Refinements Made to Near-Infrared Spectroscopy (NIRS) during Clinical MRI

Dartmouth engineers and radiologists are developing new approaches for an emerging technique in diagnostic imaging for breast cancer-MRI with near-infrared spectroscopy (NIRS) as reported in the journal Academic Radiology, February 2014.

Combined MRI/NIRS may benefit women whose mammograms showed an abnormality and require further testing to rule out cancer. The test would be conducted before an invasive biopsy to look for tumors. For the new method to work successfully in routine patient care, MRI/NIRS must adapt to an individual's body size as well as accommodate a range of cup sizes. The equipment must also mobilize and maintain contact with the breast.

An MRI/NIRS may offer specific advantages to women with dense breasts, who are more likely to develop and die from breast cancer. A dense breast is harder for a radiologist to "see through" when using traditional imaging equipment, which lacks the sensitivity to penetrate the dense tissue. Standard breast screening is effective 77-97 percent of the time in a normal breast, but precision falls to 63-89 percent when a breast is dense .

Prior approaches for MRI/NIRS used parallel plates and relied on custom breast molds for each patient. Biomedical engineers from Thayer School of Engineering at Dartmouth developed a new, more flexible, convenient, and comfortable approach. They designed a set of eight light transmitting cables that can be adjusted to surround the breast with light tension. A woman lies on her stomach and the breast hangs pendant through the holes of the MRI/NIRS breast coil. The procedure is nearly identical to clinical MRI.

Engineering research
associate, Michael
Mastanduno

Eight women participated in a trial of the new design. "We found that the new interface allowed us to target lesions more effectively than ever before," said Michael Mastanduno, researcher at Thayer School. "Set up time was faster and images were of higher quality."

The Dartmouth MRI/NIRS offers increased coverage of the chest, giving providers improved visibility for "hard to see" areas, such as the outside area of the breast near the armpit.

"This work is a huge improvement on previous designs of MRI/NIRS systems. All breast sizes and lesion locations can now be effectively imaged. Though there is more work to be done, this technology is promising for improving MRI's ability to distinguish cancer from benign abnormalities," said Mastanduno.

As a next step, Dartmouth researchers will test MRI/NIRS in women with suspicious lesions.

The study was supported by NIH grant RO1 CA069544. Additional authors include: Fadi El-Ghussein, BS, Shudong Jiang, PhD, Roberta DiFlorio-Alexander, MD, Xu Junqing, MD, Yin Hong, MD, Brian W. Pogue, PhD, Keith D. Paulsen, PhD.