1
|
Yan J, Huang B, Tonko J, Toulemonde M, Hansen-Shearer J, Tan Q, Riemer K, Ntagiantas K, Chowdhury RA, Lambiase PD, Senior R, Tang MX. Transthoracic ultrasound localization microscopy of myocardial vasculature in patients. Nat Biomed Eng 2024:10.1038/s41551-024-01206-6. [PMID: 38710839 DOI: 10.1038/s41551-024-01206-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 03/30/2024] [Indexed: 05/08/2024]
Abstract
Myocardial microvasculature and haemodynamics are indicative of potential microvascular diseases for patients with symptoms of coronary heart disease in the absence of obstructive coronary arteries. However, imaging microvascular structure and flow within the myocardium is challenging owing to the small size of the vessels and the constant movement of the patient's heart. Here we show the feasibility of transthoracic ultrasound localization microscopy for imaging myocardial microvasculature and haemodynamics in explanted pig hearts and in patients in vivo. Through a customized data-acquisition and processing pipeline with a cardiac phased-array probe, we leveraged motion correction and tracking to reconstruct the dynamics of microcirculation. For four patients, two of whom had impaired myocardial function, we obtained super-resolution images of myocardial vascular structure and flow using data acquired within a breath hold. Myocardial ultrasound localization microscopy may facilitate the understanding of myocardial microcirculation and the management of patients with cardiac microvascular diseases.
Collapse
Affiliation(s)
- Jipeng Yan
- Ultrasound Lab for Imaging and Sensing, Department of Bioengineering, Imperial College London, London, UK
| | - Biao Huang
- Ultrasound Lab for Imaging and Sensing, Department of Bioengineering, Imperial College London, London, UK
| | - Johanna Tonko
- Institute of Cardiovascular Science, University College London, London, UK
| | - Matthieu Toulemonde
- Ultrasound Lab for Imaging and Sensing, Department of Bioengineering, Imperial College London, London, UK
| | - Joseph Hansen-Shearer
- Ultrasound Lab for Imaging and Sensing, Department of Bioengineering, Imperial College London, London, UK
| | - Qingyuan Tan
- Ultrasound Lab for Imaging and Sensing, Department of Bioengineering, Imperial College London, London, UK
| | - Kai Riemer
- Ultrasound Lab for Imaging and Sensing, Department of Bioengineering, Imperial College London, London, UK
| | | | - Rasheda A Chowdhury
- Faculty of Medicine, National Heart and Lung Institute, Imperial College London, London, UK
| | - Pier D Lambiase
- Institute of Cardiovascular Science, University College London, London, UK
| | - Roxy Senior
- Faculty of Medicine, National Heart and Lung Institute, Imperial College London, London, UK
- Royal Brompton Hospital, London, UK
- Northwick Park Hospital, Harrow, UK
| | - Meng-Xing Tang
- Ultrasound Lab for Imaging and Sensing, Department of Bioengineering, Imperial College London, London, UK.
| |
Collapse
|
2
|
Bourquin C, Porée J, Rauby B, Perrot V, Ghigo N, Belgharbi H, Bélanger S, Ramos-Palacios G, Cortes N, Ladret H, Ikan L, Casanova C, Lesage F, Provost J. Quantitative pulsatility measurements using 3D dynamic ultrasound localization microscopy. Phys Med Biol 2024; 69:045017. [PMID: 38181421 DOI: 10.1088/1361-6560/ad1b68] [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: 07/17/2023] [Accepted: 01/05/2024] [Indexed: 01/07/2024]
Abstract
A rise in blood flow velocity variations (i.e. pulsatility) in the brain, caused by the stiffening of upstream arteries, is associated with cognitive impairment and neurodegenerative diseases. The study of this phenomenon requires brain-wide pulsatility measurements, with large penetration depth and high spatiotemporal resolution. The development of dynamic ultrasound localization microscopy (DULM), based on ULM, has enabled pulsatility measurements in the rodent brain in 2D. However, 2D imaging accesses only one slice of the brain and measures only 2D-projected and hence biased velocities . Herein, we present 3D DULM: using a single ultrasound scanner at high frame rate (1000-2000 Hz), this method can produce dynamic maps of microbubbles flowing in the bloodstream and extract quantitative pulsatility measurements in the cat brain with craniotomy and in the mouse brain through the skull, showing a wide range of flow hemodynamics in both large and small vessels. We highlighted a decrease in pulsatility along the vascular tree in the cat brain, which could be mapped with ultrasound down to a few tens of micrometers for the first time. We also performed an intra-animal validation of the method by showing consistent measurements between the two sides of the Willis circle in the mouse brain. Our study provides the first step towards a new biomarker that would allow the detection of dynamic abnormalities in microvessels in the brain, which could be linked to early signs of neurodegenerative diseases.
