Abbreviated breast magnetic resonance imaging is a cost-effective screening tool that should be made available to patients with an average lifetime risk of breast cancer, according to our recent review of protocols.
Abbreviated breast MRI provides high diagnostic accuracy with shorter image acquisition and interpretation time. Many studies have evaluated different abbreviated breast MRI protocols for screening and diagnosis of known lesions. As the technology continues to evolve to overcome some technical challenges, evidence continues to confirm the robust diagnostic accuracy of abbreviated breast MRI overall.
Given its robust accuracy and shorter exam and reading times, abbreviated breast MRI is an attractive, cost-effective option, especially as there is increased scrutiny on rising overall healthcare expenditures and a shift away from a fee-for-service to a value-based healthcare paradigm. However, the cost of abbreviated breast MRI is still being evaluated in multiple studies. As a result, reimbursement for an abbreviated breast MRI exam and how to best implement it in the clinical workflow still need to be resolved. The landmark ECOG-ACRIN 1141 Trial will provide some highly anticipated cost-effectiveness insights that we hope may pave the way for more patients to access abbreviated breast MRI in the future. (1)
Breast MRI is the most sensitive imaging method to detect cancer, outperforming mammography, digital breast tomosynthesis, and ultrasound. (1) Dynamic contrast-enhanced MRI (DCE-MRI) was first recommended for women with a high lifetime risk (greater than 20 percent) of breast cancer, (2), (3), (4)and then later for women with an intermediate lifetime risk (greater than 15 percent). (5)Despite encouraging results among women at an average risk, conventional breast MRI is currently not recommended as a screening method, mostly due to its higher relative costs and lack of widespread availability compared to conventional imaging. (6), (7)
Abbreviated breast MRI includes only the most useful series of images. A groundbreaking study published in 2014 evaluated abbreviated protocols generated from full protocols in 606 examinations of 443 women by comparing diagnostic accuracy, cancer yield, and acquisition time. The protocol involved an unenhanced T1-weighted and first contrast-enhanced T1-weighted sequence, subtraction imaging, and a single maximum intensity projection (MIP) image. All 11 cancers were found with equivalent diagnostic accuracy for the abbreviated and full protocols, and the evaluation of the MIP image alone failed to detect just one cancer. At the same time, the acquisition time for the abbreviated protocol was three minutes compared to 17 minutes for a full diagnostic protocol, and interpretation time was 28 seconds on average, or 2.8 seconds when only the MIP image was evaluated, compared to two to four minutes for screening mammography interpretation. (8)
Since then, many studies investigating different abbreviated breast MRI protocols for the screening and investigation of known lesions have followed. Some studies relied on T(2)-weighted or short inversion time (TI) inversion recovery (STIR) sequences; others relied solely on DCE-MRI. However, they all found similarly strong diagnostic accuracy for abbreviated breast MRI compared to a full protocol. (1) Further, a recent study comparing the full diagnostic protocol to an abbreviated protocol in 1,052 cases found that final BI-RADS assessments were revised for only 3.4 percent with the full protocol. (9)
Overcoming Challenges with Abbreviated MRI
One of the limitations of abbreviated breast MRI is that the kinetic information of breast tumors is not as robust given the shortened acquisition time. Several studies have investigated whether imaging acceleration techniques can overcome this drawback. Techniques explored have included time-resolved angiography with stochastic trajectory (TWIST), high sensitivity-encoding (SENSE) acceleration factor, a volumetric imaging technique with a 0.8 millimeter (mm) isotropic resolution and 10-s/volume rate for breast cancer using spatial compressed sensing and parallel imaging, and time-resolved imaging of contrast kinetics (TRICKS) acquisitions. Overall, these studies found that the necessary kinetic information for an accurate breast cancer diagnosis can be provided, even with abbreviated breast MRI. (1)
Recently, there has been some concern that the gadolinium-based contrast agent used with DCE-MRI can cause MRI signal changes in the deep nuclei of the brain. (1) The clinical significance of brain retention of this contrast agent is unknown, and there is no scientific evidence of adverse effects. However, in light of the controversy, the use of gadolinium-based contrast agents is only recommended when essential diagnostic information cannot be obtained with unenhanced scans. (10), (11)
Diffusion-weighted imaging (DWI) has emerged as the most valuable and robust technique so far. It delivers a sensitivity of up to 96 percent for breast cancer detection and a specificity of up to 100 percent for breast tumor characterization. In all but one of the studies that we reviewed, we found that the sensitivity of abbreviated unenhanced MRI was equal to or outperformed mammography. (1)One caveat to consider is that the sensitivity of DWI is limited in lesions ≤ 12 mm or presenting as diffuse nonmass enhancement. (12)Research to improve the spatial resolution is ongoing. We anticipate that continuing advances will address this limitation and that we will see abbreviated breast MRI protocols with combined DCE-MRI and DWI in the future.
Value-Based Cancer Care
Policy makers have recently focused on curbing the use of advanced imaging exams, especially computed tomography and MRI, while promoting the quality and appropriateness of imaging. A variety of new clinical decision support tools have been introduced, many of which limit the use of advanced imaging tools. A correct diagnosis is the first outcome that matters to patients, and new metrics have been developed to measure a radiologist’s impact in terms of contributions to reducing costs while improving outcomes. (13)
Most studies have found that an abbreviated breast MRI exam provides a similar diagnostic accuracy as a full breast MRI exam. However, the cost of an abbreviated MRI is still being evaluated. Multiple studies are underway to determine whether abbreviated MRI exams are cost-effective for initial diagnosis.
MSK is one of 68 study sites participating in the ECOG-ACRIN 1141 Trial, which will address the cost issue. The trial is comparing abbreviated breast MRI and digital breast tomosynthesis for the detection of breast cancer in average-risk women with dense breasts.
One of the secondary outcome measures is a comparative cost evaluation of both exams. The results for this trial are highly anticipated: Recruiting is complete, and the primary study completion date is December 31, 2018. Until then, a reasonable cost estimate for abbreviated breast MRI would be in line with low-cost mammography, digital breast tomosynthesis, and screening breast ultrasound exams.
At MSK, we strive to optimize patient outcomes with the latest, most accurate, and cost-effective imaging techniques. We offer abbreviated breast MRI on trial, as well as contrast-enhanced digital mammography, fluorescence imaging, and PET and MRI technologies, to assist precise investigations and biopsies and, in some cases, to guide the delivery of treatment. As members of the breast cancer team, we collaborate with multidisciplinary experts to deliver individualized diagnostic and treatment plans for each patient.
Acknowledgement: This research was sponsored by the National Institutes of Health, National Cancer Institute, and Breast Cancer Research Foundation.