An all-optical Ultrasound imaging system has made possible live imaging from within the heart during keyhole surgery. This is a massive improvement over the current practice where surgeons rely on external ultrasound and preoperative imaging data.
A team from Queen Mary University of London (QMUL) and University College London (UCL) performed heart surgery in pigs utilizing the new imaging system comprising a cardiology needle tip that captures high-resolution images at a distance of 2.5cm from the needle. The imaging needle has a minute embedded optical fiber for transmission of light that generates ultrasonic pulses. These pulses upon reflection off the soft tissues are detected by a second optical fiber in the needle housing.
A mesh of carbon nanoparticles covered with silicon is placed on the tip of the optical fiber. An ultrasound wave due to photoacoustic effect is produced when pulsed light from the fiber is absorbed by carbon nanoparticles. Polymer optical microresonators facilitate detection of the small scale reflected ultrasound waves. The exceptionally high speed of the ultrasound emission and detection leads to unmatched resolution of the images (as fine as 64 microns) and permits real-time tracking of the motion of heart valves and walls.
According to Dr. Malcolm Finlay, study co-lead and consultant cardiologist at QMUL and Barts Heart Centre, the new method is ideal for surgery on small tissue targets. The new imaging system may also have potential use for applications such as in-womb surgery. Plans for the system’s application for clinical use are currently underway.