumor. OBJECTIVES In this study, we aimed to define the μOCT cut-off for discriminating high grade and low grade papillary UTUC. METHODS For this post-hoc analysis, data from OCT imaging of papillary UTUC was obtained from patients during ureterorenoscopy. OCT images and raw data were simultaneously analyzed with in-house developed software. The μOCT determined in papillary UTUCs and corresponding histopathologic grading from either biopsies or radical resection specimens were compared. RESULTS Thirty-five papillary UTUC from 35 patients were included. μOCT analysis was feasible in all cases. The median μOCT was 3.3 mm-1 (IQR 2.7-3.7 mm-1 ) for low-grade UTUC and 4.9 mm-1 (IQR 4.3-6.1 mm-1 ) for high-grade UTUC (P = 0.004). ROC analysis yielded a μOCT cut-off value of >4.0 mm-1 (AUC = 0.85, P < 0.001) with a sensitivity of 83% and a specificity of 94% for high-grade papillary UTUC. CONCLUSIONS This study proposes a μOCT cut-off of 4.0 mm-1 for quantitative grading of UTUC with ureterorenoscopic OCT imaging. The promising diagnostic accuracy calculations justify further studies to validate the proposed cut-off value. Implementation of the software for the μOCT analysis in OCT systems may allow for μOCT assessment at real time during ureterorenoscopy. Lasers Surg. Med. 51:399-406, 2019. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Jan Erik Freund
- Department of Urology, Amsterdam UMC, University of Amsterdam, Cancer Center Amsterdam, Amsterdam, The Netherlands
| | - Dirk J Faber
- Department of Biomedical Engineering and Physics, Amsterdam UMC, University of Amsterdam, Cancer Center Amsterdam, Amsterdam, The Netherlands
| | - Mieke T Bus
- Department of Urology, Amsterdam UMC, University of Amsterdam, Cancer Center Amsterdam, Amsterdam, The Netherlands
| | - Ton G van Leeuwen
- Department of Biomedical Engineering and Physics, Amsterdam UMC, University of Amsterdam, Cancer Center Amsterdam, Amsterdam, The Netherlands
| | - Daniel M de Bruin
- Department of Urology, Amsterdam UMC, University of Amsterdam, Cancer Center Amsterdam, Amsterdam, The Netherlands
- Department of Biomedical Engineering and Physics, Amsterdam UMC, University of Amsterdam, Cancer Center Amsterdam, Amsterdam, The Netherlands
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Spectroscopic Optical Coherence Tomography by Using Multiple Multipole Expansion. PHOTONICS 2018. [DOI: 10.3390/photonics5040044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This paper presents a pre-processing method to remove multiple scattering artifacts in spectroscopic optical coherence tomography (SOCT) using time–frequency analysis approaches. The method uses a multiple multipole expansion approach to model the light fields in SOCT. It is shown that the multiple scattered fields can be characterized by higher order terms of the multiple multipole expansion. Hence, the multiple scattering artifact can thus be eliminated by applying the time–frequency transform on the SOCT measurements characterized by the lower order terms. Simulation and experimental results are presented to show the effectiveness of the proposed pre-processing method.
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Rico-Jimenez JJ, Campos-Delgado DU, Villiger M, Otsuka K, Bouma BE, Jo JA. Automatic classification of atherosclerotic plaques imaged with intravascular OCT. BIOMEDICAL OPTICS EXPRESS 2016; 7:4069-4085. [PMID: 27867716 PMCID: PMC5102521 DOI: 10.1364/boe.7.004069] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/09/2016] [Accepted: 09/12/2016] [Indexed: 05/24/2023]
Abstract
Intravascular optical coherence tomography (IV-OCT) allows evaluation of atherosclerotic plaques; however, plaque characterization is performed by visual assessment and requires a trained expert for interpretation of the large data sets. Here, we present a novel computational method for automated IV-OCT plaque characterization. This method is based on the modeling of each A-line of an IV-OCT data set as a linear combination of a number of depth profiles. After estimating these depth profiles by means of an alternating least square optimization strategy, they are automatically classified to predefined tissue types based on their morphological characteristics. The performance of our proposed method was evaluated with IV-OCT scans of cadaveric human coronary arteries and corresponding tissue histopathology. Our results suggest that this methodology allows automated identification of fibrotic and lipid-containing plaques. Moreover, this novel computational method has the potential to enable high throughput atherosclerotic plaque characterization.
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Affiliation(s)
- Jose J. Rico-Jimenez
- Department of Biomedical Engineering, Texas A & M University, College Station, TX,
USA
| | | | - Martin Villiger
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, Boston, MA,
USA
| | - Kenichiro Otsuka
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, Boston, MA,
USA
| | - Brett E. Bouma
- Wellman Center for Photomedicine, Harvard Medical School and Massachusetts General Hospital, Boston, MA,
USA
| | - Javier A. Jo
- Department of Biomedical Engineering, Texas A & M University, College Station, TX,
USA
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