Cone-beam breast computed tomography produces exceptional tissue contrast and can reduce examination time with comparable radiation dose compared with conventional two-dimensional mammography, according to an article in the December issue of the American Journal of Roentgenology.

Cone-beam technique employs a large area x-ray beam with a flat panel x-ray detector to scan and generate three-dimensional images of the breast. The scanner is placed below a table on which the patient lies prone with the breast protruding through an opening. Only the breast is exposed to radiation, improving image quality and sparing the rest of the body from unnecessary radiation. The scan can be completed in less than one minute with a single complete rotation of the x-ray tube-detector gantry around the breast. Unlike conventional tomography, the patient is not moved through the gantry during scanning.

Researchers at M.D. Anderson Cancer Center, Houston, TX, used cone-beam computed tomography on 12 mastectomy specimens. Structured noise was minimal because of the absence of overlapping tissue; anatomy was well resolved on all images as skin, adipose, and glandular regions, and microcalcifications within cancers were clearly shown.

In addition, the researchers discovered that detection of cancers based on morphologic assessment of tissue structures could potentially be improved compared with mammography because of the lack of overlapping glandular tissue.
"Despite the advantage of excellent spatial resolution, conventional mammography is unable to diagnose all cancers, especially early cancers in dense breasts, and cancers in high risk women such as genetic carriers," said Wei Tse Yang, MD, lead author.

"In addition to overcoming the problem of overlapping breast tissue, cone-beam breast CT has the ability to provide true three-dimensional images of the breast that may help depict the three-dimensional morphology and distribution of lesions, and that may provide incremental benefit in the differentiation of abnormalities from background breast tissue. In addition, the multiplanar high-resolution surveys it provides are at a radiation dose comparable to routine mammography," said Yang.

Besides those benefits of cone-beam breast computed tomography, the researchers pointed out others, as well. "Scanning using this method takes less than one minute. This compares with 40 minutes for breast magnetic resonance imaging (MRI), and 10 minutes for mammography. It also eliminates the discomfort associated with compression during mammography and the problem of claustrophobia during MRI," said Yang.