Miniature RF coils offer new opportunities for interventional MRI

By Greg Freiherr

The commercial release at the RSNA meeting last month of Surgi-Visions's two miniature radio-frequency coils, one for the female urethra, the other for the esophagus, opens new possibilities for interventional MRI.

The single-use coils, being marketed under the product name Intercept, will likely promote the use of MRI in urologic and cardiologic studies.

"Cardiac MR is growing at a good clip and the esophagus coil provides a platform for seeing the aorta and back of the left atrium and left ventricle," said Sean M. Salmon, vice president of sales and marketing at Surgi-Vision. "The urethral coil provides a functional diagnosis of incontinence so physicians can better select therapy. Right now there is no way to get a clear idea of the problem."

The urethra coil supports capture of high-resolution images of the female urethral wall and may be useful in diagnosing and following the effectiveness of treatment designed to relieve urinary incontinence or destroy cancer. The esophageal coil allows circumferential imaging of the aorta and esophagus. With it, MRI can obtain data about heart and esophageal walls and the surrounding tissue, maximizing resolution in a small field-of-view.

Most sales of the coils will be made through GE Medical Systems, which has a distribution agreement with Surgi-Vision giving GE exclusive worldwide distribution rights to the coils. But the small privately held company, based in Columbia, MD, has retained the right to sell its products directly. Surgi-Vision has no plans to launch a major sales effort in the near future, however.

The two coils are the first members of a planned family of invasive coils. Another urethral coil, designed specifically for men, is in development. A vascular coil is also being developed as an enabling technology for MR-guided intervention to provide a close look at the vascular wall. This product could help generate information about plaque composition and tissues on the other side of an occlusion in the blood vessel. A third work-in-progress addresses the prostate and may help in staging and managing prostate cancer.

The Intercept urethral and esophageal coils are best suited for use with 1.5-tesla scanners. Patient access during the scan is not an issue, according to Salmon. Coils can be inserted prior to positioning the patient in the magnet, he said. Minor adjustments, if necessary, can be made remotely by the technologist during the procedure.

Higher field open scanners, however, could be convenient. Adapting the Intercept coils for use with these scanners is feasible.

"We just have to tune the interface box to the magnet," Salmon said.

Only two sites, Johns Hopkins Medical Institutions and Brigham and Women's Hospital, have used the invasive coils clinically. Other sites, including the Mayo Clinic, Stanford University, and Atlanta Cardiology Research Foundation, are negotiating with Surgi-Vision for the products. n