Tomosynthesis and Contrast-Enhanced Mammography Improve Cancer Detection

In recent years, a range of advancements in digital mammography have helped to greatly improve breast cancer detection. Indeed, in many countries, these developments are changing the way radiologists work. Key to this is an improved morphological and functional assessment of breast tissue. This was recently illustrated in discussions with experts in the field at the Breast Care Day, which was co-organized by Siemens Healthineers and Bayer, during the European Congress of Radiology (ECR) in Vienna.

It should be noted that the technical parameters of image acquisition already play a role in the efficiency of tomosynthesis. During a procedure, an X-ray tube goes around the breast in order to obtain image projections from different perspectives for 3D reconstruction. According to radiologist Paul Fisher and medical physicist Wei Zhao, both from Stony Brook University, New York, if an X-ray source has a larger angular range, image quality appears to be higher than in the case of a smaller angular range. This is explained by the fact that, in the case of a wider angle, the inside of the breast can be viewed more easily and thus fewer data artifacts are necessary for image reconstruction.

Also important for the reading process is easy orientation in the tomosynthetic image material. Currently, conventional full-field digital mammography (FFDM) is therefore often performed in addition to tomosynthesis, to expedite image interpretation and facilitate comparisons with prior images, using the overview image in 2D.

Now, however, an alternative to FFDM is a “synthetic” mammogram reconstructed from tomosynthesis data, explained Paola Clauser from the Medical University of Vienna, Austria. “Synthetic mammography provides a reliable 2D image – without the need for a double radiation exposure,” said Clauser. Other studies have supported the diagnostic value of this approach. Conventional mammography remains in its own right superior to synthetic images, yet in combination with tomosynthesis, they represent a trendsetting approach.

Yet another new paradigm is emerging: the use of mammography for functional imaging. This is based on the fact that, in order to grow, breast tumors form new blood vessels.[3] This neoangiogenesis can be made visible at a high resolution if a contrast agent containing iodine is given during the examination, explained Luis Pina from the University Clinic of Navarra, Spain. The method, known as contrast-enhanced dual energy mammography, works with X-rays of different energy levels, which are attenuated to different extents by breast tissue and the iodine contrast agent. In addition to a low energy mammographic image, that can be compared to a conventional mammogram, a high energy image is acquired leading to a calculated subtraction image, which sets apart and unmasks heavily perfused tumor tissue from its surrounding area.[4]

“The approach is a problem-solving technique,” stressed Pina. In cases that cannot be sufficiently clarified through mammography or tomosynthesis, the contrast agent method often provides further help, for example, in the case of particularly dense breast tissue, preoperative staging, or follow-up of scars. In many constellations, the method offers an alternative to magnetic resonance imaging, which – if applicable – takes longer and can be quite costly.
In addition, contrast enhancement is also possible in tomosynthesis, as Fisher added. According to initial study results with a prototype system, contrast-enhanced tomosynthesis enabled a particularly good assessment of the diagnostically important margin areas of lesions suspected of being cancerous.⁶ Moreover – as in the case of examinations without a contrast agent – synthetic 2D overview images could be generated.
The latest diagnostic systems, such as MAMMOMAT Revelation, actually integrate all of these methods and can be used for traditional as well as contrast-enhanced mammographies, tomosynthesis, synthetic image reconstructions and image-guided biopsies. These advanced devices allow radiologists to choose the best approach in each case from a growing repertoire of methods, depending on the clinical constellation.