ENHANCING TRANSCRANIAL FOCUSED ULTRASOUND TREATMENT PLANNING WITH SYNTHETIC CT FROM ULTRA-SHORT ECHO TIME (UTE) MRI: A MULTI-TASK DEEP LEARNING APPROACH.

Utilizing a multi-task deep learning framework, this study generated synthetic CT (sCT) images from a limited dataset of Ultrashort echo time (UTE) MRI for transcranial focused ultrasound (tFUS) planning. A 3D Transformer U-Net was employed to produce sCT images that closely replicated actual CT scans, demonstrated by an average Dice coefficient of 0.868 for morphological accuracy.

Response of Serum-isolated Extracellular Vesicles to Focused Ultrasound Blood-Brain Barrier Opening.

The blood-brain barrier (BBB) limits drug delivery to the brain and the movement of neurological biomarkers between the brain and blood. Focused ultrasound-mediated blood-brain barrier opening (FUS-BBBO) noninvasively opens the BBB, allowing increased molecular transport to and from the brain parenchyma. Despite being initially developed as a drug delivery method, FUS-BBBO has shown promise both as a neuroimmunotherapeutic modality, and as a way of improving neurological disease diagnosis via amplification of disease biomarker circulation.

High volume-rate echocardiography for simultaneous imaging of electromechanical activation and cardiac strain of the whole heart in a single heartbeat in humans.

Background: Imaging both electrical and mechanical cardiac function can better characterize cardiac disease and improve patient care. Currently, there is no noninvasive technique that can simultaneously image both electrical and mechanical function of the whole heart at the point of care. Here, our aim is to demonstrate that high volume-rate echocardiography can simultaneously map cardiac electromechanical activation and end-systolic cardiac strain of the whole heart in a single heartbeat.

Amplitude-Modulation Frequency Optimization for Enhancing Harmonic Motion Imaging Performance of Breast Tumors in the Clinic.

Objective: Elastography images tissue mechanical responses and infers the underlying properties to aid diagnosis and treatment response monitoring. The estimation of absolute or relative tumor properties may vary with dimensions even when the mechanical properties remain constant. Harmonic motion imaging (HMI) uses amplitude-modulated (AM) focused ultrasound to interrogate the targeted tissue's viscoelastic properties.

Low hemoglobin causes hematoma expansion and poor intracerebral hemorrhage outcomes.

Objectives: Although lower hemoglobin levels associate with worse intracerebral hemorrhage (ICH) outcomes, causal drivers for this relationship remain unclear. We investigated the hypothesis that lower hemoglobin relates to increased hematoma expansion (HE) risk and poor outcomes using human observational data and assessed causal relationships using a translational murine model of anemia and ICH.

Methods: ICH patients with baseline hemoglobin measurements and serial CT neuroimaging enrolled between 2010-2016 to a multicenter, prospective observational cohort study were studied.

Feasibility of Hologram-Assisted Bilateral Blood-Brain Barrier Opening in Non-Human Primates.

Focused ultrasound (FUS) and microbubbles facilitate blood-brain barrier opening (BBBO) noninvasively, transiently, and safely for targeted drug delivery. Unlike state-of-the-art approaches, in this study, we demonstrate for the first time the simultaneous, bilateral BBBO in non-human primates (NHPs) using acoustic holograms at caudate and putamen structures. The simple and low-cost system with a single-element FUS transducer and 3-D printed acoustic hologram was guided by neuronavigation and a robotic arm.

Optimized ultrasound neuromodulation for non-invasive control of behavior and physiology.

Focused ultrasound can non-invasively modulate neural activity, but whether effective stimulation parameters generalize across brain regions and cell types remains unknown. We used focused ultrasound coupled with fiber photometry to identify optimal neuromodulation parameters for four different arousal centers of the brain in an effort to yield overt changes in behavior. Applying coordinate descent, we found that optimal parameters for excitation or inhibition are highly distinct, the effects of which are generally conserved across brain regions and cell types.

Functional ultrasound (fUS) imaging of displacement-guided focused ultrasound (FUS) neuromodulation in mice.

Focused ultrasound (FUS) stimulation is a promising neuromodulation technique with the merits of non-invasiveness, high spatial resolution, and deep penetration depth. However, simultaneous imaging of FUS-induced brain tissue displacement and the subsequent effect of FUS stimulation on brain hemodynamics has proven challenging thus far. In addition, earlier studies lack in situ confirmation of targeting except for the magnetic resonance imaging-guided FUS system-based studies.

Transcranial Functional Ultrasound Imaging Detects Focused Ultrasound Neuromodulation Induced Hemodynamic Changes in Mouse and Nonhuman Primate Brains .

Focused ultrasound (FUS) is an emerging noinvasive technique for neuromodulation in the central nervous system (CNS). To evaluate the effects of FUS-induced neuromodulation, many studies used behavioral changes, functional magnetic resonance imaging (fMRI) or electroencephalography (EEG). However, behavioral readouts are often not easily mapped to specific brain activity, EEG has low spatial resolution limited to the surface of the brain and fMRI requires a large importable scanner that limits additional readouts and manipulations.

