Optical Mammo Promises Specific Images, More Comfort

Optical mammography isn’t new technology, but researchers at Tufts University School of Engineering have given it an upgrade. Now, the technique allows radiologists to obtain mammography images without radiation and with greater patient comfort.

With the support of a 3.5 million grant from the National Institutes of Health, investigators created a stand-alone, portable scanner that uses near-infrared light - rather than ionizing radiation - to scan the breast. Specialized software, using an algorithm based on optical information, translates the intensity of the transmitted light into breast images.

Patients are currently being recruited for a clinical study that will look at the scanner’s efficacy in differentiating between healthy and cancerous tissue, as well as benign lesions.

The goal, according to lead investigator and Tufts biomedical engineering professor Sergio Fantini, PhD, is to potentially provide more specific breast screenings that prompt a lower number of false positives. That change could ultimately result in fewer follow-up appointments and biopsies than traditional mammography.

“For breast screening, X-ray mammography is the gold standard, and conceptually, this is really the same thing,” Fantini said. “But the information content that we obtain with optical mammography is more related to the hemoglobin in blood and what it tells us about blood flow and oxygenation.”

In addition, optical mammography can also give you information about the amount of water and fat in breast tissue, he said. You can discern between water and fats, as well as high and low oxygen levels by how much light the tissues absorb - all details that help you diagnose cancers. The clinical study is designed to determine if Tufts’ optical mammography scanner can readily differentiate between malignant and benign lesions.

According to Lee Kijoon, PhD, assistant bioengineering professor at Nanyang Technological University in Singapore, “Optical imaging in the breast will completely change our method of breast cancer screening and therapy monitoring in the future,” he wrote in a 2011 study published in the World Journal of Clinical Oncology. “X-ray mammography will remain as a method of choice for some time, but the advantages of optical mammography will eventually be recognized in the clinical community.”

To reach that level of acceptance, he added, the technology must improve its spatial resolution and further increase tumor specificity.

Although other research groups are working on optical mammography, the tool developed at Tufts has several unique features. First, according to Fantini, the team’s intent is to develop a stand-alone tool that isn’t combined with ultrasound, X-ray, or other imaging method, and that doesn’t use a contrast agent. The scanner is also able to achieve full spectral information in every image pixel.

Optical mammograms also offer additional comfort for the patient, Fantini said. Rather that compressing breast tissue as thin as possible to ensure soft tissues absorb enough radiation to produce quality images, this device lightly holds the breast between two glass panels while infrared light enables the scan.

Previous attempts at optical imaging and mammography in the 1970s and 1980s enjoyed little progress because no clinical studies existed to prove their efficacy, Fantini said. However, with this clinical study and technological improvements, optical mammography could become a widely-used technique for breast imaging. Kijoon agreed.

“Optical imaging a promising non-invasive, deep tissue functional imaging modality that is especially suitable for breast cancer diagnosis and treatment monitoring,” Kijoon wrote. “It will find increasing applications in clinics.”

Caption: Shown is an optical mammography image of hemoglobin oxygenation of a duct carcinoma in situ (DCIS). The boxed area corresponds to the cancer location and indicates lower values of hemoglobin oxygenation. For cancerous tissue that is associated with abnormal hemoglobin concentration and oxygenation, optical mammography can be used to help diagnose breast cancer and also indicate how well a patient responds to breast cancer chemotherapy. (Credit: Sergio Fantini, PhD, professor of biomedical engineering at Tufts University)