High-speed simultaneous multiscale photoacoustic microscopy

Mohesh Moothanchery,Renzhe Bi,Malini Olivo,Chulhong Kim,Jin Young Kim,Ghayathri Balasundaram

doi:10.1117/1.jbo.24.8.086001

Abstract

.Photoacoustic microscopy (PAM) is a fast-growing biomedical imaging technique that provides high-resolution in vivo imaging beyond the optical diffusion limit. Depending on the scalable lateral resolution and achievable penetration depth, PAM can be classified into optical resolution PAM (OR-PAM) and acoustic resolution PAM (AR-PAM). The use of a microelectromechanical systems (MEMS) scanner has improved OR-PAM imaging speed significantly and is highly beneficial in the development of miniaturized handheld devices. The shallow penetration depth of OR-PAM limits the use of such devices for a wide range of clinical applications. We report the use of a high-speed MEMS scanner for both OR-PAM and AR-PAM. A high-speed, wide-area scanning integrated OR-AR-PAM system combining MEMS scanner and raster mechanical movement was developed. A lateral resolution of and penetration depth in vivo was achieved using OR-PAM at 586 nm, whereas a lateral resolution of and penetration depth of in vivo was achieved using AR-PAM at 532 nm.

Highlights

Photoacoustic microscopy (PAM) is a promising, high-resolution biomedical imaging technique based on the photoacoustic effect, which provides high sensitivity toward optical absorption at greater depths.[1,2,3,4]
Compared to other optical imaging techniques, such as confocal microscopy, optical coherence tomography, and two-photon microscopy,[5,6,7] PAM does not rely on backscattered photons, but the detection of low scattered acoustic waves makes the technique suitable for microscopic imaging at greater depth
To characterize the optical resolution PAM (OR-PAM) lateral resolution, a test target having micrometer lines was scanned along the same edge with 0.5-μm step size

Summary

Introduction

Photoacoustic microscopy (PAM) is a promising, high-resolution biomedical imaging technique based on the photoacoustic effect, which provides high sensitivity toward optical absorption at greater depths.[1,2,3,4] In PAM, the absorption of light by endogenous contrast agents (hemoglobin, melanin, water, etc.) will induce temperature rise and in turn produce acoustic waves. Imaging speed limitation in OR-PAM has improved significantly with the MEMS scanner.[21,22] Using a MEMS scanner in the optical resolution mode (MEMS scanner-based OR-PAM), miniaturized handheld PAI devices have been developed.[23,24]. The combined OR-AR-PAM imaging using the MEMS scanner will be beneficial for the development of miniaturized handheld scanning devices for the detection of microvascular changes which occur as part of inflammatory skin disorders such as eczema and psoriasis. The proposed OR-AR-PAM system will potentially fulfill the ultimate goal of high-resolution deep tissue imaging for various biomedical imaging applications. The ability to acquire both OR- and AR-PAM images using MEMS will help to visualize high-resolution superficial vasculatures as well as lower resolution deep vasculature, utilizing the full potential of high-resolution photoacoustic technology at high speed. The use of MEMS will help in the development of miniaturized handheld based devices for clinical imaging applications

Simultaneous OR-AR-PAM System

Laser Safety

Results and Discussion

Conclusions