Eun-Yeong Park

The glymphatic system in the brain controls the cerebrospinal fluid (CSF) circulation and metabolic waste clearance, which is crucial for understanding the mechanisms and therapeutic opportunities of various brain pathologies. With the rapidly growing interest in its relationship with neurodegenerative conditions, including Alzheimer’s disease, its underlying processes are still not fully understood and remain under active investigation. A representative finding is that the glymphatic flow is passively driven by factors such as vascular pulsation, and studies have been conducted to modulate the glymphatic system using external stimuli to enhance waste clearance or to leverage CSF pathways for delivering chemotherapeutic agents. Particularly, glymphatic flow modulation holds great potential for improving drug delivery to the brain via intrathecal administration as an alternative to conventional systemic delivery, which is restricted by the blood-brain barrier (BBB). This review focuses on ultrasound (US) techniques for glymphatic system modulation, with the aim of augmenting glymphatic flow and ultimately improving drug delivery for brain cancer therapy. Given the limited number of cancer-related studies in the field, we comprehensively review US-based glymphatic modulation research to date and identify their implications and future opportunities for brain cancer applications.

Photoacoustic microscopy enables multi-scale, label-free biomedical imaging; however, limitations associated with system complexity, opto-acoustic alignment, and fragmented operational workflows hinder its widespread adoption. To address these challenges, we present a photoacoustic microscopy platform with fully integrated optical excitation, acoustic detection, scanning, and system control. It combines a ring-shaped ultrasound transducer with an integrated optical and mechanical scanning architecture, incorporating an angled galvanometer scanner and a motorized stage. This platform provides a balanced configuration that optimizes imaging speed, resolution, and coverage, achieving a lateral resolution of 3.00 µm and a versatile field of view extendable up to 28 × 28 mm ² , while maintaining a B-scan acquisition rate of up to 50 Hz. Enabled by a unified hardware-software environment and a streamlined pipeline from data acquisition to quantitative analysis, we demonstrate the system’s translational utility through diverse in vivo applications in mice, including macro-scale anatomical imaging, micro-scale hemodynamic monitoring, contrast-enhanced functional imaging, pharmacodynamic assessment of epinephrine, and longitudinal monitoring of tumor progression. Collectively, these results establish the robustness and versatility of the proposed system, maintaining balanced performance in resolution, speed, and field of view, and positioning it as a practical platform for advanced structural, functional, and pathological imaging in translational biomedical research.

Breast cancer screening with mammography is less effective in women with dense breast tissue, prompting the use of ultrasound (US) imaging. While two- (2D) and three-dimensional (3D) US improve cancer detection, their low specificity leads to frequent unnecessary biopsies. Operator dependence on 2D US has led to the development of 3D automated breast volume scanners (ABVS), but challenges remain in distinguishing benign from malignant lesions. We developed a 3D photoacoustic and ultrasound (PAUS)–ABVS system that integrates a large field-of-view, 768-element transducer to improve diagnostic accuracy. In a clinical study of 61 patients with 36 benign and 30 malignant lesions, multispectral photoacoustic imaging was used to measure blood volume and oxygen saturation within lesions. When combined with standard US BI-RADS (breast imaging reporting and data system) scores, the system achieved a sensitivity of 96.7% and specificity of 66.7%. This performance matched the best outcomes of 2D PAUS and outperformed conventional US. Our results suggest that the PAUS-ABVS can support more accurate breast cancer diagnosis while reducing unnecessary biopsies.

Ultrasound imaging is one of the most widespread biomedical imaging techniques thanks to its advantages such as being non-invasive, portable, non-ionizing, and cost-effective. Ultrasound imaging generally provides two-dimensional cross-sectional images, but the quality and interpretative ability vary based on the experience of the examiner, leading to a lack of objectivity and accuracy. To address these issues, there is a growing demand for three-dimensional ultrasound imaging. Among the various types of transducers used to obtain three-dimensional ultrasound images, this paper focuses on the most standardized probe, the linear array transducer, and provides an overview of the system implementations, imaging results, and applications of volumetric ultrasound imaging from the perspective of scanning methods. Through this comprehensive review, future researchers will gain insights into the advantages and disadvantages of various approaches to three-dimensional imaging systems using linear arrays, providing direction and applicability for system configuration and application.

Volumetric ultrasound imaging has the potential for operator-independent acquisition and enhanced field of view. Panoramic acquisition has many applications across ultrasound; spanning musculoskeletal, liver, breast, and pediatric imaging; and image-guided therapy. Challenges in high-resolution human imaging, such as subtle motion and the presence of bone or gas, have limited such acquisition. These issues can be addressed with a large transducer aperture and fast acquisition and processing. Programmable, ultrafast ultrasound scanners with a high channel count provide an unprecedented opportunity to optimize volumetric acquisition. In this work, we implement nonlinear processing and develop distributed beamformation to achieve fast acquisition over a 47-centimeter aperture. As a result, we achieve a 50-micrometer −6-decibel point spread function at 5 megahertz and resolve in-plane targets. A large volume scan of a human limb is completed in a few seconds, and in a 2-millimeter dorsal vein, the image intensity difference between the vessel center and surrounding tissue was ~50 decibels, facilitating three-dimensional reconstruction of the vasculature.

Three-dimensional bimodal photoacoustic/US imaging provided volumetric and multiparametric information about morphologic and physiologic features of the human foot, potentially useful in diagnosing... Background Monitoring the microcirculation in human feet is crucial in assessing peripheral vascular diseases, such as diabetic foot. However, conventional imaging modalities are more focused on di...

The following conflict of interest disclosure statement was omitted from the published paper:1 “C. Kim has financial interest in Opticho, Inc., which, however,

The phthalocyanine (Pc) and naphthalocyanine (Nc) nanoagents have drawn much attention as contrast agents for photoacoustic (PA) imaging due to their large extinction coefficients and long absorption wavelengths in the near-infrared region. Many investigations have been conducted to enhance Pc/Ncs' photophysical properties and address their poor solubility in an aqueous solution. Many diverse strategies have been adopted, including centric metal chelation, structure modification, and peripheral substitution. This review highlights recent advances on Pc/Nc-based PA agents and their extended use for multiplexed biomedical imaging, multimodal diagnostic imaging, and image-guided phototherapy.

X-ray based radiography, the main modality for diagnostic imaging of bone structures and fractures, provides sensitive images, but it inherently involves potentially harmful X-ray exposure. As non-ionizing alternatives, various optical imaging methods have been explored. Here, we demonstrate non-ionizing, label-free, multispectral photoacoustic (PA) imaging of bones in small animals in vivo, in situ, and ex vivo. Using near-infrared light excitation and acoustic detection, the spine and ribs were successfully visualized in high-resolution PA images. PA 3D volume images of the spine and ribs were clearly visualized together with blood vessels and several organs including the spleen, liver, and cecum, without using any exogenous contrast agent nor ionizing radiation. Quantification results of multispectral PA signals from blood vessels and bones were in good agreement with their absorption coefficients. Further, a rib fracture was photoacoustically imaged. Our results demonstrate PA imaging’s potential as a non-ionizing and label-free technique for imaging bone tissues.