Electrothermal-MEMS-induced nonlinear distortion correction in photoacoustic laparoscopy

Abstract

Micro-electro-mechanical systems (MEMS) scanner has significant advantages of miniature size, fast response and high stability, which is particularly applicable to photoacoustic laparoscopy (PAL). However, tilt angle-voltage curve of electrothermal MEMS shows a nonlinear character, which leads to inevitable nonlinear distortion in photoacoustic imaging. To overcome this problem, a nonlinear distortion correction was developed for the high-resolution forward-scanning electrothermal-MEMS-based PAL. The adaptive resampling method (ARM) was introduced to adaptively calibrate the projection of non-uniform scanning region to match the uniform scanning region. The correction performed low time complexity and high portability owing to the adaptive capacity of distortion decomposition in the reconstruction of physical models. Compared with the sample structure, phantom experiments demonstrated that the distortion was calibrated in all directions and the corrected image provided up to 96.82% high structural similarity in local subset. Furthermore, ARM was applied to imaging the abdominal cavity of rat and the vascular morphology was corrected in real-time display within a delay less than 2 seconds. All these results demonstrated that the nonlinear distortion correction possessed timely and effective correction in PAL, which suggested that it had the potential to employ to any other electrothermal-MEMS-based photoacoustic imaging systems for accurate and quantitative functional imaging.

Spatial weight matrix in dimensionality reduction reconstruction for micro-electromechanical system-based photoacoustic microscopy

“…Considering that the COVID-19 pandemic is still a global problem, the experimental data for validation of this SWM are transplanted from our database, which includes the data from the PAL equipped with electrothermal MEMS [10] and the data from a photoacoustic pen equipped with electrostatic MEMS [9].…”

“…The imaging system used in this study was the same as that used in previous studies, as shown in Figs. 1 a and b [ 10 ]. The figure shows a system with the optical components annotated along the light path.…”

“…A MEMS mirror has the advantages of high-speed scanning, minimum power consumption, a comparatively small size, and light weight. Thus, it is suitable for a variety of OR-PAM instruments in rapid microscopic imaging [8], including a high-speed dual-view photoacoustic imaging pen [9], a MEMS scanning mirror enhanced photoacoustic laparoscope with an adaptive resampling method [10], and a combination of a MEMS scanning mirror and multimode fibers [11]. A MEMS mirror is selected for OR-PAM based on its intended application.…”

Miniature all-optical flexible forward-viewing photoacoustic endoscopy probe for surgical guidance

“…These and other applications often require a flexible miniature photoacoustic tomography probe that provides 3D images of the vasculature in a forward-viewing configuration. However, the majority of previously reported PAE probes are sideways-viewing [ 7 – 14 ] and of the few forward-viewing probes demonstrated so far, almost all operate in the optical resolution microscopy mode [ 15 , 16 ]. In this mode, a focused excitation laser beam is raster scanned over the target tissue to generate the photoacoustic waves.…”

“…In summary, a novel miniature flexible PA endoscopy probe has been demonstrated that enables high-resolution 3D imaging in the forward-viewing configuration. This approach to PA endoscopy offers several advantages over the previously reported probes based on piezoelectric and CMUT technologies [ 7 – 14 , 16 ]. These include a forward-viewing configuration, finer spatial sampling, and wider detection bandwidth than achievable with piezoelectric and CMUT receivers, an all-optical passive imaging head for safe endoscopic use, immunity to electromagnetic interference (EMI), and potential compatibility with magnetic resonance (MR) scanners.…”