Ultrafast amplitude modulation for molecular and hemodynamic ultrasound imaging

Ultrasound is playing an emerging role in molecular and cellular imaging thanks to new micro- and nanoscale contrast agents and reporter genes. Acoustic methods for the selective in vivo detection of these imaging agents are needed to maximize their impact in biology and medicine. Existing ultrasound pulse sequences use the nonlinearity in contrast agents response to acoustic pressure to distinguish them from mostly linear tissue scattering. However, such pulse sequences typically scan the sample using focused transmissions, resulting in a limited frame rate and restricted field of view. Meanwhile, existing wide-field scanning techniques based on plane wave transmissions suffer from limited sensitivity or nonlinear artifacts. To overcome these limitations, we introduce an ultrafast nonlinear imaging modality combining amplitude-modulated pulses, multiplane wave transmissions and selective coherent compounding. This technique achieves contrast imaging sensitivity comparable to much slower gold-standard amplitude modulation sequences and enables the acquisition of larger and deeper fields of view, while providing a much faster imaging framerate of 3.2kHz. Additionally, it enables simultaneous nonlinear and linear image formation, and allows concurrent monitoring of phenomena accessible only at ultrafast framerates, such as blood volume variations. We demonstrate the performance of this ultrafast amplitude modulation (uAM) technique by imaging gas vesicles, an emerging class of genetically encodable biomolecular contrast agents, in several in vitro and in vivo contexts. These demonstrations include the rapid discrimination of moving contrast agents and the real-time monitoring of phagolysosomal function in the mouse liver.

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Real-Time Excitation-Enhanced Ultrasound Contrast Imaging

Ultrasonic Imaging ◽

10.1177/016173460502700201 ◽

2005 ◽

Vol 27 (2) ◽

pp. 65-74 ◽

Cited By ~ 2

Author(s):

Flemming Forsberg ◽

William T. Shi ◽

Michael K. Knauer ◽

Anne L. Hall ◽

Chris Vecchio ◽

...

Keyword(s):

Real Time ◽

Imaging Modality ◽

Surrounding Tissue ◽

Contrast Imaging ◽

Maximum Enhancement ◽

Ultrasound Contrast ◽

Ultrasound Contrast Imaging ◽

Contrast Microbubbles

A new nonlinear contrast specific imaging modality, excitation-enhanced imaging (EEI) has been implemented on commercially-available scanners for real-time imaging. This novel technique employs two acoustic fields: a low-frequency, high-intensity ultrasound field (the excitation field) to actively condition contrast microbubbles, and a second lower-intensity regular imaging field applied shortly afterwards to detect enhanced contrast scattering. A Logiq 9 scanner (GE Healthcare, Milwaukee, WI) with a 3.5C curved linear array and an AN2300 digital ultrasound engine (Analogic Corporation, Peabody, MA) with a P4-2 phased array transducer (Philips Medical Systems, Bothell, WA) were modified to perform EEI on a vector-by-vector basis in fundamental and pulse inversion harmonic grayscale modes. Ultrasound contrast microbubbles within an 8 mm vessel embedded in a tissue-mimicking flow phantom (ATS Laboratories, Bridgeport, CT) were imaged in vitro. While video intensities of scattered signals from the surrounding tissue were unchanged, video intensities of echoes from contrast bubbles within the vessel were markedly enhanced. The maximum enhancement achieved was 10.4 dB in harmonic mode (mean enhancement: 6.3 dB; p=0.0007). In conclusion, EEI may improve the sensitivity of ultrasound contrast imaging, but further work is required to assess the in vivo potential of this new technique.

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Ultrasound-Based Molecular Imaging of Tumors with PTPmu Biomarker-Targeted Nanobubble Contrast Agents

International Journal of Molecular Sciences ◽

10.3390/ijms22041983 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1983

Author(s):

Mette L. Johansen ◽

Reshani Perera ◽

Eric Abenojar ◽

Xinning Wang ◽

Jason Vincent ◽

...

Keyword(s):

