Hybrid photoacoustic and ultrasound section imaging with optical ultrasound detection

Abstract

Journal of BIOPHOTONICSA setup is proposed that provides perfectly co-registered photoacoustic (PA) and ultrasound (US) section images. Photoacoustic and ultrasound backscatter signals are generated by laser pulses coming from the same laser system, the latter by absorption of some of the laser energy on an optically absorbing target near the imaged object. By measuring both signals with the same optical detector, which is focused into the selected section by use of a cylindrical acoustic mirror, the information for both images is acquired simultaneously. Co-registered PA and US images are obtained after applying the inverse Radon transform to the data, which are gathered while rotating the object relative to the detector. Phantom experiments demonstrate a resolution of 1.1 mm between the sections of both imaging modalities and a inplane resolution of about 60 mm and 120 mm for the US and PA modes, respectively. The complementary contrast mechanisms of the two modalities are shown by images of a zebrafish.Result of the dual-modality section imaging experiment on a zebrafish. Scale bar: 1 mm. The first row shows the photoacoustic (PA) and the laser ultrasound (LUS) section image. The second row shows the fusion image (FI) and the histological section.

Broadband miniature optical ultrasound probe for high resolution vascular tissue imaging

“…Whilst all-optical ultrasound images have previously been obtained [5][6][7][8], those in this study were significant in terms of the detail with which tissue microstructure was visualised, and the compactness of the probe with which they were acquired. The high performance of the probe in this study stemmed from a combination of the high ultrasound pressures transmitted by the optically absorbing film and the high sensitivity of the concave FP ultrasound sensor.…”

“…Additionally, it can be challenging to achieve wide transmission bandwidths and adequate wideband reception sensitivity with small piezoelectric elements. Optical methods for transmitting and receiving ultrasound are emerging as alternatives to their electrical counterparts [5][6][7][8]. They offer several distinguishing advantages including the potential to generate and detect the broadband ultrasound fields (tens of MHz) required for high resolution endoscopic imaging.…”

“…Whilst all-optical ultrasound images have been demonstrated previously [5][6][7][8], there is a need to miniaturise the optical designs in order to make them compatible with interventional devices. In this paper, we describe a novel miniature fiber optic probe that is based on the two concepts outlined above: a fiber optic transmitter that employs a CNT based absorbing film [12] for generating broadband ultrasound and a fiber-optic FP polymer sensor [21] for receiving it.…”

Combined photoacoustic, pulse-echo laser ultrasound, and speed-of-sound imaging using integrating optical detection

“…24 In addition to its broad bandwidth, another big advantage of this detector is its transparency for traversing sound waves. This feature enables hybrid PA and LUS section imaging by adding an additional acoustic reflector as proposed by Nuster et al 25 The surface of this cylindrical mirror is covered with a lightabsorbing layer, where focused sound waves are generated upon illumination.…”

Simultaneous three-dimensional photoacoustic and laser-ultrasound tomography

“…For simultaneous US and PA imaging the same laser pulse is used for illuminating an external absorber and the object under investigation. Nuster et al used this method for hybrid PA and US section imaging with focused detection to obtain coregistered 2D images [15]. Various researchers proposed setups for hybrid PA and LUStransmission imaging [16][17][18][19].…”