BBN Technologies

Limitations of Standard Mammography
The current standard method to screen for breast cancer is x-ray mammography. In a standard mammographic screening exam, radiologists view the breast in the form of two orthogonal 2D images, which severely limits their ability to derive information about the three-dimensional layout of the breast tissue. Specific limitations in lesion detection with standard mammography include:

• A true lesion often remains undetected when masked in the 2D images by overlying or underlying normal tissue, leading to false negative examinations.
• Overlapping of normal tissue at different depths within the breast, which in the 2D projected image may mimic a true focal lesion, lead to false positive detections.
• Information regarding the volumetric structure of the breast that can be derived from the pair of 2D images is very limited and often omits information that can be important in detecting suspicious lesions.

Earlier and More Accurate Detection with Stereoscopic Digital Mammography
With BBN’s patented Stereoscopic Digital Radiography system, the radiologist sees the breast in stereo providing a direct, intuitive, in-depth view of the internal structure of the breast. The stereoscopic display workstation developed by BBN consists of a high-resolution grayscale stereo display developed by Planar Systems Inc in collaboration with BBN, and a BBN-developed software application that permits the radiologist to control many aspects of the displayed stereo image.

By providing an in-depth view of the breast, stereo mammography substantially reduces the limitations of standard mammography:

• Masking of subtle lesions is reduced by their separation in depth from surrounding normal tissue.
• False positive detections are reduced because layers of normal tissue are directly seen to lie at different depths in the breast and don’t superimpose to resemble a lesion.
• The internal structure of the breast is directly appreciated in depth.

Results from an Ongoing Clinical Trial
With support from the U.S. Army Medical Research and Materiel Command, we are now conducting a clinical trial of stereoscopic digital mammography compared to standard (non-stereo) digital mammography for more accurate detection of lesions and reduced rate of recall of patients for unnecessary further examinations. With over 900 patients enrolled as of March, 2007, the trial indicates dramatic diagnostic improvements using stereo mammography in both the rate of missed true lesions and the rate of false positive detections.

Although the stereoscopic digital imaging technique has so far been tested only in mammography, BBN’s patent covers the technique itself and may be applied to other medical imaging applications.