Detection of Contralateral Breast Cancer Using Diffusion-Weighted Magnetic Resonance Imaging in Women with Newly Diagnosed Breast Cancer: Comparison with Combined Mammography and Whole-Breast Ultrasound

Abstract

Objective: To compare the screening performance of diffusion-weighted (DW) MRI and combined mammography and ultrasound (US) in detecting clinically occult contralateral breast cancer in women with newly diagnosed breast cancer.

Materials and methods: Between January 2017 and July 2018, 1148 women (mean age ± standard deviation, 53.2 ± 10.8 years) with unilateral breast cancer and no clinical abnormalities in the contralateral breast underwent 3T MRI, digital mammography, and radiologist-performed whole-breast US. In this retrospective study, three radiologists independently and blindly reviewed all DW MR images (b = 1000 s/mm² and apparent diffusion coefficient map) of the contralateral breast and assigned a Breast Imaging Reporting and Data System category. For combined mammography and US evaluation, prospectively assessed results were used. Using histopathology or 1-year follow-up as the reference standard, cancer detection rate and the patient percentage with cancers detected among all women recommended for tissue diagnosis (positive predictive value; PPV₂) were compared.

Results: Of the 30 cases of clinically occult contralateral cancers (13 invasive and 17 ductal carcinoma in situ [DCIS]), DW MRI detected 23 (76.7%) cases (11 invasive and 12 DCIS), whereas combined mammography and US detected 12 (40.0%, five invasive and seven DCIS) cases. All cancers detected by combined mammography and US, except two DCIS cases, were detected by DW MRI. The cancer detection rate of DW MRI (2.0%; 95% confidence interval [CI]: 1.3%, 3.0%) was higher than that of combined mammography and US (1.0%; 95% CI: 0.5%, 1.8%; p = 0.009). DW MRI showed higher PPV₂ (42.1%; 95% CI: 26.3%, 59.2%) than combined mammography and US (18.5%; 95% CI: 9.9%, 30.0%; p = 0.001).

Conclusion: In women with newly diagnosed breast cancer, DW MRI detected significantly more contralateral breast cancers with fewer biopsy recommendations than combined mammography and US.

Trial registration: ClinicalTrials.gov NCT03835897 NCT04619186 NCT03607552.

Keywords: Breast cancer; Diffusion-weighted imaging; Mammography; Screening; Ultrasonography; Ultrasound.

Conflict of interest statement

The authors have no potential conflicts of interest to disclose.

Copyright © 2021 The Korean Society of Radiology.

Figures

Fig. 1. Flow chart of the study population and diagnosis of contralateral breast diseases.

DW = diffusion-weighted, US = ultrasound

Fig. 2. The bar graph shows the number of clinically occult contralateral cancers detected by each imaging modality.

DCIS = ductal carcinoma in situ, DW = diffusion-weighted, MG = mammography, US = ultrasound

Fig. 3. Images of a 45-year-old woman with a 0.7-cm invasive ductal carcinoma in the left breast (patient no. 5 in Table 2).

A. Axial image from DW MRI (b = 1000 sec/mm2) showing an irregular mass (arrow) with high signal intensity in the outer breast. The mass showed a low mean apparent diffusion coefficient value (1.06 × 10−3 mm2/sec) and was assessed as BI-RADS category 4, suspicious on DW MRI. B. Craniocaudal view mammography shows a heterogeneously dense breast with no suspicious findings. The lesion was also negative on US (not shown), and combined mammography and whole-breast US showed that it was BI-RADS category 1, negative. C. Targeted US after MRI shows an irregular hypoechoic mass (arrow) with nonparallel orientation in the corresponding area to DW MRI. US-guided biopsy and surgery revealed a low-grade node-negative invasive ductal carcinoma. BI-RADS = Breast Imaging Reporting and Data System, DW = diffusion-weighted, US = ultrasound

Fig. 4. Images of a 31-year-old woman with a 1.2-cm ductal carcinoma in situ in the right breast (patient no. 26 in Table 2).

A. Axial image from DW MRI (b = 1000 sec/mm2) showing an irregular mass (arrow) with high signal intensity at the glandular-fat junction of the posterior breast. The mass shows a low mean apparent diffusion coefficient value (0.89 × 10−3 mm2/sec) and was assessed as BI-RADS category 4, suspicious on DW MRI. B. Craniocaudal view mammography shows a heterogeneously dense breast with no suspicious findings. The lesion was also negative on US (not shown), and combined mammography and whole-breast US showed BI-RADS category 1, negative. C. Targeted US after MRI shows a subtle indistinct hypoechoic mass (arrows) in the corresponding area on DW MRI. US-guided needle localization and surgery revealed a low-grade ductal carcinoma in situ. BI-RADS = Breast Imaging Reporting and Data System, DW = diffusion-weighted, US = ultrasound

Fig. 5. Images of a 50-year-old woman with a 6.6-cm ductal carcinoma in situ in the left breast (patient no. 17 in Table 2).

A. Axial image from DW MRI (b = 1000 sec/mm2) showed no suspicious focal hyperintensity in the breast, which was assigned a BI-RADS category 1, negative. B. Craniocaudal view mammography shows a 1.0-cm group of pleomorphic calcifications (arrow) in the outer breast, which was assessed as BI-RADS category 4, suspicious. C. US shows an indistinct hypoechoic mass with calcifications (arrow) in the area corresponding to mammography. The combined mammography and US assessment showed BI-RADS category 4, suspicious. US-guided needle localization and surgery revealed an intermediate-grade ductal carcinoma in situ. BI-RADS = Breast Imaging Reporting and Data System, DW = diffusion-weighted, US = ultrasound