In Vivo Demonstration of Photoacoustic Image Guidance and Robotic Visual Servoing for Cardiac Catheter-Based Interventions

Abstract

Cardiac interventional procedures are often performed under fluoroscopic guidance, exposing both the patient and operators to ionizing radiation. To reduce this risk of radiation exposure, we are exploring the use of photoacoustic imaging paired with robotic visual servoing for cardiac catheter visualization and surgical guidance. A cardiac catheterization procedure was performed on two in vivo swine after inserting an optical fiber into the cardiac catheter to produce photoacoustic signals from the tip of the fiber-catheter pair. A combination of photoacoustic imaging and robotic visual servoing was employed to visualize and maintain constant sight of the catheter tip in order to guide the catheter through the femoral or jugular vein, toward the heart. Fluoroscopy provided initial ground truth estimates for 1D validation of the catheter tip positions, and these estimates were refined using a 3D electromagnetic-based cardiac mapping system as the ground truth. The 1D and 3D root mean square errors ranged 0.25-2.28 mm and 1.24-1.54 mm, respectively. The catheter tip was additionally visualized at three locations within the heart: (1) inside the right atrium, (2) in contact with the right ventricular outflow tract, and (3) inside the right ventricle. Lasered regions of cardiac tissue were resected for histopathological analysis, which revealed no laser-related tissue damage, despite the use of 2.98 mJ per pulse at the fiber tip (379.2 mJ/cm 2 fluence). In addition, there was a 19 dB difference in photoacoustic signal contrast when visualizing the catheter tip

GPU implementation of photoacoustic short-lag spatial coherence imaging for improved image-guided interventions

“…This robustness is particularly advantageous when considering that the visual servoing algorithm initiates a search process after a series of unsuccessful segmentation events are recorded. 5 The probe centering and fiber tracking results [Figs. 8(a) and 9, respectively] indicate that the search process would be triggered more often with DAS than SLSC (see example provided in Video 1).…”

“…The segmentation performance with DAS, CPU-SLSC, and GPU-SLSC imaging was tested with in vivo data obtained from a previously completed experiment consisting of an optical fiber inserted in a porcine heart, as described in more detail in our previous publication. 5 To summarize the data acquisition procedure, the optical fiber was first inserted into a cardiac catheter, and then the fiber-catheter pair was guided to the right atrium of the heart. The fiber emitted a laser wavelength of 750 nm with a pulse energy of 2.98 mJ.…”

“…The channel data with added noise were then beamformed using DAS, CPU-SLSC, and GPU-SLSC, and photoacoustic signals were segmented using the algorithm described in our previous publication. 5 The locations of the segmented signals were compared with ground truth segmentations derived from corresponding in vivo channel data with no noise added. A failed segmentation was defined as either no segmentation result or no overlap of the segmented signal with the ground truth segmentation.…”

“…4 , 5 Photoacoustic imaging is achieved by transmitting pulsed light to a structure of interest, which absorbs the light, undergoes thermal expansion, and generates an acoustic response that is received by a conventional ultrasound probe. 6 – 8 This photoacoustic imaging technique was previously demonstrated for multiple applications that require surgery or interventions, such as visualization of brachytherapy seeds, 9 , 10 intravascular imaging, 11 cardiac catheter visualization, 5 fetal surgeries, 12 prostate surgeries, 13 and endonasal surgeries. 14 – 16 In these applications, structures of interest include blood vessels, nerves, drill tips, and catheter or needle tips.…”

“…14 – 16 In these applications, structures of interest include blood vessels, nerves, drill tips, and catheter or needle tips. 5 , 17 , 18 One or more optical fibers may be coupled to the tool, catheter, or needle tips to transmit the light pulses. 11 , 19 – 21 Alternatively, a fiber or fiber bundle may be operated independently to provide photoacoustic-based anatomical guidance in the absence of surgical tools.…”