Performance characteristics of an interventional multispectral photoacoustic imaging system for guiding minimally invasive procedures

Abstract

Precise device guidance is important for interventional procedures in many different clinical fields including fetal medicine, regional anesthesia, interventional pain management, and interventional oncology. While ultrasound is widely used in clinical practice for real-time guidance, the image contrast that it provides can be insufficient for visualizing tissue structures such as blood vessels, nerves, and tumors. This study was centered on the development of a photoacoustic imaging system for interventional procedures that delivered excitation light in the ranges of 750 to 900 nm and 1150 to 1300 nm, with an optical fiber positioned in a needle cannula. Coregistered B-mode ultrasound images were obtained. The system, which was based on a commercial ultrasound imaging scanner, has an axial resolution in the vicinity of 100 μm and a submillimeter, depthdependent lateral resolution. Using a tissue phantom and 800 nm excitation light, a simulated blood vessel could be visualized at a maximum distance of 15 mm from the needle tip. Spectroscopic contrast for hemoglobin and lipids was observed with ex vivo tissue samples, with photoacoustic signal maxima consistent with the respective optical absorption spectra. The potential for further optimization of the system is discussed.

Ultrasonic Needle Tracking with a Fibre-Optic Ultrasound Transmitter for Guidance of Minimally Invasive Fetal Surgery

“…Future optimisations to the transmitter could include optical absorption surfaces that are domed or extended in length to achieve different angular transmission patterns. Optical absorbing coatings that are transmissive at certain wavelengths could be used for interventional PA imaging [13,19,20].…”

“…For PA imaging, pre-beamformed radiofrequency (RF) data from all of the transducer elements in the imaging probe were simultaneously sampled at 40 MS/s by a multi-channel data acquisition system (SonixDAQ, Analogic Ultrasound) and transferred to the US imaging system personal computer (PC). Conventional B-mode (pulse-echo) US image acquisition was performed immediately after PA image acquisition, as detailed in [13].…”

Synthetic-aperture based photoacoustic re-beamforming (SPARE) approach using beamformed ultrasound data

“…However, the option to use an FDAapproved clinical ultrasound system eases the transition of photoacoustic technology into the clinic. Potential applications include real-time in vivo photoacoustic visualization for brachytherapy monitoring [15,16], image-guided surgery [17,18], interventional photoacoustic tracking [19], multispectral interventional imaging [20], and cardiac radiofrequency ablation monitoring [21].…”

Photoacoustic-guided focused ultrasound for accurate visualization of brachytherapy seeds with the photoacoustic needle

“…3,6 Thus, PA imaging can complement US imaging for better visualization of brachytherapy seeds. 3,6,7 Considering the imaging depth required, the PA needle 8,9 with interstitial light delivery via a cutting percutaneous needle is generating much interest in imaging brachytherapy seeds. 7 A challenge in interstitial PA imaging of brachytherapy seeds is the presence of reflection artifacts caused by the high PA signal from the optical fiber/needle tip reflecting off the seeds as shown in Fig.…”