High-speed label-free ultraviolet photoacoustic microscopy for histology-like imaging of unprocessed biological tissues

Abstract

Ultraviolet photoacoustic microscopy (UV-PAM) has recently been demonstrated as a potential imaging tool for surgical margin analysis (SMA). UV-PAM does not require staining or micrometer-thick slicing, which is inevitable in conventional histological imaging. To promote UV-PAM as a practical intraoperative diagnostic tool, the imaging speed should be improved while preserving the high-resolution imaging capability and simplistic system design. In this Letter, we developed a galvanometer mirror-based UV-PAM (GM-UV-PAM) system for high-speed histology-like imaging. By using a UV laser with a high repetition rate (55 kHz) and a one-dimensional galvanometer mirror, our GM-UV-PAM system can generate subcellular images in less than 15 min for a typical brain biopsy ( 5 m m × 5 m m ), with a lateral resolution of ∼ 1.0 µ m . The images of mouse brain slices obtained by our GM-UV-PAM system show that it can provide histological information for SMA.

High-speed high-resolution laser diode-based photoacoustic microscopy for in vivo microvasculature imaging

“…The laser beam is then reflected by a 1D GM before it is focused by an objective lens (LMU-20X-UVB, f 4 = 9.9 mm, Thorlabs, Inc.) onto the sample for PA signals excitation, achieving rapid scanning with a line-scanning interval of 50 μm on the sample. A hybrid scanning that synchronizes 1D optical and two-dimensional mechanical scanning is applied to achieve fast imaging for the whole sample [7,15]. The laser-induced PA signals will be detected by a focused ultrasonic transducer (V324-SU, 25 MHz central frequency, Olympus NDT, Inc.), and amplified by two amplifiers (56 dB, two ZFL-500LN-BNC+, Minicircuit, Inc.).…”

“…The details about achieving high imaging speed using 1D GM can be found in our previous work [7]. In brief, as shown in the scanning trajectory (Fig.…”

“…Photoacoustic tomography is a hybrid imaging modality in which the detected ultrasonic signals are induced by the absorption of pulsed light [1]. Taking the advantage of intrinsic optical absorption contrast, photoacoustic microscopy (PAM) has been widely used to provide high-resolution and label-free images for functional, metabolic, and histological imaging [2][3][4][5][6][7][8]. However, the costly and bulky lasers, such as Q-switched diodepumped solid-state laser, Ti:sapphire laser, or optical parametric oscillator laser, are usually required to generate high-energy light pulses with a short pulse width for PA signal generation, preventing the wide usage of PAM system for clinical applications.…”

Dual-foci fast-scanning photoacoustic microscopy with 3.2-MHz A-line rate

“…As an emerging biomedical imaging technique, optical-resolution photoacoustic microscopy (OR-PAM) has a sub-cellular resolution, rich optical absorption contrasts, and label-free imaging ability [ [1] , [2] , [3] , [4] , [5] , [6] , [7] , [8] , [9] , [10] , [11] , [12] ]. Fast speed is of great importance for improving throughput and the study of physiological or pathological changes in vivo, such as brain activities, drug responses, and tumor metastasis processes, et al [ [13] , [14] , [15] , [16] , [17] ].…”

High-throughput, label-free and slide-free histological imaging by computational microscopy and unsupervised learning

“…2) with optical sectioning capability enable slide-free imaging of thick resection specimens, greatly simplifying the procedures associated with tissue sectioning in conventional FFPE. The scanning-based depth-resolved approaches, including confocal microscopy 3,4 , photoacoustic microscopy (PAM) 5,6 , multiphoton microscopy (MPM) 7 , stimulated Raman scattering (SRS) 8,9 , second harmonic generation (SHG) 10 , and their spectral multiplexing 11,12 , enables surface profiling of bulk tissues via two-dimensional/three-dimensional (2D)/(3D) scanning of a tightly focused laser beam. However, the imaging throughput is therefore restricted to tens of megapixels (Supplementary Fig.…”