Focused ultrasound-mediated blood-brain barrier opening is safe and feasible with moderately hypofractionated radiotherapy for brainstem diffuse midline glioma.

Background: Diffuse midline glioma (DMG) is a pediatric tumor with dismal prognosis. Systemic strategies have been unsuccessful and radiotherapy (RT) remains the standard-of-care. A central impediment to treatment is the blood-brain barrier (BBB), which precludes drug delivery to the central nervous system (CNS).

An all-ultrasound cranial imaging method to establish the relationship between cranial FUS incidence angle and transcranial attenuation in non-human primates in 3D.

Focused ultrasound (FUS) is a non-invasive and non-ionizing technique which deploys ultrasound waves to induce bio-effects. When paired with acoustically active particles such as microbubbles (MBs), it can open the blood brain barrier (BBB) to facilitate drug delivery otherwise inhibited due to the presence of BBB. One of the parameters that affects the FUS beam propagation is the beam incidence angle on the skull.

Functional Cerebral Neurovascular Mapping During Focused Ultrasound Peripheral Neuromodulation of Neuropathic Pain.

Background: Nociceptive pain is required for healthy function, yet, neuropathic pain (disease or injury) can be severely debilitating. Though a wide-array of treatment options are available, they are often systemic and/or invasive. As a promising neuromodulation treatment, Focused ultrasound (FUS) is a noninvasive and highly spatially-targeted technique shown to stimulate neural activity, yet, effects on pain signaling are currently unknown.

Modulation of cardio-respiratory activity in mice via transcranial focused ultrasound.

Objective: The objective of this study was to investigate the effect of FUS on autonomic nervous system activity, including heart and respiratory rates, and to separate the thermal modulation from combined thermal and mechanical FUS effects.

Methods: The thalamus and hypothalamus of wild-type mice were sonicated with a continuous-wave, 2 MHz FUS transducer at pressures of 425 and 850 kPa for 60 seconds. Cardiac and respiratory rates were monitored as signs of autonomic nervous activity.

Optimization of the Tracking Beam Sequence in Harmonic Motion Imaging.

Harmonic motion imaging (HMI) is an ultrasound elastography technique that estimates the viscoelastic properties of tissues by inducing localized oscillatory motion using focused ultrasound (FUS). The resulting displacement, assumed to be inversely proportional to the tissue local stiffness, is estimated using an imaging array based on RF speckle tracking. In conventional HMI, this is accomplished with plane-wave (PW) imaging, which inherently suffers from low lateral resolution.

Harmonic Motion Imaging-Guided Focused Ultrasound Ablation: Comparison of Three Focused Ultrasound Interference Filtering Methods.

Objective: Harmonic motion imaging (HMI) is an acoustic radiation force-based elasticity imaging technique, which can be used to monitor changes in tissue mechanical properties caused by focused ultrasound (FUS)-induced thermal ablation. In conventional HMI, the amplitude-modulated FUS sequence and imaging pulse are transmitted simultaneously. With this method, the high-amplitude FUS signal must be separated from the imaging data for tissue displacement estimation.

Characterization of the responses of brain macrophages to focused ultrasound-mediated blood-brain barrier opening.

The opening of the blood-brain barrier (BBB) by focused ultrasound (FUS) coupled with intravenously injected microbubbles can be leveraged as a form of immunotherapy for the treatment of neurodegenerative disorders. However, how FUS BBB opening affects brain macrophages is not well understood. Here by using single-cell sequencing to characterize the distinct responses of microglia and central nervous system-associated macrophages (CAMs) to FUS-mediated BBB opening in mice, we show that the treatment remodels the immune landscape via the recruitment of CAMs and the proliferation of microglia and via population size increases in disease-associated microglia.

Polyvinyl Alcohol Phantoms With Heterogeneous Plaques: Estimation of Pulse Wave Velocity at the Stenotic Region Using Pulse Wave Imaging.

Objective: Plaque characterization is essential for stroke prevention. In the study reported herein, we describe a heterogeneous phantom manufacturing technique with varying plaque compositions of different stiffness using polyvinyl alcohol (PVA) to emulate stenotic arteries and evaluated the use of pulse wave imaging (PWI) to assess plaque stiffness by comparing derived pulse wave velocities, with the goal of assessing plaque vulnerability and identifying high-risk patients for stroke.

Methods: Five stenotic phantoms (50% stenosis) were fabricated by pouring PVA solutions into 3-D-printed molds.

Feasibility of Phase Velocity Imaging Using Multi Frequency Oscillation-Shear Wave Elastography.

Objective: To assess viscoelasticity, a pathologically relevant biomarker, shear wave elastography (SWE) generally uses phase velocity (PV) dispersion relationship generated via pulsed acoustic radiation force (ARF) excitation pulse. In this study, a multi-frequency oscillation (MFO)- excitation pulse with higher weight to higher frequencies is proposed to generate PV images via the generation of motion with energy concentrated at the target frequencies in contrast to the broadband frequency motion generated in pulsed SWE (PSWE).

Methods: The feasibility of MFO-SWE to generate PV images at 100 to 1000 Hz in steps of 100 Hz was investigated by imaging 6 and 70 kPa inclusions with 6.