In vivo deconvolution acoustic-resolution photoacoustic microscopy in three dimensions

Abstract

Acoustic-resolution photoacoustic microscopy (ARPAM) provides a spatial resolution on the order of tens of micrometers, and is becoming an essential tool for imaging fine structures, such as the subcutaneous microvasculature. High lateral resolution of ARPAM is achieved using high numerical aperture (NA) of acoustic transducer; however, the depth of focus and working distance will be deteriorated correspondingly, thus sacrificing the imaging range and accessible depth. The axial resolution of ARPAM is limited by the transducer's bandwidth. In this work, we develop deconvolution ARPAM (D-ARPAM) in three dimensions that can improve the lateral resolution by 1.8 and 3.7 times and the axial resolution by 1.7 and 2.7 times, depending on the adopted criteria, using a 20-MHz focused transducer without physically increasing its NA and bandwidth. The resolution enhancement in three dimensions by D-ARPAM is also demonstrated by in vivo imaging of the microvasculature of a chick embryo. The proposed D-ARPAM has potential for biomedical imaging that simultaneously requires high spatial resolution, extended imaging range, and long accessible depth.

In vivo blind‐deconvolution photoacoustic ophthalmoscopy with total variation regularization

“…Compared with the conventional PAOM (Figure A), both BD and BDTV operations produce the microvessel images at better lateral resolution in Figure B,C. Note that the microvessels are visually dimmer after the BD operation alone (Figure B) than those from the BDTV operation (Figure C), which is partially caused by an uneven enhancement to the PA signals in the region of microvascular imaging . Additionally, because the tenuous retinal microvessels have the relatively poor imaging SNR, the noise amplification tends to occur for the BD iteration operation without a regularizing constraint .…”

“…Alternatively, the blurred imaging can be restored through deconvolution algorithm without physically modifying optical system. To date, the computational approach is adopted for enhancing in vivo photoacoustic microscopy (PAM) . Most deconvolution methods, such as Richardson‐Lucy (RL) deconvolution and Wiener Filtering, require a prior knowledge of the point spread function (PSF) of the imaging system, which is always impractical for in vivo microscopic imaging.…”

A frequency‐domain non‐contact photoacoustic microscope based on an adaptive interferometer

“…Most widely adopted PAM methods employ nanosecond or picosecond laser pulses to generate the PA signals and broadband ultrasound transducers to detect these signals. In acoustic-resolution PAM (AR-PAM) [6][7][8], diffuse optical radiation is used to generate the signals, while a focused transducer is used as the detector. Because signals are generated using diffused light, images can be obtained as deep as several millimeters.…”

Review of Laser-Generated Ultrasound Transmitters and Their Applications to All-Optical Ultrasound Transducers and Imaging

“…Thus, it was not widely presented in the commercial industry [83]. Piezoelectric transducers still dominated the majority of ultrasound-related applications and do the same nowadays [84,85]. In the last decade, due to the advancement of material sciences and fabrication technologies, exciting progress has been made in developing high-performance optical-based ultrasound transmitters as well as receivers.…”