Motionless volumetric photoacoustic microscopy with spatially invariant resolution

Abstract

Photoacoustic microscopy (PAM) is uniquely positioned for biomedical applications because of its ability to visualize optical absorption contrast in vivo in three dimensions. Here we propose motionless volumetric spatially invariant resolution photoacoustic microscopy (SIR-PAM). To realize motionless volumetric imaging, SIR-PAM combines two-dimensional Fourier-spectrum optical excitation with single-element depth-resolved photoacoustic detection. To achieve spatially invariant lateral resolution, propagation-invariant sinusoidal fringes are generated by a digital micromirror device. Further, SIR-PAM achieves 1.5 times finer lateral resolution than conventional PAM. The superior performance was demonstrated in imaging both inanimate objects and animals in vivo with a resolution-invariant axial range of 1.8 mm, 33 times the depth of field of the conventional PAM counterpart. Our work opens new perspectives for PAM in biomedical sciences.

Low Temperature-Mediated Enhancement of Photoacoustic Imaging Depth

“…There are other methods for deep PA imaging such as optical clearing of bio-tissues. In this method, the scattering coefficient and the degree of forward scattering of photons are manipulated, by administering some chemicals to increase the light penetration inside the tissue [46][47][48]. This method is invasive and cannot easily be translated to the clinic [46].…”

Optical synthetic sampling imaging: Concept and an example of microscopy

“…Recent developments in single-pixel imaging techniques provide a solution for reconstructing a digital image without using a 2D image sensor [6][7][8][9][10][11][12][13][14]. Single-pixel imaging techniques use a group of illumination patterns (e.g., Hadamard or Fourier basis patterns) generated by a spatial light modulator (SLM) to encode the 2D spatial information of an object into a one-dimensional (1D) time-varying intensity signals [15][16][17][18][19][20][21][22], and then use a spatial non-resolved detector to collect the time-varying light intensity signals. Clearly, the spatial information of the object is sampled by the illumination patterns.…”

<italic>In vivo</italic> optical imaging of brain activity

“…(a) Fluorescence excitation and collection in transparent and scattering tissues (take point scanning as an example) [8] ; (b) schematic diagram of the size and location of each brain region in the mice (The Gene Expression Nervous System Atlas (GENSAT) Project, http://www.gensat.org/imagenavigator.jsp?imageID=34298); (c) light scattering properties of different biological tissues and tissue phantom [4] ; (d) absorption spectra of water in visible and near-infrared band [4] 焦, 增强多光子效应, 降低得到同样荧光信号所需照 [11] ; (b), (c) 在NIR-IIb窗口对小鼠脑血管实时成像 [12] ; (d) 光声成像. SIR-PAM与 传统光声显微镜的比较 [13] ; (e) 利用SIR-PAM和传统光声显微镜对斑马鱼胚胎进行在体成像 [13] ; (f) 自适应光学的基本模型 [14] ; (g) 自聚焦透镜 示意图 [15] Figure 2 Deep brain imaging techniques. (a) In vivo three-photon imaging of neurons in mice brain [11] ; (b), (c) real-time imaging of mouse cerebrovascular vessels at the NIR-IIb window [12] ; (d) photoacoustic imaging.…”

“…(a) In vivo three-photon imaging of neurons in mice brain [11] ; (b), (c) real-time imaging of mouse cerebrovascular vessels at the NIR-IIb window [12] ; (d) photoacoustic imaging. Comparison of SIR-PAM with conventional photoacoustic microscopy [13] ; (e) in vivo imaging of zebrafish embryos using SIR-PAM and conventional photoacoustic microscopy [13] ; (f) a basic model of adaptive optics [14] ; (g) schematic of GRIN lens [15] NIR-II, 1000~1700 nm),…”

“…此外, 由于NIR-IIb波段的生物组织自发荧光 极少, 这也有利于成像信噪比的提高 [19] . [12,13,23] . 近红外二区荧光成像技术可以对小鼠 脑血管进行深层高分辨活体成像, 成像深度在小鼠 头皮和颅骨完整的情况下可以达到2.8 mm, 横向分 辨率可以达到3~4 μm [18] .…”