Objective: We investigated the correlations between background parenchymal enhancement (BPE) and MRI interpretations with respect to short-interval follow-ups and biopsy rates. Methods: All accessible MRI examinations from 128 women during a limited time period in 2016 were evaluated. A blinded radiologist visually categorized BPE as minimal, mild, moderate, or marked. A BI-RADS category was also assigned. We used descriptive statistics to report the findings and chi-square and Fisher’s exact tests to compare categories. Results: Prevalence of minimal, mild, moderate, and marked BPE was 14.1%, 43.0%, 32.0%, and 10.9%, respectively. The short-interval follow-up rates were 22.2%, 27.3%, 26.8%, and 7.1% in women with minimal, mild, moderate, and marked BPE, respectively. BPE was not associated with the short-interval follow-up rate (p-value = 0.477). Biopsy rates were 22.2%, 27.3%, 22.0%, and 57.1% in women with minimal, mild, moderate, and marked BPE, respectively. Although there was no significant relationship between biopsy rates and BPE levels (p-value = 0.095) in the total population, these two factors were significantly associated in premenopausal women (p-value = 0.023) and in women of 30 - 39 years (p-value = 0.001). Conclusion: Higher BPE does not correlate with short-interval follow-up rates, but appears to be related to biopsy rate, thus causing false-positives and unnecessary biopsy recommendations, particularly in younger, premenopausal women.
Background parenchymal enhancement (BPE), representing normal fibro-glandular tissue enhancement in dynamic contrast-enhanced magnetic resonance imaging (MRI), corresponds to hormonally responsive glandular tissue [
MRI is the most sensitive imaging method for detection of breast cancer (BC), yet it has limited specificity [
Design: From January 2016 to January 2017 and after taking written informed consents, we randomly included 128 women who had breast MRI in a tertiary referral hospital to investigate the correlation between BPE and BI-RADS score. All MRI images retrospectively were observed by a specialized breast radiologist. Indications for breast MRI were questionable mammographic or ultra-sonographic findings, unexplainable clinical findings, BIRADS 3 lesions’ follow-ups, and planning for 12 new cases of biopsy-proven malignancies. The exclusion criteria consisted of a history of conservative breast surgery, chemotherapy, radiotherapy, and/or hormone replacement therapy.
In a dedicated surface breast coil, the same techniques for all patients were performed in a 1.5 Tesla MRI scanner, and a blinded expert breast radiologist reviewed all of the images. Localization, T1-weighted non-fat-suppressed sequences, and T2-weighted fat-suppressed sequences were conducted following standard protocols, and six sequences after injection of 0.1 mmol/L gadopentetate dimeglumine (Magnevist, Bayer and Germany) were then obtained and subtracted pixel-by-pixel from the first non-contrast images. The radiologist visually assessed BPE in post-contrast fat-suppressed T1-weighted subtracted images and categorized BPE on the basis of fifth edition of BI-RADS criteria as minimal, mild, moderate, or marked [
BI-RADS categories consisted of 6 groups: 0 (incomplete assessment, recall); 1 (normal findings, routine screening); 2 (benign findings, routine screening); 3 (probably benign findings, short-interval follow-up); 4 (suspicious findings, biopsy); 5 (highly-suspicious findings, biopsy); and 6 (biopsy-proven malignancy, excision). Biopsies were taken with a Tru-cut needle from patients who had been recommended for a biopsy based on BI-RADS 4 or 5 which was given by another radiologist who was blind to the study. Following standard protocols, an expert pathologist examined breast specimens’ biopsies from patients who had been classified as BI-RADS 4 or 5 (Figures 1-3).
Data analysis: We used descriptive statistics (count, frequency distributions) to report BI-RADS categories, short-interval follow-up and biopsy rates, and positive predictive biopsy value (PPV). Comparing categories, we used chi-square and Fisher’s exact tests. Type I error was considered 0.05. The data was collected on MS Office Excel datasheets (Microsoft, Redmond, USA). All analyses were conducted using SPSS v.22 (IBM Corp., Armonk, USA).
Ethical considerations: The study protocol was evaluated and approved by the Atieh hospital institutional ethics committee considering the retrospective setting of the study and taking written informed consents from patients for using their data.
Confidentiality of information was followed. Researchers caused no adverse or harmful events to patients. Authors were committed to the principles of the Declaration of Helsinki and declared no conflicts of interests.
We studied 89 (69.5%) pre-menopausal and 39 (30.5%) postmenopausal women aged 18 to 74 years old. Approximately a third of the women (count = 44) were aged 30 - 39 years. Minimal, mild, moderate, and marked BPE were observed in 18 (14.1%), 55 (43.0%), 41 (32.0%), and 14 (10.9%) women, respectively.
