A photoacoustic finder fully integrated with a solid-state dye laser and transparent ultrasound transducer

Abstract

The standard-of-care for evaluating lymph node status in breast cancers and melanoma metastasis is sentinel lymph node (SLN) assessment performed with a handheld gamma probe and radioisotopes. However, this method inevitably exposes patients and physicians to radiation, and the special facilities required limit its accessibility. Here, we demonstrate a non-ionizing, cost-effective, handheld photoacoustic finder (PAF) fully integrated with a solid-state dye laser and transparent ultrasound transducer (TUT). The solid-state dye laser handpiece is coaxially aligned with the spherically focused TUT. The integrated finder readily detected photoacoustic signals from a tube filled with methylene blue (MB) beneath a 22 mm thick layer of chicken tissue. In live animals, we also photoacoustically detected both SLNs injected with MB and subcutaneously injected melanomas. We believe that our radiation-free and inexpensive PAF can play a vital role in SLN assessment.

Whole-Body Photoacoustic Imaging Techniques for Preclinical Small Animal Studies

“…Developing an integrated probe that consists of optical fibers inside of the US transducer can significantly improve the light delivery efficiency. Transparent US transducers, which have recently been introduced, are another option for improving light delivery efficacy [ 85 , 86 ]. In addition, adequate image reconstruction algorithms with volumetric evaluation can improve the visibility of the resulting images [ 87 , 88 , 89 ].…”

Photoacoustic imaging for microcirculation

“…Recently, TUTs based on the piezoelectric active element in particular have gained significant interest from multiple groups in the photoacoustic and ultrasound community due to their versatility and cost effectiveness 170–176 . For example, Chen et al 177 used LiNbO3‐based TUT to image chicken embryo vasculature and for melanoma detection.…”

Fully integrated photoacoustic microscopy and photoplethysmography of human in vivo

“…Thus, the capability of PAI renders it useful for imaging blood vessels and monitoring hemodynamics by highlighting hemoglobin at visible wavelengths [8] . In addition, PAI enables multiscale imaging from microscopy to clinical applications, depending on which optical and ultrasonic subsystems are combined [9] , [10] , [11] , [12] , [13] , [14] , [15] . Most clinical studies have been conducted in the form of photoacoustic tomography with a high intensity pulsed laser and medical ultrasound machines that are widely used in hospitals and clinics [16] , [17] , [18] , [19] .…”