BOSTON (CBS) – Imagine a breast imaging test that could tell doctors which lumps are cancerous and which are benign. Knowing that could save millions of women from getting unnecessary and, sometimes painful, tests.

Local doctors say they’ve developed a test that, even in its early stages, seems to show great promise.

3-D digital mammography has been used for years to find suspicious breast lesions. Now doctors at Mass General have found combining that screening with a new optical imaging technique which measures hemoglobin and oxygen levels in breast tissue can help them better identify which lesions could be cancerous. That’s because they discovered that breast tumors have higher hemoglobin levels.

“Our goal is to use optical imaging to improve our ability to detect breast cancer and to differentiate breast cancer from normal and benign cysts,” explained Dr. Daniel Kopans, the director of the Breast Imaging Center at Mass. General Hospital.

Experts say a lot more studies need to be done, but they hope that combining these two non-invasive techniques will help spare women from being called back for unnecessary follow-up procedures and biopsies.

“Further down the line we hope to fuse these techniques to find cancers that we may not have suspected,” said Dr. Kopans. “It has a lot of potential. We need to work harder.”

Doctors say they are also using optical imaging techniques to look for other tumors, including colon cancer.