Breast background parenchymal enhancement MRI

1. Background parenchymal
enhancement in breast MRI before and
after neoadjuvant chemotherapy:
correlation with tumour response
Eur Radiol (2016) 26:1590–1596
By
DR. Naglaa Mahmoud
KCCC

2. Objectives
To correlate the decrease in background
parenchymal enhancement (BPE) and tumour
response measured with MRI in breast cancer
patients treated with neoadjuvant
chemotherapy (NAC).

3. Introduction

4. Contrast enhancement of fibroglandular tissue on
magnetic resonance imaging (MRI) of the female
breast is referred to as background parenchymal
enhancement (BPE).
The amount of BPE is classified as minimal, mild,
moderate or marked according to the BI-RADS®
lexicon.
Although there are similarities in the
classifications, it was shown that BPE does not
correlate with the mammographic breast density.

5. In contrast-enhanced breast MRI, BPE is known
to be influenced by the hormonal status of the
patient.
BPE itself influences the accuracy of the
radiologist’s tumour size estimation, with
inaccurate estimation of the tumour size found
in patients with moderate and marked BPE.

6. The influence of breast cancer treatment on the
degree of BPE has been previously investigated.
In addition to surgical therapy, radiation,
chemotherapy and antihormonal medications are
well established in the treatment of breast cancer.
It was previously shown that whole breast radiation
after breast conserving therapy was associated with
a decrease of BPE in the irradiated breast.
A reduction of BPE in the contralateral breast was
also observed.

7. However, many of the patients were treated not
with radiotherapy alone but with additional
chemotherapy or antihormonal medication.
Hence, the reduction of BPE may have been
caused by any of these therapies or by their
combination.
A quantitatively measured reduction of BPE by
neoadjuvant chemotherapy (NAC) in the
contralateral breast has already been shown.

8. An almost complete suppression of BPE due to
Taxane containing NAC was observed in another
study.
A reduction of BPE due to antihormonal
medication has also been shown.
A reduction of BPE due to aromatase inhibitor
therapy was observed in approximately one-third
of the patients treated.

9. The decrease in BPE following Tamoxifen
treatment was observed in the first 90 days of the
treatment but did not significantly decrease any
further thereafter.
Additionally, this effect was partly reversible
because BPE increased again after the switch from
Tamoxifen to an aromatase inhibitor, which
caused a smaller reduction of BPE.

10. In the present study, none of the patients
received any treatment other than
chemotherapy before surgery.
Thus, the aim of this study was to analyse the
effects of NAC alone on BPE, as classified
according to the BI-RADS® 2013 categories, and
to analyse the relationship between the change
in BPE and tumour response.

11. Materials and methods

12. All patients who presented with biopsy-proven breast
cancer during a time period of 24 months were analysed to
identify those who received NAC.
73 patients with 80 breast cancers treated with NAC were
retrospectively reviewed.
The inclusion criteria were that the patient received at least
6 cycles of chemotherapy and that MRI data were available
from both before and after NAC.
The mean patient age at the time of the breast cancer
diagnosis was 48.5±9.9 years (26.8–71.2 years).

13. The pre- or postmenopausal status of the
patients was noted, as were the tumour
characteristics, such as the cancer type (invasive
ductal, invasive lobular or other carcinomas),
hormone receptor status (oestrogen (ER),
progesterone (PR), human epidermal growth
factor receptor 2 (HER2) and nodal status.
Because all of the patients had biopsy proven
breast cancer, MRI was performed regardless of
the menstrual cycle to avoid a delay in
treatment.

14. Breast magnetic resonance
imaging (MRI) technique

15. MRI of the breast was performed using a 1.5 T MRI imager
(Philips Achieva, Hamburg, Germany) with a dedicated
7channel breast coil.
After a T2w STIR sequence in the transverse plane
(repetition time, 3,200 ms; echo time, 50 ms; inversion time,
160 ms; matrix, 512×512 pixels; field of view, 360 mm; slice
thickness, 3.5 mm), T1w gradient echo sequences (repetition
time, 7.5 ms; echo time, 3.7 ms; matrix, 512×512 pixels; field
of view, 400 mm; flip angle, 20°; slice thickness, 1.5 mm)
were acquired before and after intravenous (IV) injection of
0.16 mmol/kg body weight of gadolinium contrast medium
(Gadobutrol, Gadovist®, Bayer HealthCare AG, Berlin,
Germany).

16. Eight measurements were performed:
One before and seven after contrast agent
injection.
Subtraction images were produced using the
images obtained approximately 150 s after
injection and at the start of the injection (0 s).
Maximum intensity projections (MIP) were
obtained in the transverse, coronal and sagittal
planes.

