An all-optical, forward-viewing, optical-resolution photoacoustic endomicroscopy probe was developed for guiding minimally invasive procedures. The probe comprises a multimode fibre for the delivery of excitation laser via wavefront shaping, and a fibre-optic ultrasound sensor based on a plane-concave microresonator at the tip of a single-mode fibre. High-resolution photoacoustic microscopy images of mouse red blood cells and mouse ear vasculature were acquired, and the high scalability of the probe in terms of field-of-view and spatial resolution was demonstrated. The ultrathin photoacoustic endomicroscopy probe promises to guide minimally invasive surgery by providing both molecular and microstructural information.
Accurate identification of the interventional medical device during ultrasound-guided minimally-invasive procedures is of critical importance. A real-time 3D needle tracking system has been developed that utilises a fiber-optic, photoacoustic US transmitter integrated into the needle tip and a custom 2D, 4x4 receiver array attached to a clinical US imaging probe. Ultrasound signals received by the array are used to determine the location of source, which is then registered to the imaging probe and visualised. During initial laboratory measurements of tracking accuracy, the mean displacement between tracked and true distances from the array face was 0.8 ± 0.8 mm.
We have developed a clinically compatible, real-time ultrasound needle tracking system (UNT) that can be appended to a clinical ultrasound system, superimposing a crosshair onto the ultrasound image at the needle tip position. The UNT was developed under the ISO 13485 Medical Devices quality standard for deployment in the clinic. During handheld ultrasound guidance, the location of the needle tip within the imaging plane is determined from the acoustic signals received by an embedded fibre-topic hydrophone. Assessment of tracking accuracy found that the mean distance between tracked and true positions was 0.7 ± 0.4 mm with a repeatability of 0.3 ± 0.2 mm.
Ultrasound computed tomography offers to be a transformative breast imaging technology; however, quantitative measurement and artefact-free reconstruction of the diagnostically important property of acoustic attenuation has proven to be a challenge. The UK’s National Physical Laboratory (Teddington, UK) have developed a prototype ultrasound computed tomography system which utilises a novel sensor technology specifically designed for quantitative acoustic attenuation tomography. This scanning system, with its phase-insensitive receiver, has been used to generate 2D and 3D quantitative images of the acoustic attenuation of commercially-available and bespoke breast phantoms made by CIRS (Norfolk, VA, USA). The acoustic attenuation measurements and images obtained from the system were evaluated in comparison to acoustically characterised phantom materials and Xray computed tomography imagery. The images, while generated using a relatively fast and simple reconstruction method, were found to be less susceptible to artefacts common to acoustic attenuation tomography.
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