Video-rate dual-modal photoacoustic and fluorescence imaging through a multimode fibre towards forward-viewing endomicroscopy

Abstract

Multimode fibres (MMFs) are becoming increasingly attractive in optical endoscopy as they promise to enable unparallelled miniaturisation, spatial resolution and cost. However, high-speed imaging with wavefront shaping has been challenging. Here, we report the development of a video-rate dual-modal photoacoustic (PA) and fluorescence microscopy probe with a high-speed digital micromirror device (DMD) towards forward-viewing endomicroscopy. Optimal DMD patterns were obtained using a real-valued intensity transmission matrix algorithm to raster-scan a 1.5 m-diameter focused beam at the distal fibre tip for imaging. The PA imaging speed and spatial resolution were varied from 2 to 57 frames per second and from 1.7 to 3 m, respectively. Further, high-fidelity PA images of carbon fibres and mouse red blood cells were acquired at unprecedented speed. The capability of dual-modal imaging was demonstrated with phantoms. We anticipate that with further miniaturisation of the ultrasound detector, this probe could be integrated into medical needles to guide minimally invasive procedures.

Characterizing a photoacoustic and fluorescence imaging platform for preclinical murine longitudinal studies

“…Given the complementary nature of PA and FL imaging, prototype imaging systems that integrate these technologies have been previously investigated. 31 – 33 While these imaging systems highlight the advantages of combining PA and FL imaging, they are limited to providing individual 2D images of the subject. The TriTom, however, is uniquely designed to simultaneously collect volumetric PA (azimuthal frames) and FL (multiangle planar frames) data with a temporal resolution limited only by the maximum speed of the rotational motor.…”

“…Here, we introduce a preclinical imaging system, the TriTom, that integrates PA and FL imaging to capitalize on the strengths of both modalities and mitigate the disadvantages of either technique. Compared to other combined PAI and FLI systems, 31 – 33 our imaging platform achieves coregistered PA tomography (PAT) and FL molecular tomography (FMT) to enable 3D volumetric imaging with high-resolution and high molecular sensitivity. Additionally, the TriTom acquires whole-body in vivo azimuthal PA frame data and planar optical data simultaneously, allowing for the temporal co-registration of the reconstructed PAT and FMT volumes.…”

All-optical multimode fibre photoacoustic endomicroscopy with scalable spatial resolution and field-of-view

“…Early forward-viewing PAEs employed multi-core coherent fibre bundles with imaging being accomplished by raster-scanning a focused laser beam between the distal ends of the individual cores [4]. Recently, multimode fibres (MMFs) were reported in forward-viewing PAE and a focused laser beam was delivered through a MMF using wavefront shaping [6], leading to an improved spatial resolution, and reduced costs and probe sizes compared to multi-core fibre bundles. In this work, we developed a high-speed, all-optical photoacoustic endomicroscopy (PAEM) probe using a digital micromirror device for wavefront shaping.…”

Adaptive Enhancement of Acoustic Resolution Photoacoustic Microscopy Imaging Via Deep CNN Prior

“…The PAI system can be categorized into two major implementations, i.e., PA computed tomography (PACT) and PA microscopy (PAM). The PACT system utilizes multi-element ultrasound transducer arrays to realize real-time (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) and deep penetrate (up to ~5 cm) imaging capability [4], however, it is hard to acquire high resolution imaging in finer structures [5]. In contrast, the PAM system employs single-element ultrasound transducer to receive the acoustic signal in each scanning point.…”

“…However, the acoustic focusing spot is usually ten times wider than optical focusing spot, which result in the inferior spatial resolution (45 μm ~ 1.16 mm) [7][8][9][10][11][12]. Nevertheless, the low spatial resolution of AR-PAM imaging also loosens the constraint to the scanning step size (15~100 μm), which speed up the scanning process when the same area is imaged [13][14]. Thereby except for the low imaging lateral resolution, AR-PAM possesses superior penetration depth and less scanning time over the OR-PAM modality.…”