Contrast Agents ◽

Ultrasound Imaging ◽

Imaging Modality ◽

Tyrosine Phosphatase ◽

Receptor Protein ◽

Contrast Enhanced Ultrasound ◽

Core Lipid ◽

Contrast Enhanced

Ultrasound imaging is a widely used, readily accessible and safe imaging modality. Molecularly-targeted microbubble- and nanobubble-based contrast agents used in conjunction with ultrasound imaging expand the utility of this modality by specifically targeting and detecting biomarkers associated with different pathologies including cancer. In this study, nanobubbles directed to a cancer biomarker derived from the Receptor Protein Tyrosine Phosphatase mu, PTPmu, were evaluated alongside non-targeted nanobubbles using contrast enhanced ultrasound both in vitro and in vivo in mice. In vitro resonant mass and clinical ultrasound measurements showed gas-core, lipid-shelled nanobubbles conjugated to either a PTPmu-directed peptide or a Scrambled control peptide were equivalent. Mice with heterotopic human tumors expressing the PTPmu-biomarker were injected with PTPmu-targeted or control nanobubbles and dynamic contrast-enhanced ultrasound was performed. Tumor enhancement was more rapid and greater with PTPmu-targeted nanobubbles compared to the non-targeted control nanobubbles. Peak tumor enhancement by the PTPmu-targeted nanobubbles occurred within five minutes of contrast injection and was more than 35% higher than the Scrambled nanobubble signal for the subsequent two minutes. At later time points, the signal in tumors remained higher with PTPmu-targeted nanobubbles demonstrating that PTPmu-targeted nanobubbles recognize tumors using molecular ultrasound imaging and may be useful for diagnostic and therapeutic purposes.

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Ultrafast Doppler Reveals the Mapping of Cerebral Vascular Resistivity in Neonates

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2014.49 ◽

2014 ◽

Vol 34 (6) ◽

pp. 1009-1017 ◽

Cited By ~ 36

Author(s):

Charlie Demené ◽

Mathieu Pernot ◽

Valérie Biran ◽

Marianne Alison ◽

Mathias Fink ◽

...

Keyword(s):

Imaging Modality ◽

High Sensitivity ◽

Frame Rate ◽

Doppler Imaging ◽

Whole Body ◽

Simultaneous Estimation ◽

Wide Field ◽

Whole Body Cooling ◽

2D Resistivity

In vivo mapping of the full vasculature dynamics based on Ultrafast Doppler is showed noninvasively in the challenging case of the neonatal brain. Contrary to conventional pulsed-wave (PW) Doppler Ultrasound limited for >40 years to the estimation of vascular indices at a single location, the ultrafast frame rate (5,000 Hz) obtained using plane-wave transmissions leads to simultaneous estimation of full Doppler spectra in all pixels of wide field-of-view images within a single cardiac cycle and high sensitivity Doppler imaging. Consequently, 2D quantitative maps of the cerebro-vascular resistivity index (RI) are processed and found in agreement with local measurements obtained on large arteries of healthy neonates using conventional PW Doppler. Changes in 2D resistivity maps are monitored during recovery after therapeutic whole-body cooling of full-term neonates treated for hypoxic ischemic encephalopathy. Arterial and venous vessels are unambiguously differentiated on the basis of their distinct hemodynamics. The high spatial (250 × 250 μm2) and temporal resolution (<1 ms) of Ultrafast Doppler imaging combined with deep tissue penetration enable precise quantitative mapping of deep brain vascular dynamics and RI, which is far beyond the capabilities of any other imaging modality.

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Tantalum Oxide Nanoparticles as Versatile Contrast Agents for X-ray Computed Tomography

10.26434/chemrxiv.11845572.v1 ◽

2020 ◽

Author(s):

Shatadru Chakravarty ◽

Jeremy Hix ◽

Kaitlyn Wieweora ◽

Maximilian Volk ◽

Elizabeth Kenyon ◽

...

Keyword(s):

Computed Tomography ◽

Contrast Agents ◽

Mesoporous Silica Nanoparticles ◽

Sol Gel ◽

Tantalum Oxide ◽

High Signal ◽

Drug Delivery Vehicles ◽

X Ray Computed

Here we describe the synthesis, characterization and in vitro and in vivo performance of a series of tantalum oxide (TaOx) based nanoparticles (NPs) for computed tomography (CT). Five distinct versions of 9-12 nm diameter silane coated TaOx nanocrystals (NCs) were fabricated by a sol-gel method with varying degrees of hydrophilicity and with or without fluorescence, with the highest reported Ta content to date (78%). Highly hydrophilic NCs were left bare and were evaluated in vivo in mice for micro-CT of full body vasculature, where following intravenous injection, TaOx NCs demonstrate high CT contrast, circulation in blood for ~ 3 h, and eventual accumulation in RES organs; and following injection locally in the mammary gland, where the full ductal tree structure can be clearly delineated. Partially hydrophilic NCs were encapsulated within mesoporous silica nanoparticles (MSNPs; TaOx@MSNPs) and hydrophobic NCs were encapsulated within poly(lactic-co-glycolic acid) (PLGA; TaOx@PLGA) NPs, serving as potential CT-imagable drug delivery vehicles. Bolus intramuscular injections of TaOx@PLGA NPs and TaOx@MSNPs to mimic the accumulation of NPs at a tumor site produce high signal enhancement in mice. In vitro studies on bare NCs and formuated NPs demonstrate high cytocompatibility and low dissolution of TaOx. This work solidifies that TaOx-based NPs are versatile contrast agents for CT.

