3D photoacoustic fluctuation imaging provides visibility artefacts removal and enhanced contrast. Simultaneous implementation with ultrasound doppler imaging

Abstract

Photoacoustic imaging (PAI) provides optical contrast at depth beyond the optical transport mean free path. From the generation of ultrasound by light absorption, images can be reconstructed at the acoustic resolution ( 100 μm) with a penetration of a few cm. The design of imaging systems often leads to limited view artifacts, where a part of the information needed for a complete reconstruction of the objects is missing. We theoretically show that a dynamic approach based on the analysis of fluctuations induced by blood flow can suppress visibility artefacts. We demonstrate the performance of 3D Photoacoustic Fluctuation imaging (PAFI) using a spherical array with limited number of channels (256 elements, 8 MHz) in the chicken embryo model. Due to the low number of channels, standard PAI reconstructions additionally suffer from a poor contrast, which is enhanced by 2 to 3-fold using PAFI. We present an implementation of simultaneous PAFI and Ultrasound Power Doppler and present some results with coupled flow direction evaluations and optical contrast. Photoacoustic fluctuation imaging overcomes many limitations of conventional imaging and will be further evaluated for in-vivo imaging.