Each year, in the last few days of November, the world of radiology descends on the city of Chicago for the annual meeting of RSNA, the Radiological Society of North America. There are 60,000 delegates to the meeting, a third of them radiologists, and many who travel from outside North America to find out what is happening in their field. Although almost a thousand companies exhibit their imaging systems, while using the opportunity to launch new products, the major focus of RSNA is on clinical research findings. It’s where the radiological community gathers to learn about the latest developments.
At a special session held earlier this week, researchers reported on digital breast tomosynthesis (DBT) and concluded that it showed promise in detecting and characterizing masses, especially among women who have dense breast tissue. According to Dr Mark Helvie of the University of Michigan, “DBT does allow us to remove overlapping tissue artefacts, especially in dense breast tissue, [and] offers better screening sensitivity than full-field digital mammography alone. But there are trade-offs in terms of dose and performance. We don’t get functional information [from the DBT images].”
Functional information comes from nuclear medicine (or radionuclide) images, which includes positron emission mammography (PEM), breast-specific gamma imaging (BSGI), and molecular breast imaging (MBI). The common thread running through these techniques is an injection, into the woman’s bloodstream, of a radiopharmaceutical agent with the image captured by specialized detectors. The nuclear medicine imaging modalities were also the focus of a special course at RSNA this week.
A group from the Mayo Clinic in Minnesota presented their findings on using MBI to screen for cancer in patients with dense breasts. They found a significant increase in sensitivity compared with standard mammography even when the dose of the radiopharmaceutical agent was reduced substantially. Of course in a screening environment, there is the added cost of the agent, plus the time to gather the images, that have to be taken into account.
Dr Wendie Berg from Pittsburgh, one of the leaders in nuclear medicine imaging of the breast, concluded, “There is evidence of clinical benefit. I can’t emphasize enough how important it is to correlate nuclear medicine results with a patient’s current mammography, ultrasound, biopsy, and pathology history.”