No abstract

For over two decades photoacoustic imaging has been tested clinically, but successful human trials have been limited. To enable quantitative clinical spectroscopy, the fundamental issues of wavelength-dependent fluence variations and inter-wavelength motion must be overcome. Here we propose a real-time, spectroscopic photoacoustic/ultrasound (PAUS) imaging approach using a compact, 1-kHz rate wavelength-tunable laser. Instead of illuminating tissue over a large area, the fiber-optic delivery system surrounding an US array sequentially scans a narrow laser beam, with partial PA image reconstruction for each laser pulse. The final image is then formed by coherently summing partial images. This scheme enables (i) automatic compensation for wavelength-dependent fluence variations in spectroscopic PA imaging and (ii) motion correction of spectroscopic PA frames using US speckle tracking in real-time systems. The 50-Hz video rate PAUS system is demonstrated in vivo using a murine model of labelled drug delivery.

Background We aimed to analyse the trends in ageism among health care providers and medical students in the Republic of Korea. Methods We used the Fraboni Scale of Ageism (FSA), Relating to Older People Evaluation (ROPE) questionnaire, Anxiety about Aging Scale (AAS), and the Facts on Aging Quiz II to assess ageism in medical students (n=90), nurses (n=114), and physicians (n=83). We grouped health care providers based on the percentage of aged patients (over 65 years) that they treated. Results Compared to the other groups, physicians had more knowledge about aging and the highest and lowest total scores in the FSA and ROPE, respectively. The total FSA scores were negatively correlated with the percentage of aged patients treated. Regarding the ROPE score, negative and positive ageist behaviors were positively correlated with the percentage of aged patients. Conclusions: Ageism and ageist behavior among physicians differed from previous reports and those of the other groups mentioned in the present study. Although physicians had more knowledge of aging, they had expressed a high levels of ageism. However, they did not act ageistically. Health care providers who treat a large number of older patients had minimal ageism but more ageist behavior. These findings indicate that continued education of geriatrics and ageism for medical staff and prospective medical personnel could help improve this situation.

Combinations of novel pulse-echo acquisitions and clutter filtering techniques can improve the sensitivity and the specificity of power Doppler (PD) images, thus reducing the need for exogenous contrast enhancement. We acquire echoes following bursts of Doppler pulse transmissions sparsely applied in regular patterns over long durations. The goal is to increase the sensitivity of the acquisition to slow disorganized patterns of motion from the peripheral blood perfusion. To counter a concomitant increase in clutter signal power, we arrange the temporal echo acquisitions into two data-array axes, combine them with a spatial axis for the tissue region of interest, and apply 3-D singular-value decomposition (SVD) clutter filtering. Successful separation of blood echoes from other echo signal sources requires that we partition the 3-D SVD core tensor. Unfortunately, the clutter and blood subspaces do not completely uncouple in all situations, so we developed a statistical classifier that identifies the core tensor subspace dominated by tissue clutter power. This paper describes an approach to subspace partitioning as required for optimizing PD imaging of peripheral perfusion. The technique is validated using echo simulation, flow-phantom data, and in vivo data from a murine melanoma model. We find that for narrow eigen-bandwidth clutter signals, we can routinely map phantom flows and tumor perfusion signals at speeds less than 3 mL/min. The proposed method is well suited to peripheral perfusion imaging applications.