Heacock: That was the purpose of this review article on abbreviated breast MRI – to summarize the different protocols that have been tested, including the plusses and the minuses of the sequences that can be added.
A normal breast MRI acquires several sequences before contrast, then additional specific images after contrast injection. These post-contrast sequences are typically acquired 1-to-3 minutes apart so that we can see how the injected gadolinium contrast washes in and out of the breast over time. In abbreviated MRI, researchers have shown that the first set of images taken after contrast are the ones most likely to show cancers. As a result, in an abbreviated MRI, we don’t acquire additional delayed post-contrast sequences. But, as the literature shows, radiologists who read these exams have the same sensitivity for breast cancer detection while shortening the exam. That means you image the patient in a shorter amount of time, and, for the radiologist, there are fewer sequences to review. That decreases radiologist interpretation time.
Diagnostic Imaging: What are the limitations that exist, and what impacts do they have on abbreviated MRI?
Heacock: Those are all questions we’re currently trying to sort out in the literature. Until now, most abbreviated MRI studies have been retrospective. A radiologist reviews selected abbreviated sequences from a full exam and decides if they can find a breast cancer in these images. There have been fewer prospective trials where the patient is specifically scanned with an abbreviated MRI protocol.
Recently there was a very big multi-center prospective study published which was very exciting. It’s the Eastern Cooperative Oncology Group-American College of Radiology Imaging Network (ECOG-ACRIN) 1141 study. The initial results came out in February of this year. It was a large study in both community and academic practices in which average risk women with dense breasts were prospectively screened abbreviated breast MRI. It was compared to digital breast tomosynthesis for breast cancer detection, and the results were that abbreviated MRI had better cancer detection rates than digital breast tomosynthesis – the current standard of care for average risk screening.
So, we know that for screening, abbreviated MRI appears very useful. What is not yet known is whether it’s good for other types of breast MRI indications, as well. For example, we use breast MRI for patients with a known breast cancer to see if there are any additional concerning findings in either breast. We also use it after a woman has been diagnosed with cancer and has undergone chemotherapy to assess the treatment response. And, we also use it for problem solving when a patient has a specific concern that needs further evaluation. We need to know if these women can have an abbreviated breast MRI or a longer breast MRI.
The literature is still ongoing on whether abbreviated MRI would be as useful for evaluating the extent of disease in a known breast cancer. There have been early results, to date, that have been promising the for evaluation of known cancers. I would like to see more studies looking at this topic. We know from the evidence to date that after neoadjuvant chemotherapy, the delayed post-contrast images that we don’t use in abbreviated MRI – but use in a full-breast MRI – are useful in evaluating treatment response. These patients likely need a longer examination.