Researchers at Johns Hopkins have for the first time used a chemical marker detected by proton magnetic resonance spectroscopic imaging (MRSI) to successfully diagnose breast cancer. The diagnostic technique produces pictures of choline within breast tumors.

In the study, researchers from the Russell H. Morgan Department of Radiology and Radiological Science at Hopkins demonstrated that choline signals analyzed by MRI were significantly elevated in malignant tumors in 15 of 18 patients studied. Three of the cases could not be included because of technical failures such as patient movement or computer failure during the scanning procedure.

The results are published in the December-January issue of the Journal of Magnetic Resonance Imaging.

Scientists have long known that cancers contain elevated levels of choline, a product of membrane synthesis, but the Hopkins study is believed to be the first to demonstrate its value in accurately identifying breast tumors.

MRSI of the breast does not appear likely to be cost-effective as a routine screening tool for breast cancer, but may prove to be a viable, noninvasive alternative to biopsy in cases with positive mammography or clinical breast exam results, says Michael A. Jacobs, Ph.D., the lead researcher for the Hopkins study. "What MRSI does provide is information about the molecular environment of breast tumors, which also may be useful in designing therapeutic interventions for patients."

Proton magnetic resonance imaging uses the water content in tissue to produce images by measuring signals emitted after subjecting the tissue to high magnetic fields, but provides no information on the chemical or molecular aspects of the tissue being imaged. Combining proton MRI with spectroscopy allows the scientists to differentiate intracellular components of the cell and signals emitted by certain biochemicals, such as choline.

In the study, 15 patients who had been referred for MRI evaluation after previous examination had revealed breast tumors underwent regular breast MRI to identify the lesion. These studies were followed by MRSI scanning to determine if choline signals in the tumors could be adequately imaged using spectroscopy. Biopsies performed after the imaging revealed that eight of the tumors were malignant carcinomas and seven were benign. MRSI showed elevated choline levels in all eight of the malignant tumors.

"These data are proof of principle, and strongly suggest that MRSI can serve as an important adjunct to the routine MRI scan that may aid physicians in making a diagnosis of breast cancer," says Jacobs. "We can envision a time when this procedure may even replace the need for biopsy in some cases and provide the basis to follow treatment strategies in certain cases of breast cancer. However, more research is needed to fully understand the potential impact of these findings."