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Study on Establishing Reference Safe Concentrations of MRI Contrast Agents for Optimized Images: Paramagnetic Gd-DTPA-BMEA and Superparamagnetic Ferucarbotran

Applied Sciences ◽

10.3390/app11031165 ◽

2021 ◽

Vol 11 (3) ◽

pp. 1165

Author(s):

Wen-Tien Hsiao ◽

Yi-Hong Chou ◽

Jhong-Wei Tu ◽

Ai-Yih Wang ◽

Lu-Han Lai

Keyword(s):

Contrast Agent ◽

Contrast Agents ◽

Mri Contrast Agents ◽

Mri Contrast Agent ◽

In Vitro Experiments ◽

Mri Contrast ◽

In Vivo Experiments ◽

Contrast Agent Injection

The purpose of this study is to establish the minimal injection doses of magnetic resonance imaging (MRI) contrast agents that can achieve optimized images while improving the safety of injectable MRI drugs. Gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA) and ferucarbotran, commonly used in clinical practice, were selected and evaluated with in vitro and in vivo experiments. MRI was acquired using T1-weighted (T1W) and T2-weighted (T2W) sequences, and the results were quantitatively analyzed. For in vitro experiments, results showed that T1W and T2W images were optimal when Gd-DTPA-bisamide (2-oxoethyl) (Gd-DTPA-BMEA) and ferucarbotran were diluted to a volume percentage of 0.6% and 0.05%; all comparisons were significant differences in grayscale statistics using one-way analysis of variance (ANOVA). For in vivo experiments, the contrast agent with optimal concentration percentages determined from in vitro experiments were injected into mice with an injection volume of 100 μL, and the images of brain, heart, liver, and mesentery before and after injection were compared. The statistical results showed that the p values of both T1W and T2W were less than 0.001, which were statistically significant. Under safety considerations for MRI contrast agent injection, optimized MRI images could still be obtained after reducing the injection concentration, which can provide a reference for the safety concentrations of MRI contrast agent injection in the future.

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Distinct roles of tumor associated mutations in collective cell migration

Scientific Reports ◽

10.1038/s41598-021-89130-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Rachel M. Lee ◽

Michele I. Vitolo ◽

Wolfgang Losert ◽

Stuart S. Martin

Keyword(s):

Collective Behavior ◽

Metastatic Potential ◽

Breast Epithelial Cell ◽

Collective Cell Migration ◽

Label Free ◽

Collective Migration ◽

Contrast Imaging ◽

Pten Deletion

AbstractRecent evidence suggests that groups of cells are more likely to form clinically dangerous metastatic tumors, emphasizing the importance of understanding mechanisms underlying collective behavior. The emergent collective behavior of migrating cell sheets in vitro has been shown to be disrupted in tumorigenic cells but the connection between this behavior and in vivo tumorigenicity remains unclear. We use particle image velocimetry to measure a multidimensional migration phenotype for genetically defined human breast epithelial cell lines that range in their in vivo behavior from non-tumorigenic to aggressively metastatic. By using cells with controlled mutations, we show that PTEN deletion enhances collective migration, while Ras activation suppresses it, even when combined with PTEN deletion. These opposing effects on collective migration of two mutations that are frequently found in patient tumors could be exploited in the development of novel treatments for metastatic disease. Our methods are based on label-free phase contrast imaging, and thus could easily be applied to patient tumor cells. The short time scales of our approach do not require potentially selective growth, and thus in combination with label-free imaging would allow multidimensional collective migration phenotypes to be utilized in clinical assessments of metastatic potential.

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Polymeric/Inorganic Multifunctional Nanoparticles for Simultaneous Drug Delivery and Visualization

MRS Proceedings ◽

10.1557/proc-1257-o04-03 ◽

2010 ◽

Vol 1257 ◽

Cited By ~ 2

Author(s):

Andrea Fornara ◽

Alberto Recalenda ◽

Jian Qin ◽

Abhilash Sugunan ◽

Fei Ye ◽

...

