Low-Dose, Contrast-Enhanced Mammography Compared to Contrast-Enhanced Breast MRI: A Feasibility Study

Abstract

Contrast-enhanced MRI (CE-MRI) is the most sensitive technique for breast cancer detection. Contrast-enhanced mammography (CEM) is emerging as a possible alternative to CE-MRI.

Purpose: To evaluate the diagnostic performance of a low radiation dose contrast-enhanced mammography (L-CEM) in women with suspicious findings on conventional imaging compared to CE-MRI of the breast.

Study type: Prospective, single center.

Population: Women with suspicious findings on mammography, tomosynthesis, or ultrasound, and no contraindications for L-CEM or CE-MRI. Eighty women were included.

Field strength/sequence: 1.5 and 3T CE-MRI, standard protocol for breast, with dedicated coils, according to international guidelines. L-CEM was performed using a dedicated prototype.

Assessment: Three, off-site, blinded readers evaluated the images according to the BI-RADS lexicon in a randomized order, each in two separate reading sessions. Histology served as a gold standard.

Statistical test: Lesion detection rate, sensitivity, specificity, and negative and positive predictive values (NPV, PPV) were calculated and compared with multivariate statistics.

Results: Included were 80 women (mean age, 54.3 years ±11.2 standard deviation) with 93 lesions (32 benign, 61 malignant). The detection rate was significantly higher with CE-MRI (92.5-94.6%; L-CEM 79.6-91.4%, P = 0.014). Sensitivity (L-CEM 65.6-90.2%; CE-MRI 83.6-93.4%, P = 0.086) and NPV (L-CEM 59.6-71.4%; CE-MRI 63.0-76.5%, P = 0.780) did not differ between the modalities. Specificity (L-CEM 46.9-96.9%; CE-MRI 37.5-53.1%, P = 0.001) and PPV (L-CEM 76.4-97.6%; CE-MRI 73.3-77.3%, P = 0.007) were significantly higher with L-CEM. Variations between readers were significant for sensitivity and NPV. The accuracy of L-CEM was as good as CE-MRI (75.3-76.3% vs. 72.0-75.3%, P = 0.514).

Data conclusion: L-CEM showed a high sensitivity and accuracy in women with suspicious findings on conventional imaging. Compared to CE-MRI, L-CEM has the potential to increase specificity and PPV. L-CEM might help to reduce false-positive biopsies while obtaining sensitivity comparable to that of CE-MRI LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 2 J. Magn. Reson. Imaging 2020;52:589-595.

Keywords: breast cancer; contrast-enhanced MRI; contrast-enhanced mammography; radiation dose.

Figure 1

Flow chart with the patients and lesions included in the study. L‐CEM: low‐dose, contrast‐enhanced mammography; CE‐MRI: contrast‐enhanced magnetic resonance imaging.

Figure 2

Low‐dose contrast‐enhanced mammography (L‐CEM, a) and contrast‐enhanced MRI of the breast (second subtracted image, b and c) in a 69‐year‐old woman. Histology revealed an invasive ductal carcinoma in the right breast (arrow in a and c). The lesion shows heterogeneous enhancement and irregular margins in both L‐CEM and MRI and was considered suspicious. A second enhancing lesion with indistinct margins was clearly visible on MRI (arrowhead in b) and considered suspicious as well. In contrast, the same lesions shows only a minimal, nonsuspicious enhancement on L‐CEM (arrowhead in a). Histology showed a benign lesion (papilloma without atypia).

Figure 3

Mean average glandular dose (AGD) and standard deviation calculated per view for increasing breast thickness intervals. As expected, AGD increased with increased breast thickness. Despite this, the low‐dose, contrast‐enhanced mammography system used was able to keep the AGD below 2.49 mGy.