GPS-like tracking aids in surgery safety, spares radiation doses

Electromagnetic tracking guidance during CT-guided liver biopsies reduced the number of scans needed and reduced patient radiation, according to a study published in this month’s American Journal of Roentgenology.

Using imaging to help guide percutaneous procedures has replaced surgical biopsy whenever possible, according to study authors Edward Kim, MD, with Mount Sinai Medical Center in New York City, and colleagues. They noted that while each modality (ultrasound, CT or MRI) has its benefits and drawbacks, electromagnetic tracking systems show the real-time location of the tracked instrument by using technology similar to a car’s global positioning system.

“The purpose of this study is to evaluate the effect of electromagnetic tracking assistance on nonfluoroscopic CT–guided liver biopsies with respect to the number of intraprocedural scans, effective radiation dose, number of needle manipulations, and procedure time from skin-stick to the target lesion,” the authors wrote.

For the study, the researchers selected 50 patients with lever lesions referred for biopsy who were randomly assigned to groups that had the CT-guided liver biopsy with and without electromagnetic tracking.

They found that electromagnetic tracking was an effective tool in aiding CT-guided liver biopsies—it reduced the number of scans during the procedure, radiation dose to the patient and the number of needle manipulations, though no adverse events were observed in either of the study groups.

Scans needed during the procedures dropped by 45 percent in the cohort using the electromagnetic tracker, a statistically significant reduction in effective radiation dose that equated to a radiation savings of approximately three unenhanced CT scans of the head or one unenhanced scan of the body.

The use of the tracking device also resulted in 64 percent less manipulations—fewer instrument manipulations can mean less chance for mistakes.

“When targeting lesions that are in close proximity to vital structures, such as the heart or major blood vessels, fewer instrument manipulations could translate into a lower rate of complications,” Kim and colleagues wrote. “For example, an increased number of pleural punctures during CT-guided lung biopsy has been shown to result in a higher risk of pneumothoraces.”

“The effectiveness and potential applications for electromagnetic tracking systems have been investigated in phantom and animal models, as well as limited clinical practice. The existing research has shown electromagnetic tracking to be accurate and to provide useful procedural information