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Photoacoustic imaging can achieve high-resolution three-dimensional visualization of optical absorbers at penetration depths ~ 1 cm in biological tissues by detecting optically-induced high ultrasound frequencies. Tomographic acquisition with ultrasound linear arrays offers an easy implementation of single-side access, parallelized and high-frequency detection, but usually comes with an image quality impaired by the directionality of the detectors. Indeed, a simple translation of the array perpendicularly to its median imaging plane is often used, but results both in a poor resolution in the translation direction and in strong limited view artifacts. To improve the spatial resolution and the visibility of complex structures while keeping a planar detection geometry, we introduce, in this paper, a novel rotate-translate scanning scheme, and investigate the performance of a scanner implemented at 15 MHz center frequency. The developed system achieved a quasi-isotropic uniform 3D resolution of ~170 um over a cubic volume of side length 8.5 mm, i.e. an improvement in the resolution in the translation direction by almost one order of magnitude. Dual wavelength imaging was also demonstrated with ultrafast wavelength shifting. The validity of our approach was shown in vitro. We discuss the ability to enable in vivo imaging for preclinical and clinical studies., 43 pages, 5 figures

Brain treatment with High Intensity Focused Ultrasound (HIFU) can be achieved by multichannel arrays through the skull using time‐reversal focusing. Such a method requires a reference signal either sent by a real source embedded in brain tissues or computed from a virtual source, using the acoustic properties of the skull deduced from CT images. This noninvasive computational method allows precise focusing, but is time consuming and suffers from unavoidable modeling errors which reduce the accessible acoustic pressure at the focus in comparison with real experimental time‐reversal using an implanted hydrophone. Ex vivo simulations with a half skull immersed in a water tank allow us to reach at low amplitude levels a pressure ratio of 83% of the reference pressure (real time reversal) at 1MHz. Using this method to transcranially focus a pulse signal in an agar gel (model for in vivo bubble formation), we induced a cavitation bubble that generated an ultrasonic wave received by the array. Selecting the 1MHz...