Instrument navigation tool reduces radiation, required images for fluoroscopy procedures

A new image modifier that shows real-time movement of an instrument during surgery reduces radiation and the time required to perform procedures required by traditional fluoroscopy, according to a May 7 study published in the American Journal of Roentgenology.

The modifier, ultralow radiation imaging coupled with image enhancement and instrument tracking (ULR-IE/IT), reduced the total time to localize an instrument by more than 30% and cut radiation exposure by more than 90% compared to C-arm fluoroscopy.

Minimally invasive surgery offers well-documented benefits compared to open dissection, but with it comes certain dangers, wrote Timothy Y. Wang, MD, of the department of neurological surgery, Duke University Medical Center in Durham, North Carolina, and colleagues.

“Inherent to minimally invasive procedures, however, is the lack of direct anatomic visualization,” the researchers added. “Therefore, surgeons must rely on intraoperative imaging, generally accomplished with C-arm fluoroscopy, to assess patient anatomy and instrument positioning. This reliance has increased radiation exposure to both surgeon and patient.”

Wang and colleagues set out to study a ULR-IE/IT package, analyzing its radiation output and accuracy compared to standard C-arm fluoroscopy at a single-institution.

Five physicians completed 23 trials in which they were asked to identify the ideal location for instrumentation in spinal, orthopedic, pain and physiatric procedures and subsequently place an instrument in that location in a cadaver with and without ULRI-IE/IT assistance. For the nine procedures—ranging from percutaneous pedicle screw insertion to foramen ovale ablation—use of assistance was randomly assigned.

For each procedure the researchers measured radiation exposure, time to place the instrument and the number of images needed to achieve accurate positioning.

Without the use of ULR-IE/IT, the total time to localize the instrument was 31.2% longer in all cases. The imaging aid helped reduce the total number of images needed per case by 74.8% and radiation exposure by 91.8%.

Additionally, physicians who used ULRI-IE/IT successfully placed the instrument on the first attempt in 82.6% of trials compared to a mean of 4.65 images needed for C-arm fluoroscopy.

“To our knowledge, this is the first human study quantifying the reduction of radiation, time, and image number for ULRIIE/IT,” the authors wrote. “This study included physicians from five specialties performing a total of 23 procedures, making the process we studied the single most widely applicable ultralow radiation instrument tracking technology currently available.”

The researchers cited many limitations to their study, including a lack of controlled randomization. Their results, however, still suggest reproducibility with the proper controls, they noted.

Despite this, and other limitations, Wang et al. wrote ULRI-IEE/IT should be considered as an option during minimally invasive surgery.

“Given the known harmful effects of radiation exposure, the use of the ULRI-IE/IT technology should be considered for minimally invasive spinal procedures and other fluoroscopy-intensive interventional procedures,” the authors concluded.