scholarly journals Improved Ultrasound Localization Microscopy based on Microbubble Uncoupling via Transmit Excitation (MUTE)

2021 ◽  
Author(s):  
Jihun Kim ◽  
Mathew R. Lowerison ◽  
Nathiya Chandra Sekaran ◽  
Zhengchang Kou ◽  
Zhijie Dong ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Chorioallantoic Membrane ◽  
Super Resolution ◽  
Stimulated Emission ◽  
Acquisition Time ◽  
Localization Microscopy ◽  
Ultrasound Localization ◽  
Robust Localization ◽  
Data Acquisition Time

AbstractUltrasound localization microscopy (ULM) demonstrates great potential for visualization of tissue microvasculature at depth with high spatial resolution. The success of ULM heavily depends on the robust localization of isolated microbubbles (MBs), which can be challenging in vivo especially within larger vessels where MBs can overlap and cluster close together. While MB dilution alleviates the issue of MB overlap to a certain extent, it drastically increases the data acquisition time needed for MBs to populate the microvasculature, which is already on the order of several minutes using recommended MB concentrations. Inspired by optical super-resolution imaging based on stimulated emission depletion (STED), here we propose a novel ULM imaging sequence based on microbubble uncoupling via transmit excitation (MUTE). MUTE “silences” MB signals by creating acoustic nulls to facilitate MB separation, which leads to robust localization of MBs especially under high concentrations. The efficiency of localization accomplished via the proposed technique was first evaluated in simulation studies with conventional ULM as a benchmark. Then an in vivo study based on the chorioallantoic membrane (CAM) of chicken embryos showed that MUTE could reduce the data acquisition time by half thanks to the enhanced MB separation and localization. Finally, the performance of MUTE was validated in an in vivo mouse brain study. These results demonstrate the high MB localization efficacy of MUTE-ULM, which contributes to a reduced data acquisition time and improved temporal resolution for ULM.

scholarly journals An Anatomically and Hemodynamically Realistic Simulation Framework for 3D Ultrasound Localization Microscopy

2021 ◽  
Author(s):  
Hatim Belgharbi ◽  
Jonathan Poree ◽  
Rafat Damseh ◽  
Vincent Perrot ◽  
Patrick Delafontaine-Martel ◽  
...  
Keyword(s):  
3D Ultrasound ◽  
Acquisition Time ◽  
Simulation Framework ◽  
Low Frequencies ◽  
Localization Microscopy ◽  
Two Photon Microscopy ◽  
Ultrasound Localization ◽  
Two Photon ◽  
Wavelength Resolution

The resolution of 3D Ultrasound Localization Microscopy (ULM) is determined by acquisition parameters such as frequency and transducer geometry but also by microbubble (MB) concentration, which is also linked to the total acquisition time needed to sample the vascular tree at different scales. In this study, we introduce a novel 3D anatomically- and physiologically-realistic ULM simulation framework based on two-photon microscopy (2PM) and in-vivo MB perfusion dynamics. As a proof of concept, using metrics such as MB localization error, MB count and network filling, we could quantify the effect of MB concentration and PSF volume by varying probe transmit frequency (3-15 MHz). We find that while low frequencies can achieve sub-wavelength resolution as predicted by theory, they are also associated with prolonged acquisition times to map smaller vessels, thus limiting effective resolution. A linear relationship was found between maximal MB concentration and inverse point spread function (PSF) volume. Since inverse PSF volume roughly scales cubically with frequency, the reconstruction of the equivalent of 10 minutes at 15 MHz would require hours at 3 MHz. We expect that these findings can be leveraged to achieve effective reconstruction and serve as a guide for choosing optimal MB concentrations in ULM.

scholarly journals Aging-related cerebral microvascular changes visualized using ultrasound localization microscopy in the living mouse

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Matthew R. Lowerison ◽  
Nathiya Vaithiyalingam Chandra Sekaran ◽  
Wei Zhang ◽  
Zhijie Dong ◽  
Xi Chen ◽  
...  
Keyword(s):  
Cognitive Decline ◽  
Super Resolution ◽  
Brain Regions ◽  
Blood Velocity ◽  
Aging Brain ◽  
Health Crisis ◽  
Localization Microscopy ◽  
Ultrasound Localization ◽  
Microvascular Changes

AbstractAging-related cognitive decline is an emerging health crisis; however, no established unifying mechanism has been identified for the cognitive impairments seen in an aging population. A vascular hypothesis of cognitive decline has been proposed but is difficult to test given the requirement of high-fidelity microvascular imaging resolution with a broad and deep brain imaging field of view, which is restricted by the fundamental trade-off of imaging penetration depth and resolution. Super-resolution ultrasound localization microscopy (ULM) offers a potential solution by exploiting circulating microbubbles to achieve a vascular resolution approaching the capillary scale without sacrificing imaging depth. In this report, we apply ULM imaging to a mouse model of aging and quantify differences in cerebral vascularity, blood velocity, and vessel tortuosity across several brain regions. We found significant decreases in blood velocity, and significant increases in vascular tortuosity, across all brain regions in the aged cohort, and significant decreases in blood volume in the cerebral cortex. These data provide the first-ever ULM measurements of subcortical microvascular dynamics in vivo within the context of the aging brain and reveal that aging has a major impact on these measurements.