Collapse
Affiliation(s)
- Chloé Bourquin
- Department of Engineering Physics, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada
| | - Jonathan Porée
- Department of Engineering Physics, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada
| | - Brice Rauby
- Department of Engineering Physics, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada
| | - Vincent Perrot
- Department of Engineering Physics, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada
| | - Nin Ghigo
- Department of Engineering Physics, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada
| | - Hatim Belgharbi
- Department of Engineering Physics, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada
- Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC 27599, United States of America
| | | | | | - Nelson Cortes
- School of Optometry, University of Montreal, Montréal, QC H3T 1P1, Canada
| | - Hugo Ladret
- School of Optometry, University of Montreal, Montréal, QC H3T 1P1, Canada
- Institut de Neurosciences de la Timone, UMR 7289, CNRS and Aix-Marseille Université, Marseille, F-13005, France
| | - Lamyae Ikan
- School of Optometry, University of Montreal, Montréal, QC H3T 1P1, Canada
| | - Christian Casanova
- School of Optometry, University of Montreal, Montréal, QC H3T 1P1, Canada
| | - Frédéric Lesage
- Department of Electrical Engineering, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada
- Montreal Heart Institute, Montréal, QC H1T 1C8, Canada
| | - Jean Provost
- Department of Engineering Physics, Polytechnique Montréal, Montréal, QC H3T 1J4, Canada
- Montreal Heart Institute, Montréal, QC H1T 1C8, Canada
| |
Collapse
|
3
|
Søgaard SB, Andersen SB, Taghavi I, Schou M, Christoffersen C, Jacobsen JCB, Kjer HM, Gundlach C, McDermott A, Jensen JA, Nielsen MB, Sørensen CM. Super-Resolution Ultrasound Imaging of Renal Vascular Alterations in Zucker Diabetic Fatty Rats during the Development of Diabetic Kidney Disease. Diagnostics (Basel) 2023; 13:3197. [PMID: 37892017 PMCID: PMC10605617 DOI: 10.3390/diagnostics13203197] [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: 09/03/2023] [Revised: 10/08/2023] [Accepted: 10/11/2023] [Indexed: 10/29/2023] Open
Abstract
Individuals with diabetes at risk of developing diabetic kidney disease (DKD) are challenging to identify using currently available clinical methods. Prognostic accuracy and initiation of treatment could be improved by a quantification of the renal microvascular rarefaction and the increased vascular tortuosity during the development of DKD. Super-resolution ultrasound (SRUS) imaging is an in vivo technique capable of visualizing blood vessels at sizes below 75 µm. This preclinical study aimed to investigate the alterations in renal blood vessels' density and tortuosity in a type 2 diabetes rat model, Zucker diabetic fatty (ZDF) rats, as a prediction of DKD. Lean age-matched Zucker rats were used as controls. A total of 36 rats were studied, subdivided into ages of 12, 22, and 40 weeks. Measured albuminuria indicated the early stage of DKD, and the SRUS was compared with the ex vivo micro-computed tomography (µCT) of the same kidneys. Assessed using the SRUS imaging, a significantly decreased cortical vascular density was detected in the ZDF rats from 22 weeks of age compared to the healthy controls, concomitant with a significantly increased albuminuria. Already by week 12, a trend towards a decreased cortical vascular density was found prior to the increased albuminuria. The quantified vascular density in µCT corresponded with the in vivo SRUS imaging, presenting a consistently lower vascular density in the ZDF rats. Regarding vessel tortuosity, an overall trend towards an increased tortuosity was present in the ZDF rats. SRUS shows promise for becoming an additional tool for monitoring and prognosing DKD. In the future, large-scale animal studies and human trials are needed for confirmation.
Collapse
Affiliation(s)
- Stinne Byrholdt Søgaard
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; (S.B.S.); (S.B.A.); (C.C.); (J.C.B.J.); (A.M.)
