Augmented Reality Can Help Achieve Safer, More Efficient CT-Guided Ablations

Technology has the potential to reduce procedure time and radiation exposure

Brian Park, MD, MS
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Augmented reality (AR) is an emerging display technology with the ability to seamlessly merge virtual 3D objects with the real-world environment. With AR, 3D projections of entire cross-sectional imaging can be overlaid onto patients during procedures for virtual 3D intraoperative guidance.


These 3D projections can provide image-guided interventionalists enhanced visualization and spatial localization of tumors, which may increase the success of procedures, improve safety profiles, and reduce procedure times and radiation exposures.


“We have previously piloted remote volume rendering on an AR head-mounted display to project CT or MRI imaging as a virtual 3D volume and manually registered these volumes onto live patients during CT-guided ablations,” said Brian Park, MD, MS, a former electrical engineer and now an assistant professor of interventional radiology and biomedical engineering in the Dotter Department of Interventional Radiology at Oregon Health & Science University, Portland.


This is important because it provides the capability to generate virtual 3D volumes within seconds, permitting intraoperative scans to be projected immediately after acquisition. Other AR developments are limited to only using preoperative scans, which are typically performed with patients positioned on their back, which may be different from their positions during procedures.


“Accurately aligning, or registering, the 3D volumes onto patients can be very tedious and cumbersome, especially if performed manually,” Dr. Park said. Therefore, in his 2019 Dr. Alexander Margulis Siemens Healthineers/RSNA Research Fellow Grant, “Development of Intraoperative 3D Holographic Augmented Reality-assisted Navigation System for CT-guided Percutaneous Ablations,” Dr. Park and his team sought to find ways to both quickly generate virtual 3D volumes and register them accurately onto patients to have the ability to look directly inside patients on the CT table for guidance.

“AR has the potential to drastically change the way we visualize and interact with medical imaging during procedures, resulting in real tangible benefits for both patients and operators.”

Brian Park, MD, MS 

AI and Computer Vision to Supplement CT

For the study, Dr. Park and his team utilized AI and computer vision to automatically detect and track a commonly used CT grid. Various methods for aligning a 3D model onto the CT grid were evaluated across two institutions. Automated registration using AI and computer vision was the quickest and most accurate method of alignment with mean registration times under six seconds.


Based on the automated registration method, a prospective phantom trial was performed assessing CT-guided lesion targeting on an abdominal phantom with and without AR guidance using a commercially available head-mounted holographic device.  With AR guidance, operators were able to see a holographic 3D line projecting out from the target that represented the ideal path, or needle trajectory, to the target.


Eight operators, including medical students, residents, fellows, and attending physicians, performed a cumulative total of 86 needle passes. AR-assisted needle guidance resulted in halving the procedure time, needle re-directions and radiation dose along with minimizing inadvertent puncture of non-target objects. All operators performed better with AR-assisted guidance. Of particular note, medical students without any prior exposure to or experience with CT-guided procedures performed at the same level as experienced attendings with AR assistance.


Dr. Park was excited but not surprised from these findings.


“You don’t need a medical degree to follow a 3D line in space with an object,” Dr. Park said. “Inexperienced operators may feel more confident in performing better and more efficient ablations with this technology.”


Although the study never made it to trial on live patients, Dr. Park is optimistic that we will see more AR utilization in health care in the future.


“Who wouldn’t want useful information that is readily available to be conveniently displayed right in front of them?” he asked.


Improved Outcomes With Less Radiation

The ultimate goal of using AR during CT-guided ablations is to achieve improved outcomes with safer, more efficient image-guided interventions that require less radiation.


“AR has the potential to drastically change the way we visualize and interact with medical imaging during procedures, resulting in tangible benefits for both patients and operators,” Dr. Park said.


The funding provided by the R&E Foundation offered Dr. Park the opportunity to focus on this research during a busy clinical season.


“The acquisition and development of new technologies for research can be costly,” Dr. Park said. “The R&E Foundation grant helped offset these costs and provided a tremendous opportunity for me to work on my passion for combining medicine and engineering.”


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