Five-wavelength optical-resolution photoacoustic microscopy of blood and lymphatic vessels

Chao Liu,Jingyi Zhu,Jiangbo Chen,Yachao Zhang,Lidai Wang

doi:10.1117/1.ap.3.1.016002

Abstract

Optical-resolution photoacoustic microscopy (OR-PAM) has been developed for anatomical, functional, and molecular imaging but usually requires multiple scanning for different contrasts. We present five-wavelength OR-PAM for simultaneous imaging of hemoglobin concentration, oxygen saturation, blood flow speed, and lymphatic vessels in single raster scanning. We develop a five-wavelength pulsed laser via stimulated Raman scattering. The five pulsed wavelengths, i.e., 532, 545, 558, 570, and 620 / 640 nm, are temporally separated by several hundreds of nanoseconds via different optical delays in fiber. Five photoacoustic images at these wavelengths are simultaneously acquired in a single scanning. The 532- and 620 / 640-nm wavelengths are used to image the blood vessels and dye-labeled lymphatic vessels. The blood flow speed is measured by a dual-pulse method. The oxygen saturation is calculated and compensated for by the Grüneisen-relaxation effect. In vivo imaging of hemoglobin concentration, oxygen saturation, blood flow speed, and lymphatic vessels is demonstrated in preclinical applications of cancer detection, lymphatic clearance monitoring, and functional brain imaging.

Highlights

In vivo imaging of blood vessels and lymphatic vessels is important for monitoring physiological parameters and early diagnosing of fatal diseases.[1,2,3] The blood and lymphatic vessels are two sets of circulatory networks that have distinct but interdependent functions
Fiber-based optical delay switches the wavelengths within sub-microseconds, which reduces the misalignment in multi-wavelength imaging
The 532, 545, 558, and 570-nm wavelengths are suitable for blood vessel imaging, and the 620∕640-nm wavelength offers high contrast for lymphatic vessel imaging

Summary

Introduction

In vivo imaging of blood vessels and lymphatic vessels is important for monitoring physiological parameters and early diagnosing of fatal diseases.[1,2,3] The blood and lymphatic vessels are two sets of circulatory networks that have distinct but interdependent functions. Lymphatic vessels are found in most tissues and play an important role in many physiological processes.[4] The blood circulation supplies oxygen and nutrients, removes waste, and is highly associated with the lymphatic circulation. Recent research has shown that blood flow, local oxygen content, and lymphatic vessels are important factors in tumor growth and metastasis.[5,6,7,8,9,10,11,12,13,14] Simultaneous imaging of blood and lymphatic vessels is of great value in disease diagnosis and treatment.[3] Most existing bioimaging techniques are limited to either low spatial/temporal resolution or unable to simultaneously image multi-contrasts in the blood and lymphatic

Methods

Results

Conclusion