Contrast-enhanced digital mammography along with Ultrasound or MRI Predicts True Positive Results: AJR

CEDM is one of the relatively novel imaging modalities and has been shown to outperform standard mammography while performing comparably to contrast-enhanced MRI. It provides low-energy images comparable to mammographic images and post-contrast recombined images to evaluate tumour neovascularity. CEDM allows better evaluation of calcifications by their visualization on low-energy images combined with enhancement criteria on the contrast-enhanced recombined images. Researchers of the Memorial Sloan Kettering Cancer Center, New York, recently conducted a study to compare imaging characteristics of false-positive and true-positive findings on CEDM.

In this retrospective study, the researchers included a total of 157 women who underwent baseline screening CEDM and were assessed with BI-RADS category 0, 3, 4, or 5 and who underwent biopsy with histopathologic diagnosis or had two-year imaging follow-up. They extracted lesion characteristics from CEDM reports. They determined a true-positive finding as a lesion in which biopsy yielded malignancy and a false-positive finding as a lesion in which biopsy yielded benign or benign high-risk pathology, or two-year imaging follow-up was negative.

Key findings of the study were:

• Among 157 patients, the researchers identified 24 had a total of 26 true-positive lesions, and 133 had a total of 147 false-positive lesions.
• Out of 26 true-positive lesions, they observed 1 (4%) exhibited only a mammographic finding on low-iodine images, 13 (50%) had only a contrast finding on iodine images, and 12 (46%) had both a mammographic finding on low-energy images and a contrast finding on iodine images.
• They noted that the true-positive result was more likely for lesions present on both low-energy and iodine images (31%) than on low-energy images only (4%) or iodine images only (12%).
• Among lesions present on both low-energy and iodine images, they found that a true-positive result was more likely when the type of mammographic finding was asymmetry (50%) or calcification (80%) than mass (11%) or distortion (0%).
• They further noted that the true-positive result was more likely among those with, versus without, an ultrasound correlate (36% vs 9%), and also more likely among those with, versus without, an MRI correlate (18% vs 2%).
• They noted that out of 25 false-positive calcifications, 24 had no associated mammographic enhancement. And, out of 5 true-positive calcifications, 4 had mammographic enhancement.

The authors concluded, "A low-energy mammographic finding with associated enhancement, or a finding with sonographic or MRI correlate, predicts a true-positive result. Calcifications with associated enhancement had a high malignancy rate. Nonetheless, half of true-positive lesions enhanced on iodine images without a mammographic finding on low-energy images."

They further added, "These observations inform radiologists' management of abnormalities detected on screening CEDM."

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DOI: https://doi.org/10.2214/AJR.21.26847