Enhancement of photoacoustic microscopy by using a non-negative constrained pulse decomposition method

Abstract

According to the physical mechanism of photoacoustic excitation, we demonstrate that the signals detected by a photoacoustic microscopy can be considered as the superposition of a series of pulses with non-negative weight. Based on this factor, we decompose the photoacoustic signals as a series of basis and employ a non-negative constrained least squares criterion to determine their weights. Since the signal components are highly correlated with the basis but noise is not, the process will keep the signal components, but remove the noise and finally enhance the image. Phantom and in vivo animal experiments validate this method.

Non-invasive and low-artifact in vivo brain imaging by using a scanning acoustic-photoacoustic dual mode microscopy

“…AR-PAM breaks the limitation of optical diffusion and provides acoustic-resolution (a few tens to hundreds of micrometers) in deep tissue, which promises it a very wide range of applications, such as cancer detection, [11,12] in vivo brain imaging of small animals, [13][14][15][16][17] flow velocity monitoring, [18][19][20] and so on. [21][22][23][24][25][26][27][28][29][30][31][32] However, AR-PAM still faces the challenges of imaging through inhomogeneous multilayered media. When imaging optical absorbers below several acoustically inhomogeneous layers, the acoustic impedance mismatch between these layers could cause multiple reflections of PA signals.…”

Tunable spatiotemporal resolution photoacoustic microscopy by combining quasi-periodic scanning and register-fusion algorithm

“…PAM achieves a rich optical contrast with 100% sensitivity; moreover, it exhibits good biological safety owing to its nonionizing radiation, and can sensitively reveal structural and functional information of biological tissues. PAM has great application potential in biomedicine fields, including organology, 2) histology, [3][4][5] cytology, [6][7][8] vascular biology, [9][10][11][12][13][14][15] oncology, [6][7][8][9][10][11][12][13][14][15][16][17][18] neuroscience, 19,20) ophthalmology, 21,22) stomatology, 23,24) and dermatology. 25) PAM imaging usually relies on a point-by-point scanning scheme.…”

“…The spatial resolution and temporal resolution of a PAM are both highly related to the design of the scanning path. Theoretically, the spatial resolution in the lateral direction of a PAM depends on the size of the optical focus (opticalresolution PAM) [8][9][10]13,14,18,24,28) or the acoustic focus (acoustic-resolution PAM). 2,3,13,17,20,25) However, if the scanning step size is larger than the laser spot or acoustic focus, the practical spatial resolution of the image depends on the scanning line spacing.…”

“…Theoretically, the spatial resolution in the lateral direction of a PAM depends on the size of the optical focus (opticalresolution PAM) [8][9][10]13,14,18,24,28) or the acoustic focus (acoustic-resolution PAM). 2,3,13,17,20,25) However, if the scanning step size is larger than the laser spot or acoustic focus, the practical spatial resolution of the image depends on the scanning line spacing. In this situation, the term "resolution" is denoted as the pixel size of the image, depending on the sampling, but not the optical resolution of the system.…”