Philips plans dual-modality suite at UC San Francisco

An advanced concept in vascular imaging will be up and running in late October at the University of California, San Francisco when its state-of-the-art Philips MR interventional suite is completed.

The modalities will be installed in adjacent earthquake-proof rooms that can turn into one interventional MR/vascular x-ray suite. A specially designed patient table will slide between the rooms on tracks.

"Philips' experience in merging x-ray and MR imaging technology, coupled with UCSF's vast expertise and dedication in clinical MR research, will help to develop MR-guided endovascular work in the next five years," said Philips' MR global marketing director, Jacques J. Coumans, Ph.D.

According to Dr. Charles Higgins, MRI chief at UCSF, the suite will be used to perform minimally invasive endovascular procedures, in contrast to Boston's Brigham and Women's Hospital and the University of Minnesota, where MRI is used mainly to guide neurosurgical procedures.

"What we anticipate is guiding and perhaps doing minimally invasive surgery in the MR environment," said Higgins.

The major imaging components are a 1.5-tesla Gyroscan Intera I/T MRI scanner and an Integris V5000 vascular x-ray system, both from Philips.

Coumans said that Philips is interested in exploring the potential of MR to characterize coronary artery plaque. According to Higgins, however, coronary procedures are a long-range goal.

"What we are more interested in is characterizing plaque in other vessels first. That is not to say that we will not be doing coronaries, but that is much more difficult and we have to see the feasibility of using this approach for characterizing atherosclerotic plaque in other more acceptable vessels like the aorta and the carotid arteries," Higgins said.

The university has three immediate goals. The first is to perform correlative studies comparing MR angiography with conventional x-ray angiography.

"There have been so many advances in MR angiography in the last few years we want to compare them in the same setting," said Dr. Tim Roberts, UCSF's scientific director of interventional MRI. "That's why it's nice to be able to slide the same patient between the two environments."

Creating a special table that could move easily between the two rooms was just one of the technical obstacles Philips had to overcome to pass earthquake inspection in California. The other was the special shielding door between the two units.

"No one has ever had a requirement for a sliding door that was copper shielded for the MR environment and lead-lined for the x-ray environment," said Roberts.

The second goal, according to Higgins, is to evaluate MR as a complement to x-ray angiography.

"In the x-ray angiography lab, the patient would undergo whatever procedure was necessary to open up the artery causing the stroke or myocardial infarction," he said. "Then the patient would be brought into the MR imager to evaluate the tissues supplied by the blood vessel on which the interventional procedure was done."

Finally, the university wants to explore, and eventually define, the opportunities for interventional MRI.

"The only way interventional MR can (develop) is to compare it head-to-head against interventional radiology, the x-ray way," Higgins said.

Evaluation of some of the latest thrombolytic clot-busting therapies for stroke patients is of particular interest.

"The combination of the two modalities opens up a therapeutic window and allows more patients to be involved in the trials of a new era of therapies," Roberts said.

The problem in the past has been selecting which patients were likely to benefit. According to Roberts, those patients who present to the emergency room more than three hours after the onset of stroke symptoms are currently denied therapy. That may be about to change. Phase I of UCSF's projected plans for the new suite will be correlative studies comparing the quality and diagnostic utility of the very best of MR angiography with x-ray angiography in the same setting, with the same patient.

"We are going to be ideally suited to do the evaluative MR, slide the patient into (x-ray) angiography, do the intervention, and slide back into MR and evaluate the efficacy of the intervention," Roberts said. "MR can provide you with information about the functionality and the viability of the tissue and then you can go ahead and do your interventional procedure in the x-ray environment, aware of the state of the tissue.

Halfway through the interventional procedure, or when it's finished, the patient can be slid back into MR and the immediate outcome checked, giving the doctor an opportunity to do more if necessary, he said.

Although Philips provided the major funding, UCSF expects to acquire additional resources from its own education and research fund and from federal sources such as the NIH.

"We will also attempt to acquire funds from the American Heart Association, because so much of what we're doing is associated with cardiac disease and stroke," Higgins said.

The marriage of vascular x-ray and MRI over the next five years will be closely followed by radiologists and other medical professionals. According to Higgins, cardiology, vascular surgery, neurosurgery, and neurology will all be involved.