Stereoscopic 3D mammography enhances lesion detection
“The results suggest that stereo mammography could bring a substantial improvement over standard mammography in the accuracy of lesion detection and, with that, substantial gains in the cost-effectiveness of breast cancer screening,” said David J. Getty, PhD, who shared the trial outcomes at IWDM.
Stereoscopic 3D FFDM utilizes a combination of image acquisition, software and display technology to achieve volumetric 3D image viewing capabilities for an interpreting physician. Getty, of Cambridge, Mass.-based BBN Technologies, is a developer of the system.
“Stereo mammography exams acquire a pair of images captured with the x-ray tube rotated by 10-degrees between the two acquisitions while the breast remains uncompressed and unmoved,” Getty said.
The stereo mammograms are viewed on a prototype medical stereo display, the StereoMirror SD2250, developed by Planar Systems and demonstrated in the Fujifilm Medical Systems’ booth at the IWDM conference.
The prototype consists of two 5-megapixel, grayscale monitors, mounted one above the other, with an angular separation of 110 degrees between the faces. The cross-polarized images, displayed on one of the two monitors, are transmitted and reflected onto a coated glass plate that bisects the angle between the two monitor faces.
“The radiologist wears lightweight, passive, cross-polarized glasses such that the left eye sees only the reflected image from the upper monitor, while the right eye sees only the transmitted image from the lower monitor,” Getty said. “The radiologist’s visual system fuses the two images into a single in-depth image of the internal structure of the breast.”
The Emory study enrolled 1,458 women at an elevated risk for breast cancer who agreed to undergo a standard FFDM study on a GE Healthcare Senographe 2000D as well as a stereoscopic FFDM exam utilizing the same modality. Screening exams consisted of cranio-caudal and medio-lateral-oblique views.
The standard and stereo digital mammograms for each patient were interpreted independently by two radiologists, with prior mammograms available for comparison in 99 percent of the cases.
Standard mammography demonstrated a true-lesion detection rate of 61.4 percent, while stereoscopic 3D provided a true-lesion detection rate of 75.7 percent; a 23.7 percent detection rate.
Standard mammography was responsible for 130 of 192 false-positive lesion detections (67.7 percent), while stereoscopic 3D was responsible for 70 (36.5 percent).
“This 46 percent reduction in false-positive reports with stereo mammography is highly statistically significant,” Getty noted.
He believes that the difference can be attributed to the volumetric structure of a lesion being visualized on the prototype.
“We believe the large reduction in false positives is due to the fact that normal tissue or unrelated calcifications at different depths, that would be superimposed in a 2D projection and resemble a focal lesion, are seen in the stereo mammogram as layers or normal tissue or unrelated calcifications lying at different depths through the breast,” Getty said.