Comparison of flexible array with laparoscopic transducer for photoacoustic-guided surgery

Abstract

Photoacoustic imaging has recently demonstrated strong viability to visualize tool tips and assist with guidance during surgeries and interventional procedures. The more conventional rigid ultrasound transducers that can be used to sense photoacoustic signals require applied pressure for complete tissue contact when placed on curved surfaces. However, emerging flexible arrays are better suited to conform to different anatomical geometries. This work presents photoacoustic images acquired with a conventional laparoscopic transducer and a more flexible transducer array when placed in contact with surfaces of different curvatures, providing quantitative comparisons of image quality and transducer characterization. An optical fiber was inserted and translated within hemispherical phantoms along each transducer's elevation dimension to estimate the corresponding elevation field-of-view (FOV). A wider elevation FOV was measured with the flexible array, which indicates decreased elevation localization certainty, but increased ability to find tool tips when compared to the laparascopic probe. The average target depth accuracy was 99.36% with the flexible array and 95.05% with the laparoscopic probe, due to the differences in pressure required to maintain acoustic contact. Image contrast and signal-to-noise ratios were greater with the flexible array than with the laparoscopic probe. These properties of the flexible array enhance its desirability for photoacoustic-guided surgical interventions.

Flexible array curvature and sound speed estimations with a maximum spatial lag-one coherence metric

“…We previously presented a flexible array for photoacoustic-guided interventions, which implemented delayand-sum (DAS) beamforming in simulation and phantom studies, 4,5 and compared the image quality with that of a conventional linear transducer. 6 This work was based on known sound speeds and array curvatures. When array curvatures are unknown, possible solutions include deep neural networks 7 for transducer geometry parameter estimations, amplitude-based differentiable beamforming with a phase error loss, 8 or optimizing the average pixel brightness in a short-lag spatial coherence (SLSC) ultrasound.…”

Ultrasound Imaging with Flexible Array Transducer for Pancreatic Cancer Radiation Therapy

“…The flexible array transducer is a promising design that can address user dependency and induced anatomical changes of the conventional US transducer [ 46 , 47 , 48 ]. The flexible array transducer is a thin US transducer that can be attached to the body surface and adapt to different geometries [ 49 , 50 ].…”