BPE and BI-RADS score level,
BPE and short term follow up, overall, 49 women (38.3%) presented with normal or benign examinations (such as BI-RADS 1 or 2) and continued routine screening. About 55% of women with minimal BPE were assigned a BI-RADS category of 1 or 2 versus 36.4%, 39.0%, and 21.4% of women with mild, moderate, and marked BPE, respectively (
As shown in
Background Parenchymal Enhancementa | |||||
---|---|---|---|---|---|
BI-RADS category | Totala | Minimal (n = 18) | Mild (n = 55) | Moderate (n = 41) | Marked (n = 14) |
1) Normal findings | 5 (3.9) | 3 (16.7) | 1 (1.8) | 0 (0.0) | 1 (7.1) |
2) Benign findings | 44 (34.4) | 7 (38.9) | 19 (34.5) | 16 (39.0) | 2 (14.3) |
3) Probably benign findings | 31 (24.2) | 4 (22.2) | 15 (27.3) | 11 (26.8) | 1 (7.1) |
4) Suspicious findings | 32 (25.0) | 2 (11.1) | 13 (23.6) | 9 (22.0) | 8 (57.1) |
5) Highly-suspicious findings | 4 (3.1) | 2 (11.1) | 2 (3.6) | 0 (0.0) | 0 (0.0) |
6) Biopsy-proven malignancy | 12 (9.4) | 0 (0.0) | 5 (9.1) | 5 (12.2) | 2 (14.3) |
BI-RADS: breast imaging-reporting and data system, n: count. anumbers represent “count (percentage within each column)”.
Background Parenchymal Enhancemente | ||||||
---|---|---|---|---|---|---|
MRI interpretation | Totale | Minimal, n = 18 | Mild, n = 55 | Moderate, n = 41 | Marked, n = 14 | p-value* |
Recommended routine screeninga | 38.3 (49) | 55.6 (10) | 36.4 (20) | 39.0 (16) | 21.4 (3) | 0.274 |
Recommended short-interval follow-upb | 24.2 (31) | 22.2 (4) | 27.3 (15) | 26.8 (11) | 7.1 (1) | 0.477 |
Recommended biopsyc | 28.1 (36) | 22.2 (4) | 27.3 (15) | 22.0 (9) | 57.1 (8) | 0.095 |
PPV for biopsyd | 16.7 (6) | 50.0 (2) | 20.0 (3) | 0.0 (0) | 12.5 (1) | 0.107 |
n: count, PPV: positive predictive value; aBI-RADS 1 or 2; bBI-RADS 3; cBI-RADS 4 or 5; dpercentage of malignant lesions detected in women who underwent biopsy; enumbers represent “percentage within each column (count)”; *Fisher’s exact test.
mild, moderate, and marked BPE, respectively. BPE was not associated with short-interval follow-up rates (p-value = 0.477).
BPE and biopsy, biopsies were recommended for 36 women (28.1%) with BI-RADS category of 4 or 5.
Biopsies proved the presence of malignancies (invasive ductal carcinoma) in six patients, giving a PPV of 16.7%. PPV for biopsy did not associate with BPE in the total population (p-value = 0.107).
According to sub-analyses, PPV for biopsy was 16.7% in both premenopausal (4/24) and postmenopausal (2/12) women and 8.3% (1/12) in women aged 30 - 39 years. PPV for biopsy and age decade were not associated (Fisher’s exact p-value = 0.318).
Few studies have evaluated the impact of BPE on MRI diagnostic performance. In our study, BPE associated with BI-RADS scores in all women, including premenopausal ones and women aged 30 - 39 years. De Martini et al. reported that abnormal interpretation rates for women with moderate or marked BPE were significantly higher than that for women with minimal or mild BPE, but positive biopsy rates were not affected by different BPE [
In contrast to the De Martini et al. study [
Almost quarter of our subjects underwent short-interval follow-ups and rates of short-interval follow-ups did not associate with BPE; these results are in contrast to the previous Hambly study [
In agreement with Hambly et al. [
Only one out of six biopsies revealed a malignancy in our study. In agreement with Hambly et al. and De Martini et al. [
According to low predictive values of biopsy in premenopausal women and women aged 30 - 39 years in our study, and the point that BPE is higher in younger breasts [
Our study like Hambly and colleagues [
There were some limitations to this study as: small sample size and visual qualitative BPE assessment. In addition, being a single-centered study is a challenge for making generalizations about the results. One other limitation was assigning a single BI-RADS assessment to both breasts because the breast with the lower BI-RADS category data was lost. It is especially important when women with BI-RADS category 4 or 5 in one breast had BI-RADS category 3 in the contralateral breast.
Higher BPE on breast MRIs does not correlate with short-interval follow-up rates but can increase false-positive interpretations, leading to unnecessary biopsies, particularly in younger, premenopausal women.
AA designed the concept. All authors collaborated in data acquisition. FR provided statistical advice on study design and data analyses. AA and FR analyzed and interpreted the data. SAK drafted the manuscript. All authors critically reviewed the manuscript. All authors read and approved the final manuscript. AA takes responsibility for the paper as a whole.
The authors declare that there is no conflict of interest.
This research received no specific grant from any funding agency in the public, commercial.
Alikhassi, A., Akbari, H., Yazdi, S.N.M., Kia, S.A. and Roozafzai, F. (2018) Is Breast Background Parenchymal Enhancement on MRI Related to BI-RADS Score and Follow-Up Rate? Advances in Breast Cancer Research, 7, 15-22. https://doi.org/10.4236/abcr.2018.71002