Combined MRI-Optics Technique Provides Breast Cancer Diagnosis

The new technique utilizes MRI to produce an image of the breast, providing information on its structure, including shape and composition. The near-infrared light technique provides data on how the tissue is functioning, such as, whether a region contains a large amount of blood and is rapidly consuming oxygen as early tumors typically do. The researchers, from Dartmouth College Medical School (Hanover, NH, USA), are hoping this dual-procedure approach will be a vital application to learning which tissues are malignant before performing a biopsy. Their pilot study, demonstrating the feasibility of the concept, was published in the April 15, 2007, issue of the journal Optics Letters.

The pilot study involved a 29-year-old woman with a ductal carcinoma, a very common breast tumor, in her left breast. A contrast-enhanced MRI procedure was performed, where MRI was performed before and after the contrasting agent gadolinium was injected. The area enhanced by the contrasting agent was targeted for the optical technique, known as near-infrared spectroscopy (NIRS). The study's findings showed the area's hemoglobin level was high, oxygen saturation was low, and water content was high, all indicators of cancerous tissue.

Recent developments in medical imaging systems have focused on increasing the detail of anatomic images, but there has also been a growing interest in devices that provide information on tissue function. One of the difficulties with functional imaging has been that most of these devices have low spatial resolution. The structural information from the MR image helps guide the NIRS technique to the regions of interest so that the two can together create high-resolution, functional images of breast cancer.

Mammograms are much less costly than MRI, but because they compress the breast to show all of the information in one view, they are less effective of a tool, particularly when the breast is dense. MRI provides multiple slices of high-resolution images of breast tissue, creating a three-dimensional image. Unlike mammography, the NIRS technique does not generate images directly from the data acquired by the machine. It records the spectrum of near-infrared light that is absorbed or scattered (bounced around) in the tissue.

If larger studies prove to be successful, and the U.S. Food and Drug Administration (FDA) considers the procedure valuable enough for insurance reimbursement, Dr. Paulsen reported that this new method could become more widely available within the next five years.


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Dartmouth College Medical School