- Department of Diagnostic Radiology, Rigshospitalet, 2100 Copenhagen, Denmark;
| | - Sofie Bech Andersen
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; (S.B.S.); (S.B.A.); (C.C.); (J.C.B.J.); (A.M.)
- Department of Diagnostic Radiology, Rigshospitalet, 2100 Copenhagen, Denmark;
| | - Iman Taghavi
- Center for Fast Ultrasound Imaging, Department of Health Technology, Technical University of Denmark, 2800 Lyngby, Denmark; (I.T.); (J.A.J.)
| | | | - Christina Christoffersen
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; (S.B.S.); (S.B.A.); (C.C.); (J.C.B.J.); (A.M.)
- Department of Clinical Biochemistry, Rigshospitalet, 2100 Copenhagen, Denmark
| | - Jens Christian Brings Jacobsen
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; (S.B.S.); (S.B.A.); (C.C.); (J.C.B.J.); (A.M.)
| | - Hans Martin Kjer
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800 Lyngby, Denmark;
| | - Carsten Gundlach
- Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark;
| | - Amy McDermott
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; (S.B.S.); (S.B.A.); (C.C.); (J.C.B.J.); (A.M.)
| | - Jørgen Arendt Jensen
- Center for Fast Ultrasound Imaging, Department of Health Technology, Technical University of Denmark, 2800 Lyngby, Denmark; (I.T.); (J.A.J.)
| | - Michael Bachmann Nielsen
- Department of Diagnostic Radiology, Rigshospitalet, 2100 Copenhagen, Denmark;
- Department of Clinical Medicine, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Charlotte Mehlin Sørensen
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; (S.B.S.); (S.B.A.); (C.C.); (J.C.B.J.); (A.M.)
| |
Collapse
|
4
|
Dencks S, Schmitz G. Ultrasound localization microscopy. Z Med Phys 2023; 33:292-308. [PMID: 37328329 PMCID: PMC10517400 DOI: 10.1016/j.zemedi.2023.02.004] [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: 08/11/2022] [Revised: 01/24/2023] [Accepted: 02/10/2023] [Indexed: 06/18/2023]
Abstract
Ultrasound Localization Microscopy (ULM) is an emerging technique that provides impressive super-resolved images of microvasculature, i.e., images with much better resolution than the conventional diffraction-limited ultrasound techniques and is already taking its first steps from preclinical to clinical applications. In comparison to the established perfusion or flow measurement methods, namely contrast-enhanced ultrasound (CEUS) and Doppler techniques, ULM allows imaging and flow measurements even down to the capillary level. As ULM can be realized as a post-processing method, conventional ultrasound systems can be used for. ULM relies on the localization of single microbubbles (MB) of commercial, clinically approved contrast agents. In general, these very small and strong scatterers with typical radii of 1-3 µm are imaged much larger in ultrasound images than they actually are due to the point spread function of the imaging system. However, by applying appropriate methods, these MBs can be localized with sub-pixel precision. Then, by tracking MBs over successive frames of image sequences, not only the morphology of vascular trees but also functional information such as flow velocities or directions can be obtained and visualized. In addition, quantitative parameters can be derived to describe pathological and physiological changes in the microvasculature. In this review, the general concept of ULM and conditions for its applicability to microvessel imaging are explained. Based on this, various aspects of the different processing steps for a concrete implementation are discussed. The trade-off between complete reconstruction of the microvasculature and the necessary measurement time as well as the implementation in 3D are reviewed in more detail, as they are the focus of current research. Through an overview of potential or already realized preclinical and clinical applications - pathologic angiogenesis or degeneration of vessels, physiological angiogenesis, or the general understanding of organ or tissue function - the great potential of ULM is demonstrated.