Keyword(s):

Drug Delivery ◽

Fluorescence Microscopy ◽

Contrast Agents ◽

Gold Nanorods ◽

In Vitro Cytotoxicity ◽

In Vivo Studies ◽

Multifunctional Nanoparticles ◽

Cytotoxicity Studies

AbstractNanoparticles consisting of different biocompatible materials are attracting a lot of interest in the biomedical area as useful tools for drug delivery, photo-therapy and contrast enhancement agents in MRI, fluorescence and confocal microscopy. This work mainly focuses on the synthesis of polymeric/inorganic multifunctional nanoparticles (PIMN) based on biocompatible di-block copolymer poly(L,L-lactide-co-ethylene glycol) (PLLA-PEG) via an emulsion-evaporation method. Besides containing a hydrophobic drug (Indomethacin), these polymeric nanoparticles incorporate different visualization agents such as superparamagnetic iron oxide nanoparticles (SPION) and fluorescent Quantum Dots (QDs) that are used as contrast agents for Magnetic Resonance Imaging (MRI) and fluorescence microscopy together. Gold Nanorods are also incorporated in such nanostructures to allow simultaneous visualization and photodynamic therapy. MRI studies are performed with different loading of SPION into PIMN, showing an enhancement in T2 contrast superior to commercial contrast agents. Core-shell QDs absorption and emission spectra are recorded before and after their loading into PIMN. With these polymeric/inorganic multifunctional nanoparticles, both MRI visualization and confocal fluorescence microscopy studies can be performed. Gold nanorods are also synthesized and incorporated into PIMN without changing their longitudinal absorption peak usable for lased excitation and phototherapy. In-vitro cytotoxicity studies have also been performed to confirm the low cytotoxicity of PIMN for further in-vivo studies.

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A Pilot Study on Efficacy of Lipid Bubbles for Theranostics in Dogs with Tumors

Cancers ◽

10.3390/cancers12092423 ◽

2020 ◽

Vol 12 (9) ◽

pp. 2423

Author(s):

Inoru Yokoe ◽

Yusuke Murahata ◽

Kazuki Harada ◽

Yuji Sunden ◽

Daiki Omata ◽

...

Keyword(s):

Cervical Region ◽

Focal Liver Lesions ◽

Contrast Imaging ◽

Contrast Enhanced Ultrasonography ◽

Series Of Experiments ◽

Diagnostic Applications ◽

Hepatic Portal ◽

Large Animals

The combined administration of microbubbles and ultrasound (US) is a promising strategy for theranostics, i.e., a combination of therapeutics and diagnostics. Lipid bubbles (LBs), which are experimental theranostic microbubbles, have demonstrated efficacy in vitro and in vivo for both contrast imaging and drug delivery in combination with US irradiation. To evaluate the clinical efficacy of LBs in combination with US in large animals, we performed a series of experiments, including clinical studies in dogs. First, contrast-enhanced ultrasonography using LBs (LB-CEUS) was performed on the livers of six healthy Beagles. The hepatic portal vein and liver tissue were enhanced; no adverse reactions were observed. Second, LB-CEUS was applied clinically to 21 dogs with focal liver lesions. The sensitivity and specificity were 100.0% and 83.3%, respectively. These results suggested that LB-CEUS could be used safely for diagnosis, with high accuracy. Finally, LBs were administered in combination with therapeutic US to three dogs with an anatomically unresectable solid tumor in the perianal and cervical region to determine the enhancement of the chemotherapeutic effect of liposomal doxorubicin; a notable reduction in tumor volume was observed. These findings indicate that LBs have potential for both therapeutic and diagnostic applications in dogs in combination with US irradiation.

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Imaging Subthreshold Voltage Oscillation With Cellular Resolution in the Inferior Olive in vitro

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2020.607843 ◽

2020 ◽

Vol 14 ◽

Author(s):

Kevin Dorgans ◽

Bernd Kuhn ◽

Marylka Yoe Uusisaari

Keyword(s):

Inferior Olive ◽

Brain Slices ◽

Brain Regions ◽

Mammalian Brain ◽

Wide Field ◽

Voltage Imaging ◽

Subthreshold Oscillations ◽

Cellular Resolution

Voltage imaging with cellular resolution in mammalian brain slices is still a challenging task. Here, we describe and validate a method for delivery of the voltage-sensitive dye ANNINE-6plus (A6+) into tissue for voltage imaging that results in higher signal-to-noise ratio (SNR) than conventional bath application methods. The not fully dissolved dye was injected into the inferior olive (IO) 0, 1, or 7 days prior to acute slice preparation using stereotactic surgery. We find that the voltage imaging improves after an extended incubation period in vivo in terms of labeled volume, homogeneous neuropil labeling with saliently labeled somata, and SNR. Preparing acute slices 7 days after the dye injection, the SNR is high enough to allow single-trial recording of IO subthreshold oscillations using wide-field (network-level) as well as high-magnification (single-cell level) voltage imaging with a CMOS camera. This method is easily adaptable to other brain regions where genetically-encoded voltage sensors are prohibitively difficult to use and where an ultrafast, pure electrochromic sensor, like A6+, is required. Due to the long-lasting staining demonstrated here, the method can be combined, for example, with deep-brain imaging using implantable GRIN lenses.

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