Siemens Medical Systems became the first vendor to test demandfor high-field MR mammography with the recent introduction ofa double breast coil. But the coil could be a product in searchof a niche: While radiologists extol the promise of MR
Siemens Medical Systems became the first vendor to test demandfor high-field MR mammography with the recent introduction ofa double breast coil. But the coil could be a product in searchof a niche: While radiologists extol the promise of MR mammography,they say the procedure is not ready for clinical applications.
The advent of MR mammography has been slow, despite the largesize of the potential market (SCAN 2/11/92). Early studies wereconducted in the mid-1980s, but research lagged as cost concernsand technical difficulties dampened enthusiasm. The use of gadoliniumMRI contrast, however, has improved MR mammography's sensitivityto the point where it could become a viable procedure.
Companies besides Siemens that are watching the market closelyinclude Instrumentarium and Philips, which are both developingbreast coils (SCAN 2/26/92), and Advanced NMR, which is workingon a dedicated mammography scanner (see story, page one).
Siemens, of Iselin, NJ, is actively marketing its new coil,which has Food and Drug Administration approval. The coil is availablefor Siemens' 1- and 1.5-tesla Magnetom scanners and is pricedat $20,000.
Siemens does not expect MRI to take the place of conventionalmammography, according to Anne Deery, MRI communications manager.But the company does see several niche applications for the product,most of which take advantage of problems encountered in mammography.
Potential applications for MR mammography include:
The novelty of the technique and its high price relative toconventional mammography could limit the scope of Siemens' marketingefforts, however. Most radiologists believe more research is neededbefore MR mammography can be used in a clinical setting.
"It has tremendous potential, but it's still a researchtool," said Dr. Steven E. Harms, director of magnetic resonanceat Baylor University in Dallas. "I don't think it's readyfor clinical use."
In studies conducted over the past two years, Harms has scanned130 patients using a GE scanner with a Medrad coil. In testingthe technique for sensitivity, his research group has not missedany cancers, and has picked up lesions as small as 3 mm, Harmssaid.
"It's incredibly sensitive," he said.
But MR mammography's high sensitivity presents new problems.The very small lesions are difficult if not impossible to biopsyusing current techniques, according to Harms. And visualizinglesions that can't be diagnosed as either malignant or benigncould create ethical dilemmas for radiologists.
"What if a woman walked in off the street (for a screening)and you found a very small lesion? What are you going to do?"Harms asked. "Are you going to tell her she has an abnormality,but you can't do anything about it? To me, that's a disserviceto the woman."
A biopsy accessory needs to be developed for MR mammographythat can locate very small lesions and accurately diagnose them,Harms said.
Dr. Daniel B. Kopans, director of the breast imaging centerat Massachusetts General Hospital, also believes MR mammographyneeds more study. But the technique's high sensitivity is nota major problem, in his view.
"To say we're not going to use (MR mammography) becausewe find cancers too early is not the answer," he said. "There'sa direct relationship between the size of the tumor and the prognosis.And I suspect that's going to hold true for smaller and smallerlesions."
Researchers in Germany seem to have overcome many of the difficultiesfacing MR mammography. Dr. Werner Kaiser of University Hospitalin Bonn has conducted pioneering research in the field, and hasdeveloped procedures to differentiate between malignant and benignlesions and to locate tumors for biopsy.
Kaiser believes that widespread clinical use of MR mammographywill occur sooner in Germany than in the U.S. because researchersin that country are more familiar with the techniques necessaryto obtain optimal performance. But MR mammography is a modalitywhose time will come in the U.S.
"I think and I hope that in the next few years MR mammographyprocedures will stay in the hands of research groups," Kaisersaid. "But I feel that due to the exciting results of MRexaminations, this procedure will start sooner than anticipated(in clinical settings)."
One possible niche for MR mammography is in follow-up screeningof women who have had suspicious mammograms, Kaiser said. MR mammographycould deliver cost savings if it proves useful in differentiatingmalignant from benign lesions, making biopsy unnecessary.
Siemens hopes that, as more breast coils find their way intothe hands of radiologists, many of the questions about MR mammographywill be resolved. The coils are being used in research at fivehospitals, which should help generate the data necessary to buildsupport for clinical applications of MR mammography, Deery said.
"For the general population, it probably will not be aneconomical screening device yet," she said. "But atthis point, if you're just a normal MR site, you can add thisto your palate of things you can do."