Collapse
Affiliation(s)
- Stefanie Dencks
- Lehrstuhl für Medizintechnik, Fakultät für Elektrotechnik und Informationstechnik, Ruhr-Universität Bochum, Bochum, Germany.
| | - Georg Schmitz
- Lehrstuhl für Medizintechnik, Fakultät für Elektrotechnik und Informationstechnik, Ruhr-Universität Bochum, Bochum, Germany
| |
Collapse
|
5
|
Lei S, Zhang C, Zhu B, Gao Z, Zhang Q, Liu J, Li Y, Zheng H, Ma T. In vivo ocular microvasculature imaging in rabbits with 3D ultrasound localization microscopy. ULTRASONICS 2023; 133:107022. [PMID: 37178486 DOI: 10.1016/j.ultras.2023.107022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 04/15/2023] [Accepted: 04/19/2023] [Indexed: 05/15/2023]
Abstract
Morphological and hemodynamic changes in the ocular vasculature are important signs of various ocular diseases. The evaluation of the ocular microvasculature with high resolution is valuable in comprehensive diagnoses. However, it is difficult for current optical imaging techniques to visualize the posterior segment and retrobulbar microvasculature due to the limited penetration depth of light, particularly when the refractive medium is opaque. Thus, we have developed a 3D ultrasound localization microscopy (ULM) imaging method to visualize the ocular microvasculature in rabbits with micron-scale resolution. We used a 32 × 32 matrix array transducer (center frequency: 8 MHz) with a compounding plane wave sequence and microbubbles. Block-wise singular value decomposition spatiotemporal clutter filtering and block-matching 3D denoising were implemented to extract the flowing microbubble signals at different imaging depths with high signal-to-noise ratios. The center points of microbubbles were localized and tracked in 3D space to achieve the micro-angiography. The in vivo results demonstrate the ability of 3D ULM to visualize the microvasculature of the eye in rabbits, where vessels down to 54 μm were successfully revealed. Moreover, the microvascular maps indicated the morphological abnormalities in the eye with retinal detachment. This efficient modality shows potential for use in the diagnosis of ocular diseases.
Collapse
Affiliation(s)
- Shuang Lei
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China; Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Changlu Zhang
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Benpeng Zhu
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China.
| | - Zeping Gao
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Qi Zhang
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China; National Innovation Center for Advanced Medical Devices, Shenzhen 518126, China
| | - Jiamei Liu
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China; National Innovation Center for Advanced Medical Devices, Shenzhen 518126, China
| | - Yongchuan Li
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Hairong Zheng
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Teng Ma
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China; National Innovation Center for Advanced Medical Devices, Shenzhen 518126, China.
| |
Collapse
|
6
|
Søgaard SB, Andersen SB, Taghavi I, Hoyos CAV, Christoffersen C, Hansen KL, Jensen JA, Nielsen MB, Sørensen CM. Super-Resolution Ultrasound Imaging Provides Quantification of the Renal Cortical and Medullary Vasculature in Obese Zucker Rats: A Pilot Study. Diagnostics (Basel) 2022; 12:diagnostics12071626. [PMID: 35885531 PMCID: PMC9318608 DOI: 10.3390/diagnostics12071626] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 06/17/2022] [Accepted: 07/01/2022] [Indexed: 11/16/2022] Open
Abstract
Obesity is a risk factor of chronic kidney disease (CKD), leading to alterations in the renal vascular structure. This study tested if renal vascular density and tortuosity was quantifiable in vivo in obese rats using microbubble-based super-resolution ultrasound imaging. The kidneys of two 11-week-old and two 20-week-old male obese Zucker rats were compared with age-matched male lean Zucker rats. The super-resolution ultrasound images were manually divided into inner medulla, outer medulla, and cortex, and each area was subdivided into arteries and veins. We quantified vascular density and tortuosity, number of detected microbubbles, and generated tracks. For comparison, we assessed glomerular filtration rate, albumin/creatinine ratio, and renal histology to evaluate CKD. The number of detected microbubbles and generated tracks varied between animals and significantly affected quantification of vessel density. In areas with a comparable number of tracks, density increased in the obese animals, concomitant with a decrease in glomerular filtration rate and an increase in albumin/creatinine ratio, but without any pathology in the histological staining. The results indicate that super-resolution ultrasound imaging can be used to quantify structural alterations in the renal vasculature. Techniques to generate more comparable number of microbubble tracks and confirmation of the findings in larger-scale studies are needed.
Collapse
Affiliation(s)
- Stinne Byrholdt Søgaard
- Department of Diagnostic Radiology, Rigshospitalet, 2100 Copenhagen, Denmark; (S.B.A.); (K.L.H.); (M.B.N.)
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; (C.C.); (C.M.S.)
