Background Parenchymal Enhancement on Baseline Screening Breast MRI: Impact on Biopsy Rate and Short-Interval Follow-Up

Abstract

in the breast parenchyma during the menstrual cycle [4][5][6]. Estrogen has been shown to exert a histamine-like effect that causes an increase in microvascular permeability and vasodilation, and progesterone exerts a mitogenic effect that may increase metabolic activity, also resulting in an increase in perfusion [7,8].The detection of malignancy at MRI is based on the fact that tumors show neovascularity, with increased blood flow and increased vascular leakiness, and relies on the differential enhancement between neoplastic tissue and normal breast parenchyma [9][10][11][12][13]. It has been postulated that benign enhancement may obscure the detection of small cancers by masking this difference. In addition, although MRI is very sensitive for the detection of malignancy, specificity is somewhat Wo m e n's I m ag i ng • O r ig i n a l R e s e a rc h CMEThis article is available for CME credit. See www.arrs.org for more information. 2011; 196:218-224 0361-803X/11/1961-218 © American Roentgen Ray Society B ackground parenchymal enhancement on breast MRI refers to the normal enhancement of the patient's fibroglandular tissue seen on the first contrast-enhanced image. Background enhancement is due to the increase in T1 relaxation of tissue that occurs after gadolinium administration, and the degree of enhancement is directly related to vascular supply and permeability. Background parenchymal enhancement is thought to be related to endogenous hormone status and fluctuates with the menstrual cycle, being highest during weeks 1 and 4 and lowest during week 2 [1,2]. It increases in postmenopausal women receiving hormone replacement therapy (HRT) [3]. Changes in background parenchymal enhancement likely correlate to hormone-dependent histopathologic changes that occur Keywords: background parenchymal enhancement, BI-RADS category 3, MRI breast biopsy rate, screening breast MRI DOI:10.2214/AJR.10.4550 AJRReceived March 3, 2010; accepted after revision June 6, 2010. W O M E N ' S I M A G I N GOBJECTIVE. Background parenchymal enhancement on breast MRI refers to normal enhancement of the patient's fibroglandular tissue. The aim of this study was to determine the effect of background parenchymal enhancement on short-interval follow-up, biopsy, and cancer detection rate on baseline screening MRI in a high-risk group.MATERIALS AND METHODS. Two hundred fifty baseline high-risk screening MRI examinations were reviewed. For each, the background parenchymal enhancement pattern was recorded (minimal, ≤ 25%; mild, 26-50%; moderate, 51-75%; and marked, > 75%), as were BI-RADS category, biopsy rate, and final pathology result. Results were compared for each enhancement category.RESULTS. Of the 250 MRI examinations, 24.8% showed minimal enhancement; 34%, mild; 24%, moderate; and 17.2%, marked enhancement. Women with minimal enhancement had a significantly higher number of BI-RADS categories 1 and 2 examinations (64.5%) than women with mild (38.8%), moderate (40%), or marked (25.6%) enhancement. The BI-RADS category 3 rate was 43....

Is Breast Background Parenchymal Enhancement on MRI Related to BI-RADS Score and Follow-Up Rate?

“…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 [4]. They showed an association of short-interval follow-ups with BPE levels but the rate of BIRADS 3 in their study was greater than usual (43.6%).…”

“…In agreement with Hambly et al [4], biopsy rates did not correlate with BPE in our study. Yet, it was associated with BPE in sub-groups of premenopausal women and in women living their third decade although the PPV for biopsy was limited.…”

“…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 [13]. However, in a study by Hambly in women with minimal BPE, no significant difference in BI-RADS category for women with mild, moderate, or marked BPE was found [4].…”

“…BPE may represent blood flow and hormonal activity of dense tissue [2]. Histamine-like effects of estrogen cause vasodilation and increase breast tissue vascular permeability, and the proliferative effects of progesterone increase metabolic activity resulting in increased perfusion of breast [3] [4]. BPE is higher in younger women with hormonally active breasts [5] [6].…”

“…Some authors have suggested that an increased BPE has the possibility to obscure breast lesions and decrease MRI sensitivity for detection of BC or may even be misinterpreted as a suspicious finding itself, thus leading to an increased false-positive biopsy rate and short-interval follow-up rate [4] [10] [11] [12], but some others believe BPE does not significantly affect the diagnostic accuracy of breast MRIs [13]. Imaging material and hormonal status also affect BPE and can limit breast MRI interpretation [14] [15].…”