CT technique opens door for breast imaging at 25x lower dose

Researchers have developed a CT technique that can produce 3D images of the breast at a radiation dose lower than mammography, according to an article published Oct. 22 in the online Early Edition of the Proceedings of the National Academy of Sciences.

The method allows for CT images with a spatial resolution two to three times higher than present scanners, but with a radiation dose about 25 times lower. "This new technique can open up the doors to the clinical use of computed tomography in the breast diagnosis, which would be a powerful tool to fight even better and earlier against breast cancer,” Maximilian Reiser, MD, of Ludwig Maximilians University (LMU) in Munich, said in a release.

The improved results are possible by combining three factors: high energy x-rays, phase contrast imaging and the use of a mathematical algorithm known as equally sloped tomography (EST). Tissues are more transparent to high energy x-rays, and phase contrast imaging requires less x-rays to obtain the same image contrast, both resulting in lower dose.

EST, developed at the University of California-Los Angeles (UCLA), is used to reconstruct the CT images and requires less radiation to obtain the same image quality. Jianwei (John) Miao, PhD, of UCLA, explained this is possible because the EST algorithm requires fewer slices to obtain a clear 3D image.

Researchers used phase contrast tomography and applied the EST algorithm to 512 breast images. They reported lower doses than mammography, and in a blind evaluation, five radiologists from LMU rated the generated images as having higher sharpness, contrast and overall image quality compared with 3D images of breast tissue obtained with standard imaging methods.

While the technique could make CT scans a complementary diagnostic tool to dual-view mammography, the technology is in the research phase and will not be available to patients for some time. In an email to Health Imaging, Miao explained that the technique requires a high-quality x-ray source that is small enough for common use in breast cancer screening. He said many groups are working on developing such a system, and he thinks it may happen within 10 to 20 years. “Once this hurdle is cleared, our research is poised to make a big impact on society.”