Focused Ultrasound Research Articles

Delivering Gd-Labeled IgG Antibodies Into the Mouse Brain Following Focused Ultrasound Treatment.

Antibody-based therapy has emerged as a powerful tool for targeted treatment of neurological diseases, such as brain cancer and neurodegenerative disorders. However, direct, scalable, and safe confirmation of antibody delivery into the brain remains challenging. Antibodies can be effectively tracked when tagged with molecules that are detectable by medical imaging modalities, such as MRI, PET, or SPECT. In this study, we aimed to confirm gadolinium (Gd)-labeled IgG antibody delivery into the mouse brain using MRI, following exposure to focused ultrasound (FUS) and circulating microbubbles. We acquired MR images of the mouse brain to evaluate antibody delivery into the targeted brain region. First, we quantified the MR signal of Gd-labeled IgG antibodies in phantoms using preclinical 9.4 T and clinical 3 T MRI scanners. Then, we determined optimal ultrasound and MR imaging parameters to non-invasively and safely disrupt the blood-brain barrier in a localized and reversible manner and effectively monitor antibody delivery into the murine brain, respectively. We confirmed that IgG antibodies can be reliably delivered into the murine brain using FUS and microbubble treatment and that we can track their biodistribution within the brain parenchyma using clinically relevant MR image sequences. The maximum detected volume of Gd-IgG antibody delivery (n = 4) was determined to be 0.12 ± 0.02 mm3 at t = 75.3 ± 17.3 minutes following treatment. This work paves the way for a scalable and non-ionizing method for performing and evaluating antibody delivery into the brain.

Updates in Diagnostic Techniques and Experimental Therapies for Diffuse Intrinsic Pontine Glioma

Diffuse intrinsic pontine glioma (DIPG) is a rare but extremely malignant central nervous system tumor primarily affecting children that is almost universally fatal with a devastating prognosis of 8-to-12-month median survival time following diagnosis. Traditionally, DIPG has been diagnosed via MR imaging alone and treated with palliative radiation therapy. While performing surgical biopsies for these patients has been controversial, in recent years, advancements have been made in the safety and efficacy of surgical biopsy techniques, utilizing stereotactic, robotics, and intraoperative cranial nerve monitoring as well as the development of liquid biopsies that identify tumor markers in either cerebrospinal fluid or serum. With more molecular data being collected from these tumors due to more frequent biopsies being performed, multiple treatment modalities including chemotherapy, radiation therapy, immunotherapy, and epigenetic modifying agents continue to be developed. Numerous recent clinical trials have been completed or are currently ongoing that have shown promise in extending survival for patients with DIPG. Focused ultrasound (FUS) has also emerged as an additional promising adjunct invention used to increase the effectiveness of therapeutic agents. In this review, we discuss the current evidence to date for these advancements in the diagnosis and treatment of DIPG.

Focused ultrasound and microbubble-mediated delivery of CRISPR-Cas9 ribonucleoprotein to human induced pluripotent stem cells.

Focused ultrasound and microbubble-mediated delivery of CRISPR-Cas9 ribonucleoprotein to human induced pluripotent stem cells.

Evaluation of focused ultrasound modulation of the blood-brain barrier in gray and white matter.

Evaluation of focused ultrasound modulation of the blood-brain barrier in gray and white matter.

Empirical Model of Focused Ultrasound-Mediated Treatment for Chemotherapy Delivery to Brain Tumors.

Empirical Model of Focused Ultrasound-Mediated Treatment for Chemotherapy Delivery to Brain Tumors.

