What Is Marked Background Parenchymal Enhancement

Background parenchymal enhancement on breast MRI refers to the normal enhancement of the patient's fibroglandular tissue seen on the start contrast-enhanced image. Background enhancement is due to the increment in T1 relaxation of tissue that occurs afterwards gadolinium assistants, and the degree of enhancement is direct related to vascular supply and permeability. Groundwork parenchymal enhancement is thought to be related to endogenous hormone status and fluctuates with the menstrual cycle, existence highest during weeks 1 and 4 and lowest during calendar week 2 [ane, 2]. Information technology increases in postmenopausal women receiving hormone replacement therapy (HRT) [3]. Changes in groundwork parenchymal enhancement likely correlate to hormone-dependent histopathologic changes that occur in the breast parenchyma during the menstrual wheel [4–6]. Estrogen has been shown to exert a histamine-like effect that causes an increase in microvascular permeability and vasodilation, and progesterone exerts a mitogenic outcome that may increase metabolic activity, also resulting in an increase in perfusion [7, eight].

The detection of malignancy at MRI is based on the fact that tumors show neovascularity, with increased claret period and increased vascular leakiness, and relies on the differential enhancement between neoplastic tissue and normal chest parenchyma [9–xiii]. Information technology 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 more limited [14]. One of the factors possibly limiting specificity is the incidence of benign enhancing lesions and benign background enhancement that may be misinterpreted equally suspicious, thereby leading to an increased imitation-positive biopsy charge per unit and short-interval follow-up rate.

Despite concerns that background parenchymal enhancement may limit MRI interpretation, very few studies directly address this event. One recent report reported that groundwork enhancement does not significantly bear on the diagnostic accuracy of breast MRI (Liu F, et al., presented at the annual meeting of the Radiological Society of North America [RSNA], 2008).

To our knowledge, no studies have been published to appointment describing the influence of background parenchymal enhancement on MRI interpretation and BI-RADS category. The aim of this study was to determine the effect of background parenchymal enhancement on the interpretation of baseline screening MRI examinations in a high-risk group specifically with respect to short-interval follow-up and biopsy rates. We also examined whether in that location was a relationship between the degree of background parenchymal enhancement and the BI-RADS category assigned.

High-Risk Screening Population

With institutional review board approval, a retrospective review was performed of all baseline high-risk screening MRI examinations performed in Memorial Sloan-Kettering Cancer Center between January 5, 2003, and February 15, 2004. The indications for screening MRI are listed in Tabular array one. Women of all ages and menopausal status were included. Women who had a prior MRI test, were undergoing extent-of-disease studies or implant assessment, or had a personal history of breast conservation therapy less than 5 years before were excluded. The latter grouping was excluded to ensure the absence of posttreatment effects. A review of the MRI database maintained in the hospital indicated that ane,194 MRI examinations were performed during the study period of which 250 (20.9%) met the inclusion criteria.

Table ane: Indications for Screening MRI in Study Population

The study subjects ranged in age from xvi to 79 years, with an average age of 48.3 years.

Breast MRI Technique

Images were acquired on a 1.five-T whole-trunk scanner (Signa Excite, GE Healthcare) using a defended surface breast ringlet. Simultaneous bilateral acquisition was used. The sequences acquired included a localizing sequence, a sagittal fat-suppressed T2-weighted sequence (TR/TE, iv,000/85; slice thickness, three mm; gap, 1 mm), and a sagittal T1-weighted 3D fast spoiled slope-echo sequence (flip angle, 35°; bandwidth, 32 kHz; field of view, eighteen–22 cm; matrix, 192 × 256; slice thickness, 3 mm; gap, 0 mm) before and iii times after a rapid bolus injection of 0.1 mmol/kg of gadopentetate dimeglumine (Magnevist, Bayer HealthCare). After image acquisition, the unenhanced images were subtracted from the first contrast-enhanced images on a pixel-by-pixel basis.

MR Epitome Estimation

Images were interpreted on a PACS monitor (Centricity, GE Healthcare) by ane of eight breast radiologists with a minimum of ane yr of experience in chest imaging. The mean number of studies interpreted past each radiologist was 31.5. Images were interpreted in conjunction with mammograms and clinical history. For each test, the radiologist assigned a BI-RADS category of ane–5, where category 1 was negative; 2, beneficial; 3, probably benign, short-term follow-up recommended; 4, suspicious; and 5, highly suggestive of malignancy. Lesions referred for biopsy generally included spiculated or irregular masses or masses showing heterogeneous or rim enhancement and nonmasslike enhancement with a linear, ductal, or segmental distribution. Classification was based primarily on lesion morphology with lesion kinetics assessed visually on three contrast-enhanced sequences. Quantitative kinetics curves were generated in specific cases at the asking of the interpreting radiologist, just computer-aided diagnosis analysis was not part of the routine cess.