- Department of Clinical Medicine, University of Copenhagen, 2200 Copenhagen, Denmark
- Correspondence:
| | - Sofie Bech Andersen
- Department of Diagnostic Radiology, Rigshospitalet, 2100 Copenhagen, Denmark; (S.B.A.); (K.L.H.); (M.B.N.)
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; (C.C.); (C.M.S.)
| | - Iman Taghavi
- Center for Fast Ultrasound Imaging, Department of Health Technology, Technical University of Denmark, 2800 Lyngby, Denmark; (I.T.); (J.A.J.)
| | | | - Christina Christoffersen
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; (C.C.); (C.M.S.)
- Department of Clinical Biochemistry, Rigshospitalet, 2100 Copenhagen, Denmark
| | - Kristoffer Lindskov Hansen
- Department of Diagnostic Radiology, Rigshospitalet, 2100 Copenhagen, Denmark; (S.B.A.); (K.L.H.); (M.B.N.)
- Department of Clinical Medicine, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Jørgen Arendt Jensen
- Center for Fast Ultrasound Imaging, Department of Health Technology, Technical University of Denmark, 2800 Lyngby, Denmark; (I.T.); (J.A.J.)
| | - Michael Bachmann Nielsen
- Department of Diagnostic Radiology, Rigshospitalet, 2100 Copenhagen, Denmark; (S.B.A.); (K.L.H.); (M.B.N.)
- Department of Clinical Medicine, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Charlotte Mehlin Sørensen
- Department of Biomedical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; (C.C.); (C.M.S.)
| |
Collapse
|
7
|
Ultrasound Localization Microscopy in Liquid Metal Flows. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12094517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Liquid metal convection plays an important role in natural and technical processes. In experimental studies, an instrumentation with a sub-millimeter spatial resolution is required in an opaque fluid to resolve the flow field near the boundary layer. Using ultrasound methods, the trade-off between the frequency and imaging depth of typical laboratory experiments limits the spatial resolution. Therefore, the method of ultrasound localization microscopy (ULM) was introduced in liquid metal experiments for the first time in this study. To isolate the intrinsic scattering particles, an adaptive nonlinear beamformer was applied. As a result, an average spatial resolution of 188 μm could be achieved, which corresponded to a fraction of the ultrasound wavelength of 0.28. A convection experiment was measured using ULM. Due to the increased spatial resolution, the high-velocity gradients and the recirculation areas of a liquid metal convection experiment could be observed for the first time. The presented technique paves the way for in-depth flow studies of convective turbulent liquid metal flows that are close to the boundary layer.
Collapse
|
8
|
Super-Resolution Ultrasound Imaging Can Quantify Alterations in Microbubble Velocities in the Renal Vasculature of Rats. Diagnostics (Basel) 2022; 12:diagnostics12051111. [PMID: 35626267 PMCID: PMC9140053 DOI: 10.3390/diagnostics12051111] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 04/04/2022] [Accepted: 04/27/2022] [Indexed: 11/17/2022] Open
Abstract
Super-resolution ultrasound imaging, based on the localization and tracking of single intravascular microbubbles, makes it possible to map vessels below 100 µm. Microbubble velocities can be estimated as a surrogate for blood velocity, but their clinical potential is unclear. We investigated if a decrease in microbubble velocity in the arterial and venous beds of the renal cortex, outer medulla, and inner medulla was detectable after intravenous administration of the α1-adrenoceptor antagonist prazosin. The left kidneys of seven rats were scanned with super-resolution ultrasound for 10 min before, during, and after prazosin administration using a bk5000 ultrasound scanner and hockey-stick probe. The super-resolution images were manually segmented, separating cortex, outer medulla, and inner medulla. Microbubble tracks from arteries/arterioles were separated from vein/venule tracks using the arterial blood flow direction. The mean microbubble velocities from each scan were compared. This showed a significant prazosin-induced velocity decrease only in the cortical arteries/arterioles (from 1.59 ± 0.38 to 1.14 ± 0.31 to 1.18 ± 0.33 mm/s, p = 0.013) and outer medulla descending vasa recta (from 0.70 ± 0.05 to 0.66 ± 0.04 to 0.69 ± 0.06 mm/s, p = 0.026). Conclusively, super-resolution ultrasound imaging makes it possible to detect and differentiate microbubble velocity responses to prazosin simultaneously in the renal cortical and medullary vascular beds.
Collapse
|