Catheter takes MR inside the body to detect plaque

MR manufacturers responded to claustrophobic patients by developing open scanners. Researchers in Israel have gone one step further: They've developed an MR scanner that enters the patient, rather than vice versa.

TopSpin Medical has devised a miniature handheld probe that incorporates all magnetic field sources and delivers high-resolution MR images. The disposable intravascular MRI catheter is intended for interventional cardiologists. Its primary application is to detect vulnerable coronary plaque.

"It is known that 70% of acute coronary syndromes are caused by vulnerable plaques, which are not angiographically significant and are currently undetectable by available imaging tools. Using the intravascular MRI catheter in a cardiac catheterization procedure will allow the detection of lipid-rich vulnerable plaques, characterization of plaque composition and geometry, and therapy guidance," said Eyal Kolka, senior vice president of business development for TopSpin.

Advantages of the technique include its low cost ($1000 and no expensive external setup), elimination of motion artifacts, accessibility to the patient during the procedure, compatibility with existing interventional tools, and resolution and diffusion contrast capabilities that are unattainable by conventional clinical MR imaging, according to Kolka.

The intravascular MRI catheter is stabilized vis-a-vis the arterial wall by the gentle inflation of a low-pressure (up to 1 atmosphere) side balloon, thereby achieving a resolution of 100 microns (0.1 millimeter). The catheter has about three to five times better resolution than state-of-the-art cardiac MR scanners, which achieve 300 to 500 microns (0.3 to 0.5 millimeter).

Other potential applications include detection and staging of prostate cancer, imaging of tumors in the colon, lung, and breast, and imaging of the peripheral vasculature, Kolka said. Clinical trials have begun in Europe to assess the safety and performance of the intravascular MRI catheter, and the device is expected to be released in 2005.