Miniature MRI coil nears commercial launch

Technology could help MRI compete with cardiac cath

The first MRI coil small enough to be inserted in the esophagus and behind the heart has been cleared by the Food and Drug Administration and could be commercially available by the first of next year.

The endo-esophageal coil, developed by Columbia, MD-based Surgi-Vision and cleared by the FDA in September, is designed to deliver high-quality images of the esophagus, aorta, and heart. Company engineers are building the coils, which measure just 0.035 inches, for other probes, including one that might be threaded into the coronary arteries. Together, these products could help open cardiology to MRI diagnosis and therapy, according to Alan Sauber, vice president of operations at Surgi-Vision.

“Docs want to shed the lead; they want to get rid of all the issues about ionizing radiation,” Sauber said. “All that goes away with MRI.”

Inserted through the nose and down the esophagus, the current product comes within several centimeters of the aorta and heart wall. Resolution approaches 100 microns in tissues closest to the coil, even at frame rates of 30 or more per second, according to radiologists and cardiologists who have tested the device. They caution, however, that such resolution can be achieved only on a high-field, high performance scanner. Also, resolution falls off rapidly with increasing distance from the coil, according to tests conducted at Johns Hopkins Medical Institutions in Baltimore. Even so, resolution of 300 microns can be achieved in real-time imaging on tissue 4 to 5 cm away.

Coils designed for the coronary artery could deliver diagnostic information as good as or better than data coming from x-ray cardiac cath studies, according to Johns Hopkins cardiologist Dr. João A.C. Lima, who has evaluated prototypes of the coil technology (SCAN 3/3/99). In such applications, MRI would borrow a page from conventional medicine, as a catheter is threaded under MRI guidance into the coronaries. But instead of radio-opaque dyes, MRI coils traveling through the catheter would provide the means for visualization. Methods for getting these coils out of the laboratory and into the hands of mainstream practitioners still need to be established.

Surgi-Vision is now working out details for marketing and distributing the coil. One possibility could be the establishment of supply agreements with major OEM vendors. Sauber neither confirmed nor denied that such talks were under way, stating only that a plan for commercialization of the endo-esophageal coil could be in place by the end of November.

The company’s timing could not be better. Major MRI vendors are expected to highlight advances in cardiovascular imaging at the annual RSNA meeting at the end of November. Surgi-Vision will be at the RSNA meeting and, earlier in the month, at the annual meeting of the American Heart Association. Surgi-Vision will educate interventional cardiologists about progress in its coil technology, according to Sauber, focusing on the FDA-cleared product, as well as relevant products now in the pipeline. Radiologists will get a similar message a few weeks later. The company will be reaching out to the medical community at large, as well as the research community, according to Sauber.

“We’ve got a product,” he said. “Now we’re going to promote it.”

Radiologists and cardiologists have waged turf battles frequently over the past decade, particularly over intervention. According to Dr. Paul Bottomley, director of MR research and a professor of radiology at Johns Hopkins, no such squabbling occurs at his institution, however, where Surgi-Vision’s early coil technology was created and tested. Bottomley, who helped found Surgi-Vision and continues as a chief consultant to the company, says the technology should be viewed as a tool for advancing medical practice, not as part of a medico-political agenda.

“We are developing a new way of imaging,” Bottomley said. “The issue is not whether it’s used by radiology or cardiology. The issue is whether we have a new technology that can be applied for the benefit of patients.”

Surgi-Vision hopes to cross the boundaries of several medical specialties, opening new diagnostic and interventional capabilities. In addition to cardiac studies, future applications could include endorectal prostate examinations, as well as intravascular applications to visualize plaques or guide therapy. Sauber believes a decision on whether and when to move forward on one or possibly two coils will be made in the weeks ahead. An application for at least one new product, however, will probably be submitted to the FDA before the end of the year, he said.