Evaluation of blood-tumor barrier permeability and doxorubicin delivery in rat brain tumor models using additional focused ultrasound stimulation

Focused ultrasound (FUS) has emerged as a promising technique for temporarily disrupting the blood-brain barrier (BBB) and blood-tumor barrier (BTB) to enhance the delivery of therapeutic agents. Despite its potential, optimizing FUS to maximize drug delivery while minimizing adverse effects remains a significant challenge. In this study, we evaluated a novel FUS protocol that incorporates additional FUS stimulation without microbubbles (MBs) (“FUS protocol”) prior to conventional BBB disruption with MBs (“BBBD protocol”) in a rat brain tumor model (n = 35). This approach aimed to validate its effectiveness in enhancing BBB/BTB disruption and facilitating doxorubicin delivery. T1-weighted contrast-enhanced and dynamic contrast-enhanced (DCE) MRI demonstrated significant increases in signal intensity and permeability (Ktrans) in the tumor region under the “FUS + BBBD protocol”, with 2.65-fold and 2.08-fold increases, respectively, compared to the non-sonicated contralateral region. These values were also elevated compared to the conventional “BBBD protocol” by 1.45-fold and 1.25-fold, respectively. Furthermore, doxorubicin delivery in the targeted region increased by 1.91-fold under the “FUS + BBBD protocol”, compared to a 1.44-fold increase using the conventional “BBBD protocol”. This novel FUS approach offers a promising, cost-effective strategy for enhancing drug delivery to brain tumors. While further studies are required to assess its applicability with different chemotherapeutics and tumor types, it holds significant potential for improving brain tumor treatment in both preclinical and clinical settings.

Abstract A021: Spatiotemporal Regulation of Chimeric Antigen Receptor T-cells Using Focused Ultrasound Therapy to Enable Use of High-Affinity Binders

Abstract Pediatric High Grade Glioma (HGG) is an aggressive cancer with a 5-year survival rate of just 10-20% (Fangusaro, 2012). While previous studies using chimeric antigen receptor (CAR) T-cells for brain malignancies demonstrated tolerability (Majzner et al., 2022; Vitanza et al., 2021; Vitanza et al., 2023), the low survival rates demand more efficacious therapies (Majzner et al., 2022). In this study, we perform in vitro modeling of spatiotemporally regulated high-affinity CARs targeting the GD2 antigen to enable use of highly potent CAR variants while mitigating on-target, off-tumor toxicity. By placing CAR affinity variants under control of a heat shock promoter, thermal energy delivered to the tumor tissue by focused ultrasound (FUS) induces CAR expression (Wu et al., 2021) at an optimal temperature of 43oC. We first determine FUS-controlled CAR induction and decay kinetics in vitro for selected signaling domain architectures as well as affinity variants. Following codon optimization, differences in basal expression at 37oC from the heat shock promoter were noted for the three signaling domain architectures, with 28z and BBz displaying the highest and lowest levels of aberrant expression, respectively. Next, we compare expression of CAR constructs with and without 3 cycles of heat shock at 43oC in CAR-T cells. Then, using live cell imaging, we analyze the kinetics of expression and decay of the CAR following heat shock. Finally, we perform effector function assays of the CAR-T cells to compare the cytotoxicity and persistence for each construct. We identify the CAR architecture harboring the CD28 transmembrane domain and the 4-1BB cytoplasmic domain as the optimal balance between basal and induced expression. We plan to move this architecture forward to in vivo studies to assess the ability to maintain robust tumor lysis and minimal on-target, off-tumor toxicity. Citation Format: Edward Trope, Yun-Yun Su, Rie Nakata, Magda Golyska, Sarah Richman. Spatiotemporal Regulation of Chimeric Antigen Receptor T-cells Using Focused Ultrasound Therapy to Enable Use of High-Affinity Binders [abstract]. In: Proceedings of the AACR IO Conference: Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2025 Feb 23-26; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2025;13(2 Suppl):Abstract nr A021.

Therapeutic Ultrasound for Multimodal Cancer Treatment: A Spotlight on Breast Cancer.

Cancer remains a leading cause of mortality worldwide, and the demand for improved efficacy, precision, and safety of management options has never been greater. Focused ultrasound (FUS) is a rapidly emerging strategy for nonionizing, noninvasive intervention that holds promise for the multimodal treatment of solid cancers. Owing to its versatile array of bioeffects, this technology is now being evaluated across preclinical and clinical oncology trials for tumor ablation, therapeutic delivery, radiosensitization, sonodynamic therapy, and enhancement of tumor-specific immune responses. Given the breadth of this burgeoning domain, this review places a spotlight on recent advancements in breast cancer care to exemplify the multifaceted role of FUS technology for oncology indications-outlining physical principles of FUS-mediated thermal and mechanical bioeffects, giving an overview of results from recent preclinical and clinical studies investigating FUS with and without adjunct therapeutics in primary or disseminated breast cancer settings, and offering perspectives on the future of the field.