INFLUENCE OF LIMITED-PROJECTION ON FLUORESCENCE MOLECULAR TOMOGRAPHY

2012 ◽  
Vol 05 (03) ◽  
pp. 1250020 ◽  
Author(s):  
YUN HE ◽  
XU CAO ◽  
FEI LIU ◽  
JIANWEN LUO ◽  
JING BAI
Keyword(s):  
Data Acquisition ◽  
Systematic Investigation ◽  
Acquisition Time ◽  
Projection Data ◽  
Fluorescence Molecular Tomography ◽  
Time Data ◽  
Phantom Experiment ◽  
Reconstruction Quality ◽  
Data Acquisition Time

Challenges remain in imaging fast biological processes in vivo with fluorescence molecular tomography (FMT) due to the long data acquisition time. Data acquisition with limited projections can greatly reduce the time consumption, but the influence of limited-projection on reconstruction quality is currently unclear. Both numerical simulations and a phantom experiment are conducted to analyze this problem. Through a systematic investigation of all the results reconstructed from different numbers of projections, we evaluate the influence of limited-projection data on FMT. A mouse experiment is also performed to validate our work. A general relationship between the number of projections and reconstruction quality is obtained which indicates that the projection number of three is preferred for fast FMT experiment.

scholarly journals Aging-related cerebral microvascular changes visualized using Ultrasound Localization Microscopy in the living mouse

2021 ◽  
Author(s):  
Matthew R Lowerison ◽  
Nathiya Chandra Sekaran ◽  
Wei Zhang ◽  
Zhijie Dong ◽  
Xi Chen ◽  
...  
Keyword(s):  
Cognitive Decline ◽  
Super Resolution ◽  
Brain Regions ◽  
Blood Velocity ◽  
Health Crisis ◽  
Localization Microscopy ◽  
Ultrasound Localization ◽  
Microvascular Changes ◽  
Living Mouse

Aging-related cognitive decline is an emerging health crisis; however, no established unifying mechanism has been identified for the cognitive impairments seen in an aging population. A vascular hypothesis of cognitive decline has been proposed but is difficult to test given the contradictory radiologic needs of high-fidelity microvascular imaging resolution and a broad and deep brain imaging field of view. Super-resolution ultrasound localization microscopy (ULM) offers a potential solution by exploiting circulating microbubbles to achieve a vascular resolution approaching the capillary scale without sacrificing imaging depth. In this report, we apply ULM imaging to a mouse model of aging and quantify differences in cerebral vascularity, blood velocity, and vessel tortuosity across several brain regions. We found significant decreases in blood velocity, and significant increases in vascular tortuosity, across all brain regions in the aged cohort, and significant decreases in blood volume in the cortex. These data provide the first-ever measurements of subcortical microvascular dynamics in vivo and reveal that aging has a major impact on these measurements.

scholarly journals Novel strategy for measuring creatine kinase reaction rate in the in vivo heart

2009 ◽  
Vol 297 (3) ◽  
pp. H1010-H1019 ◽  
Author(s):  
Qiang Xiong ◽  
Qinglu Li ◽  
Abdul Mansoor ◽  
Mohammad Nurulqadr Jameel ◽  
Fei Du ◽  
...  
Keyword(s):  
Creatine Kinase ◽  
Data Acquisition ◽  
Rate Constant ◽  
Order Rate Constant ◽  
Acquisition Time ◽  
Atp Production ◽  
First Order ◽  
Data Acquisition Time ◽  
Pseudo First Order

In the heart, the creatine kinase (CK) system plays an important role in the cascade of ATP production, transportation, and utilization. The forward pseudo-first-order rate constant for the CK reaction can be measured noninvasively by the 31P-magnetic resonance (MR) spectroscopy magnetization saturation transfer (MST) techniques. However, the measurement of MST in the in vivo heart is limited by the lengthy data acquisition time, especially for studies requiring spatial localization. This technical report presents a new method for measuring ATP production rate via CK that can reduce the MST data acquisition time by 82%. This method is validated using an in vivo pig model to evaluate the forward pseudo-first-order rate constant of myocardial CK reaction noninvasively.

scholarly journals Comparing Super-Resolution Microscopy Techniques to Analyze Chromosomes

2021 ◽  
Vol 22 (4) ◽  
pp. 1903
Author(s):  
Ivona Kubalová ◽  
Alžběta Němečková ◽  
Klaus Weisshart ◽  
Eva Hřibová ◽  
Veit Schubert
Keyword(s):  
Single Molecule ◽  
Imaging Techniques ◽  
Chromatin Condensation ◽  
Super Resolution ◽  
Stimulated Emission ◽  
Wide Field ◽  
Structured Illumination Microscopy ◽  
Metaphase Chromosomes ◽  
Localization Microscopy ◽  
Super Resolution Microscopy

The importance of fluorescence light microscopy for understanding cellular and sub-cellular structures and functions is undeniable. However, the resolution is limited by light diffraction (~200–250 nm laterally, ~500–700 nm axially). Meanwhile, super-resolution microscopy, such as structured illumination microscopy (SIM), is being applied more and more to overcome this restriction. Instead, super-resolution by stimulated emission depletion (STED) microscopy achieving a resolution of ~50 nm laterally and ~130 nm axially has not yet frequently been applied in plant cell research due to the required specific sample preparation and stable dye staining. Single-molecule localization microscopy (SMLM) including photoactivated localization microscopy (PALM) has not yet been widely used, although this nanoscopic technique allows even the detection of single molecules. In this study, we compared protein imaging within metaphase chromosomes of barley via conventional wide-field and confocal microscopy, and the sub-diffraction methods SIM, STED, and SMLM. The chromosomes were labeled by DAPI (4′,6-diamidino-2-phenylindol), a DNA-specific dye, and with antibodies against topoisomerase IIα (Topo II), a protein important for correct chromatin condensation. Compared to the diffraction-limited methods, the combination of the three different super-resolution imaging techniques delivered tremendous additional insights into the plant chromosome architecture through the achieved increased resolution.

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