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 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.

Photoacoustic imaging is a promising modality with potentially broad applications. To achieve high-quality images, an appropriate detection technique suitable for the specific application is crucial. This review categorizes detection technologies into two primary methods: ultrasonic transducers and optical sensing. We present their detection principles and recent progress, from conventional to advanced technologies. We finally conclude by providing a detailed classification, outlining the main characteristics of each technique.

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.

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.

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.