Focused ultrasound as an emerging therapy for neuropsychiatric disease: Historical perspectives and a review of current clinical data.

Psychiatric disorders are a common source of disease morbidity with high rates of refractoriness to first-line treatments. As such, many have investigated the utility of neurosurgical interventions for treatment-resistant forms of these conditions. More recently among these, functional neurosurgical techniques using high- and low-intensity focused ultrasound (FUS) have emerged as promising options in this arena, largely due to their minimally-invasive nature and encouraging early safety and efficacy data. Existing clinical data have thus far demonstrated FUS to be a potentially useful intervention for treatment-refractory forms of obsessive-compulsive disorder, major depressive disorder, various anxiety disorders, substance-use disorder, and schizophrenia. This report presents a comprehensive review of existing clinical trial data, summarizing key findings, study specifications, and providing critical analysis. In addition to giving the most complete summary of modern clinical research on this topic to date, this report characterizes the current state of this body of literature using bibliometric analysis, succinctly highlighting the most investigated topics and the most promising areas of modern investigation. Based on our review of the literature, current work on this topic is highly heterogeneous with regard to specific treatment protocols and anatomic targets for FUS - targeting multiple nuclei at a wide variety of intensities. We recommend that future studies aim to clarify more precise therapeutic targets and specific treatment protocols which optimize the efficacy of these techniques.

A high magnetic resonance imaging (MRI) contrast agar/silica-based phantom for evaluating focused ultrasound (FUS) protocols.

A high magnetic resonance imaging (MRI) contrast agar/silica-based phantom for evaluating focused ultrasound (FUS) protocols.

Clinical Trials of Focused Ultrasound for Brain Tumors.

It is unclear as to where we stand with respect to utilizing emerging focused ultrasound (FUS) technology in the setting of brain tumor treatment in pediatric patients, such as malignant diffuse intrinsic pontine glioma, and various adult counterparts. Correspondingly, the aim of this study was to present a contemporary summary of all pertinent clinical trials to date. The ClinicalTrials.gov database was reviewed in January 2025 for all possible clinical trials involving FUS in the management of brain tumors. These were then screened against selection criteria to identify pertinent clinical trials. A total of 30 clinical trials were identified. The majority were focused on adult patients (24/30, 80%), with the most common tumor type being glioblastoma (GBM) (14/30, 47%). There were also trials focused on pediatric patients only (5/30, 17%), as well as diffuse intrinsic pontine glioma (DIPG) (5/30, 17%). The most prevalent primary outcome of interest was safety (26/30, 87%). The majority of trials were active, either recruiting currently (12/30, 40%), or active but not recruiting currently (3/30, 10%). North America (22/30, 73%) was the most common location for the primary coordinating institution, and the median number of institutions per trial was one. The median expected start year for all trials was 2021, and the completion year was 2024. To date, there have been no results (interim or final) formally reported, although preliminary reports in the literature indicate this to be a safe procedure. Anecdotal trends suggest later trials target the blood-brain barrier more, involve more pediatric patients, and are more based in the United States. There exists a number of early-stage clinical trials investigating FUS to treat a variety of brain tumors in pediatric patients, as well as adult patients, with a significant clinical potential to improve outcomes. To date, no official results have been published, however anecdotal evidence is promising, and a number of results are expected soon.

