- Contrast-enhanced mammography (CEM) is an emerging modality that produces two sets of images, analogous to a combination of conventional mammography and breast MRI
- Recently, the largest systematic review and meta-analysis of CEM to date (10,605 patients from 60 studies) showed CEM has high diagnostic performance in breast cancer detection, with an area under the receiver operating characteristic curve of 0.94
- However, there are limited data about the utility of CEM for breast cancer screening
- In an accompanying editorial, a Massachusetts General Hospital radiologist describes ongoing multicenter trials that should help define the role of CEM in comparison to digital breast tomosynthesis, digital two-dimensional mammography and ultrasound
In Radiology, Italian researchers recently published a comprehensive systematic review and meta-analysis of the diagnostic performance of contrast-enhanced mammography (CEM), an emerging modality for breast imaging.
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An accompanying editorial by Manisha Bahl, MD, MPH, a radiologist in the Breast Imaging Division of the Department of Radiology at Massachusetts General Hospital, comments on how the meta-analysis contributes to the existing literature on CEM. Dr. Bahl also gives insight into the current and potential future clinical utility of CEM.
Background on CEM
CEM is a dual-energy technique that acquires images after intravenous administration of iodinated contrast material:
- Low-energy images that give morphologic and anatomic information, similar in appearance to conventional full-field digital mammograms
- Recombined images (based on both low- and high-energy images) that show areas of contrast material uptake, similar in appearance to breast MRI scans, and providing vascular physiologic information
CEM thus functions at the level of MRI without the challenges of limited access and high cost.
Highlights of the Meta-analysis
The review, the largest to date, included 10,605 patients from 60 studies that had a wide range of study designs, interpretation approaches and clinical settings. The main finding was that CEM performed well in detecting breast cancer, with an overall area under the receiver operating curve of 0.94.
The sensitivity and specificity of CEM were higher when both the recombined images and the low-energy images were interpreted rather than only the recombined images.
On the basis of their results, the researchers suggest CEM might be preferable to MRI for three indications:
- Assessment of suspicious findings detected with conventional mammography
- Supplemental screening in women with dense breast tissue
- Annual screening in women with a history of thoracic radiation therapy (this population is at higher risk of ductal carcinoma in situ, which usually manifests as calcifications and thus could be missed with MRI)
Dr. Bahl comments that the patients who could benefit most from CEM are those who qualify for supplemental screening with MRI but are unable to undergo MRI due to allergies to gadolinium-based contrast material, pacemakers, severe claustrophobia or body habitus. However, to date, CEM is approved only as a diagnostic examination, not for breast screening (and even for diagnosis, reimbursement is low compared with MRI).
The European Commission Initiative on Breast Cancer's Guidelines Development Group recently recommended using CEM instead of MRI for surgical planning in women with biopsy-proven cancer, but the organization called it a conditional recommendation because of low-level evidence.
Multicenter Studies Underway
Only two of the publications included in the meta-analysis (3%) were multicenter studies, and data were limited about using CEM for screening. Dr. Bahl advises clinicians to watch for results from two large multicenter studies:
- The Contrast Enhanced Mammography Imaging Screening Trial (CMIST), sponsored by the American College of Radiology, is comparing the screening performance of CEM to that of digital breast tomosynthesis (DBT) and ultrasound in U.S. women with dense breast tissue who are at average to intermediate breast cancer risk
- Rapid Access to Contrast-Enhanced spectral mammogRaphy (RACER), a four-center randomized controlled trial, includes Dutch women recalled from screening mammography because of indeterminate findings. The objective is to determine whether primary use of CEM in this population is more accurate and cost-effective than DBT, digital two-dimensional mammography or ultrasound
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