Flow imaging is an important technique in a range of disease areas, but estimating low flow speeds, especially near the walls of blood vessels, remains challenging. Pulsed photoacoustic flow imaging can be an alternative since there is little signal contamination from background tissue with photoacoustic imaging. We propose flow imaging using a clinical photoacoustic system that is both handhel...

The problem of determining a function from a subset of its spherical means has a rich history in pure and applied mathematics. Its connection with photoacoustic imaging has already been made abundantly clear in earlier chapters in this volume: when the sound speed νs in a medium is constant the pressure at time t and point r is expressed in terms of spherical means of the pressure, and its time...

Photoacoustic imaging is a unique modality that overcomes to a great extent the resolution and depth limitations of optical imaging while maintaining relatively high contrast. However, since many diseases will not manifest an endogenous photoacoustic contrast, it is essential to develop exogenous photoacoustic contrast agents that can target diseased tissue(s). Here we present a family of novel...

Accurate and efficient identification of nerves is of great importance during many ultrasound-guided clinical procedures, including nerve blocks and prostate biopsies. It can be challenging to visualise nerves with conventional ultrasound imaging, however. One of the challenges is that nerves can have very similar appearances to nearby structures such as tendons. Several recent studies have hig...

Photoacoustic imaging is a hybrid technique that shines laser light on tissue and measures optically induced ultrasound signal. There is growing interest in the clinical community over this new technique and its possible clinical applications. One of the most prominent features of photoacoustic imaging is its ability to characterize tissue, leveraging differences in the optical absorption of un...

Compressed sensing (CS) can recover sparse signals from undersampled measurements. In this work, we have developed an advanced CS framework for photoacoustic computed tomography (PACT). During the reconstruction, a small part of the nonzero signals’ locations in the transformed sparse domain is used as partially known support (PKS). PACT reconstructions have been performed with under-sampled in...

Fluorescent nanodiamonds (FNDs) have drawn much attention in recent years for biomedical imaging applications due to their desired physical properties including excellent photostability, high biocompatibility, extended far-red fluorescence emission, and ease of surface functionalization. Here we explore a new feature of FNDs, i.e. their photoacoustic emission capability, which may lead to poten...

Photoacoustic tomography (PAT) is a hybrid imaging technique that offers similar medical potential as ultrasound and optical imaging. Although efforts to innovate Photoacoustic scanners have been scarce, newer developments such as k-Wave will enable their optimal imaging capability. Despite k-Wave’s ability to simulate PAT, few researchers utilize this technology. Thus, this project explored th...

A targeted gold nanoparticle has been developed as a contrast agent for photoacoustic medical imaging. We have studied cancer cell targeting by antibody conjugated gold nanorods for high contrast photoacoustic imaging. By changing the aspect ratio of the elongated “rod” shape of the gold nanoparticle, its plasmon peak absorption wavelength can be tuned to the near IR 700–900 nm for an increased...

A real-time photoacoustic imaging system is designed and built. This system is based on a commercially available ultrasound imaging system. It can achieve a frame rate of 8 frames/sec. Vasculature in the hand of a human volunteer is imaged, and the resulting photoacoustic image is combined with the ultrasound image. The real-time photo acoustic imaging system with a hybrid ultrasound probe is d...