An Open Access Resource for Marmoset Neuroscientific Apparatus

Abstract The use of the common marmoset (Callithrix jacchus) for neuroscientific inquiry has grown precipitously over the past two decades. Despite windfalls of grant support from funding initiatives in North America, Europe, and Asia to model human brain diseases in the marmoset, marmoset-specific apparatus are of sparse availability from commercial vendors and thus are often developed and reside within individual laboratories. Through our collective research efforts, we have designed and vetted myriad designs for awake or anesthetized magnetic resonance imaging (MRI), positron emission tomography (PET), computed tomography (CT), as well as focused ultrasound (FUS), electrophysiology, optical imaging, surgery, and behavior in marmosets across the age-span. This resource makes these designs openly available, reducing the burden of de novo development across the marmoset field. The computer-aided-design (CAD) files are publicly available through the Marmoset Brain Connectome (MBC) resource (https://www.marmosetbrainconnectome.org/apparatus/) and include dozens of downloadable CAD assemblies, software and online calculators for marmoset neuroscience. In addition, we make available a variety of vetted touchscreen and task-based fMRI code and stimuli. Here, we highlight the online interface and the development and validation of a few yet unpublished resources: Software to automatically extract the head morphology of a marmoset from a CT and produce a 3D printable helmet for awake neuroimaging, and the design and validation of 8-channel and 14-channel receive arrays for imaging deep structures during anatomical and functional MRI.

Integration of focused ultrasound and dynamic imaging control system for targeted neuro-modulation.

Integration of focused ultrasound and dynamic imaging control system for targeted neuro-modulation.

Focused ultrasound widely broadens AAV-delivered Cas9 distribution and activity.

Because children have little temporal exposure to environment and aging, most pediatric neurological diseases are inherent, i.e. genetic. Since postnatal neurons and astrocytes are mostly non-replicating, gene therapy and genome editing present enormous promise in child neurology. Unlike in other organs, which are highly permissive to adeno-associated viruses (AAV), the mature blood-brain barrier (BBB) greatly limits circulating AAV distribution to the brain. Intrathecal administration improves distribution but to no more than 20% of brain cells. Focused ultrasound (FUS) opens the BBB transiently and safely. In the present work we opened the hippocampal BBB and delivered a Cas9 gene via AAV9 intrathecally. This allowed brain first-pass, and subsequent vascular circulation and re-entry through the opened BBB. The mouse model used was of Lafora disease, a neuroinflammatory disease due to accumulations of misshapen overlong-branched glycogen. Cas9 was targeted to the gene of the glycogen branch-elongating enzyme glycogen synthase. We show that FUS dramatically (2000-fold) improved hippocampal Cas9 distribution and greatly reduced the pathogenic glycogen accumulations and hippocampal inflammation. FUS is in regular clinical use for other indications. Our work shows that it has the potential to vastly broaden gene delivery or editing along with clearance of corresponding pathologic basis of brain disease.

Lipid nanoparticles and transcranial focused ultrasound enhance the delivery of SOD1 antisense oligonucleotides to murine brain

Lipid nanoparticles and transcranial focused ultrasound enhance the delivery of SOD1 antisense oligonucleotides to murine brain

Subcellular Cavitation Bubbles Induce Cellular Mechanolysis and Collective Wound Healing in Ultrasound-Inflicted Cell Ablation.

Focused ultrasound (FUS) has been widely adopted in medical and life science researches. Although various physical and biological effects of FUS have been well-documented, there is still a lack of understanding and direct evidence on the biological mechanism of therapeutic cell ablation caused by high-intensity ultrasound (HIFU) and the subsequent wound healing responses. This study develops an enclosed cell culture device that synergistically combines non-invasive FUS stimulation and real-time, on-the-fly live-cell imaging, providing an in vitro platform to explore short and long-term biological effects of ultrasound. The process, mechanism, and wound healing response of cell ablation induced by HIFU are elucidated, revealing a unique mechanism, termed ultrasound-inflicted cellular mechanolysis, that is mediated by growing subcellular cavitation air bubbles under confined contact with cells. This provides a previously unappreciated mechanism for understanding the biomechanical principles of ultrasound-based ablative therapy. A post-ablation phantom layer is also revealed that serves as a guiding cue for collective cell migration during wound healing, thereby providing a biomimetic model for studying wound healing after HIFU-inflicted damage. Together, this study provides theoretical and technological basis for advancing the understanding of the biological effects of ultrasound-based ablative therapy and inspiring clinically relevant applications in the future.