17. Data analysis

18. All images from the 73 included patients were reviewed
by two radiologists (BW and HP) who, respectively, had 8
and 3 years of experience reading breast MR images.
The readers were aware that the patients had undergone
NAC because of breast cancer and reviewed the data sets
consecutively to determine the changes in BPE after NAC.
BPE was categorised into 4 BPE categories (BEC) that
ranged from 1 to 4, which indicated minimal, mild,
moderate and marked enhancement, respectively.
The readers were blinded to the other reader's results.

20. The tumour response to NAC was classified
according to RECIST 1.1 criteria (complete
remission (CR), partial response (PR), stable
disease (SD) or progressive disease(PD).
The average (mean) baseline BPE before therapy
and the change in BPE after therapy in the cases
with a CR, PR, SD and PD were calculated and
compared to investigate whether the baseline BPE
or the change in BPE could predict the tumour
response in patients undergoing NAC.

21. Results

22. 1-Tumour characteristics and response to therapy
Histopathological analysis showed that invasive
ductal carcinoma was present in 89 % (71/80) of
the patients, invasive lobular carcinoma in 10 %
(8/80) and invasive apocrine carcinoma in 1 %
(n=1).
The receptor analysis showed that 13 of 80
carcinomas were triple-negative.

23. 1-Tumour characteristics and response to therapy
Histopathological tumour response of the 80
tumours was a CR in 15 cases (19 %), PR in 44 cases
(57 %), SD in 10 cases (13 %) and PD in 8 cases (10
%).
The morphological response was CR in 17 cases (21
%), PR in 44 cases (55 %), SD in 10 cases (13 %) and
PD in 9 cases (11 %).

25. 2-Background parenchymal enhancement
categories (BEC)

26. There was no change in BPE in 27 cases according
to reader 1 and in 25 cases according to reader 2.
A decrease in BPE was found in 53 cases according
to reader 1 and in 55 cases according to reader 2,
and neither reader noted an increase in BPE in any
case.
BPE was significantly higher in premenopausal
patients.

27. The change in BPE also differed significantly
between the groups.
Premenopausal women had a significantly greater
change, which indicated a higher reduction in BEC,
than did the non-premenopausal women, with a
mean reduction of 1.05 in premenopausal
compared with 0.50 in non premenopausal
women.

28. 3- Correlation analysis
BPE was analysed before and after NAC according to the
tumour response to investigate whether the baseline BPE
or the change in BPE could predict the tumour response
to NAC.
On average, BPE decreased by 0.87 BEC in all patients.
The correlation analysis showed a significant correlation
between the decrease in BEC and the tumour response,
which showed a stronger reduction of BPE in cases with a
better tumour response.

29. Based on the tumour response, the average
decrease in BEC was 1.3±0.099 categories for
cases with CR, 0.83±0.080 in cases with PR,
0.85±0.083 in cases with SD and 0.40±0.056 in
cases with PD.
The decrease in BEC was significantly higher in
the cases with CR than in those with PD.

32. The mean differences in BEC after NAC
subclassified based on the tumour responses is
shown.
According to reader 1, the average decrease in
BEC was 0.54 BEC in patients with PD, but
according to reader 2, it was 0.27 BEC.

34. Discussion

35. In this study, authors analysed a cohort of cancer patients
with a mean age of 48.5 years old, the majority of the
patients presented with minimal or mild BPE, which is in
agreement with the values given in the literature.
These results emphasise the fact that in contrast to X-ray
mammography, MRI has a high assessability in most
patients.
The results show that this also holds true even if the
examination is not carried out between days 7 and 14 of
the menstrual cycle because the menstrual cycle is
neglected in patients with proven breast cancer.

36. There was a significant difference in BPE in
premenopausal women compared with non-
premenopausal women.
The change in BPE also differed between the
groups, with a significantly higher decrease in
premenopausal women than in peri or
postmenopausal women.
In this study, the baseline BPE before NAC did not
predict the tumour response.

37. In the present study, the decrease in BEC after the
completion of NAC was significantly higher in the
cases showing a complete remission compared
with progressive disease, and there was a slight
but significant correlation between the tumour
response and the change in BEC.
This observation may indicate that the degree of
the change in BPE can be considered a predictor of
the tumour response, especially in cases where
the exact tumour size and extension are difficult
to measure.

38. Conclusion
The degree of decrease in BPE on contrast-
enhanced MRI in patients undergoing NAC may be
a predictor of the tumour response.
The initial amount of BPE does not serve to predict
the tumour response.
Further studies are needed to investigate the
impact of BPE measurements on the disease-free
survival and overall survival.

39. Thank youThank you