Fabricating and Labeling Microbubbles with Fluorescent and Radioactive Tracers.

Microbubbles are lipid-shelled, gas-filled particles that have evolved from vascular ultrasound contrast agents into revolutionary cancer therapy platforms. When combined with therapeutic focused ultrasound (FUS), they can safely and locally overcome physiological barriers (e.g., blood-brain barrier), deliver drugs to otherwise inaccessible cancers (e.g., glioblastoma and pancreatic cancer), and treat neurodegenerative diseases. The therapeutic arsenal of microbubble-FUS is advancing in new directions, including synergistic combination radiotherapy, multimodal imaging, and all-in-one drug loading and delivery from microbubble shells. Labeling microbubbles with radiotracers is key to establishing these expanded theranostic capabilities. However, existing microbubble radiolabeling strategies rely on purification methodologies known to perturb microbubble physicochemical properties, use short-lived radioisotopes, and do not always yield stable chelation. Collectively, this creates ambiguity surrounding the accuracy of microbubble radioimaging and the efficiency of tumor radioisotope delivery. This protocol describes a new one-pot, purification-free microbubble labeling methodology that preserves microbubble physicochemical properties while achieving >95% radioisotope chelation efficiency. It is versatile and can be applied successfully across custom and commercial microbubble formulations with differing acyl lipid chain length, charge, and chelator/probe (porphyrin, DTPA, DiI) composition. It can be adaptively applied during ground-up microbubble fabrication and to pre-made microbubble formulations with modular customizability of fluorescence and multimodal fluorescence/radioactive properties. Accordingly, this flexible method enables the production of tailored, traceable (radio, fluorescent, or radio/fluorescent active) multimodal microbubbles that are useful for advancing mechanistic, imaging, and therapeutic microbubble-FUS applications.

Ultrasound Erosion of Rabbit Liver Induced by Locally Injected Phase-Shift Acoustic Droplets and With Lauromacrogol.

Our previous studies have found that low-frequency, low-pressure, weakly focused ultrasound (FUS) can induce acoustic droplet vaporization (ADV) of perfluoropentane (PFP) droplets and result in localized liver and prostate tissue controllable cavitation resonance and mechanical damage. To further investigate the mechanical erosion induced by ultrasound and locally injected phase-shift acoustic droplets in rabbit liver. The liver of each rabbit was treated with perfluoromethylcyclopentane (PFMCP) alone, FUS combined with PFMCP (FUS + PFMCP), and FUS combined with PFP (FUS + PFP). Two-dimensional ultrasound images showed that immediately after the completion of FUS + PFP group treatments, a high echogenicity bubble cloud could be observed, while there were no significant differences in the PFMCP and FUS + PFMCP group before and after treatment. The liver necrotic area in the FUS + PFP group was 6.2 times that of the FUS + PFMCP group (P < .05), whereas no liver necrosis was observed in the PFMCP group. At the same time, the number of vacuoles in the liver in the FUS + PFP group was approximately 70 times that of the FUS + PFMCP group (P < .001), whereas no vacuoles were observed in the PFMCP group (P < .001). Both FUS + PFMCP and PFMCP alone have poor mechanical erosion in liver tissue, and may even cause no damage. Only PFP droplets combined with FUS can cause significant mechanical destruction of liver tissue, leading to tissue necrosis in the droplet injection area.

Erratum in: Focused Ultrasound as a Novel Non-Invasive Method for the Delivery of Gold Nanoparticles to Retinal Ganglion Cells.

Erratum in: Focused Ultrasound as a Novel Non-Invasive Method for the Delivery of Gold Nanoparticles to Retinal Ganglion Cells.

Focused Ultrasound Neuromodulation: Exploring a Novel Treatment for Severe Opioid Use Disorder.

Focused Ultrasound Neuromodulation: Exploring a Novel Treatment for Severe Opioid Use Disorder.