Review of Reports and MR Images

Patient records were reviewed in the hospital data system and the following information was recorded: patient age; indication for MRI; BI-RADS category assigned; and, if biopsy was performed, the last pathology result. For BI-RADS iii lesions, the duration of follow-upwards was also recorded. A single BI-RADS cess was given for both breasts. If the BI-RADS assessments of the breasts differed, the highest BI-RADS category was recorded. Background parenchymal enhancement was non routinely recorded in MRI reports at the time of the initial estimation. Therefore, all MR images were retrospectively blindly reviewed by ane radiologist with 5 years' experience in radiology and i year of feel in breast radiology.

Unenhanced and contrast-enhanced T1 fatty-saturation images and subtraction images were reviewed. Groundwork parenchymal enhancement was recorded and assigned a category of 1–four, where 1 indicated minimal enhancement (≤ 25% enhancement of glandular tissue); two, mild enhancement (26–l% enhancement of glandular tissue); 3, moderate enhancement (51–75% enhancement of glandular tissue); and 4, marked enhancement (> 75% enhancement of glandular tissue). A single enhancement rating was practical for both breasts.

For the 7 women with a history of chest conservation therapy, the enhancement rating was assigned for the untreated breast. The MRI glandular design, or density, was also recorded and assigned a category of i–4, where one was used to describe fatty breasts (≤ 25% glandular); 2, breasts with scattered fibroglandular densities (26–50% glandular); 3, heterogeneously dense breasts (51–75% glandular); and 4, dense breasts (> 75% glandular).

Statistical Assay

The short-interval follow-up charge per unit, biopsy rate, and positive predictive value (PPV) of biopsy were determined both overall and for each enhancement category. A chi-square examination was used to compare groups using a statistical software program. The significance value was set at a p value of ≤ 0.05.

Background Parenchymal Enhancement and Glandular Blueprint

Of the 250 baseline high-hazard screening MRI examinations performed during the study catamenia, 62 (24.8%) showed minimal background parenchymal enhancement, 85 (34%) showed mild enhancement, sixty (24%) showed moderate enhancement, and 43 (17.2%) showed marked enhancement. Effigy 1A , 1B , 1C and 1D shows examples of background parenchymal enhancement patterns on MRI.

Of 13 women with fatty breasts, seven (53.eight%) showed minimal background parenchymal enhancement and six (46.ii%) showed mild background parenchymal enhancement, whereas none showed moderate or marked background parenchymal enhancement. Of 66 women with scattered fibroglandular densities, 30 (45.5%) showed minimal background parenchymal enhancement, 24 (36.4%) showed balmy, 10 (fifteen.2%) showed moderate, and two (iii%) showed marked background parenchymal enhancement. Of 112 women with heterogeneously dumbo breasts, 17 (fifteen.2%) showed minimal groundwork parenchymal enhancement; 38 (33.9%), mild; 33 (29.5%), moderate; and 24 (21.four%), marked groundwork parenchymal enhancement. Of 59 women with dense breasts, 8 (thirteen.vi%) showed minimal background parenchymal enhancement, and 17 (28.8%) showed balmy, moderate, and marked groundwork parenchymal enhancement.

Tabular array 2 compares background parenchymal enhancement for women with fat breasts or scattered fibroglandular densities with that for women with heterogeneously dense or dense breasts. Women with fat breasts or scattered fibroglandular densities showed significantly less groundwork parenchymal enhancement than those with heterogeneously dense or dumbo breasts. Women with heterogeneously dense or dense breasts showed significantly more background parenchymal enhancement than those with fatty breasts or scattered fibroglandular densities.

Table 2: Background Parenchymal Enhancement Compared for Chest Glandularity

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Fig. 1A —Sagittal contrast-enhanced T1-weighted subtraction MR images showing different levels of breast parenchymal enhancement. Prototype of left breast of 52-year-erstwhile woman shows minimal enhancement.

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Fig. 1B —Sagittal contrast-enhanced T1-weighted subtraction MR images showing different levels of breast parenchymal enhancement. Image of right chest of sixty-year-old woman shows balmy enhancement.

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Fig. 1C —Sagittal contrast-enhanced T1-weighted subtraction MR images showing different levels of breast parenchymal enhancement. Image of left breast of 43-yr-old adult female shows moderate enhancement.

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Fig. 1D —Sagittal contrast-enhanced T1-weighted subtraction MR images showing different levels of breast parenchymal enhancement. Paradigm of left breast of 38-year-old woman shows marked enhancement.

Background Parenchymal Enhancement and BI-RADS Category

BI-RADS ane or 2—Tabular array 3 describes the BI-RADS categories assigned both overall and subdivided by enhancement category. Overall, 108 women (43.2%) were assigned a BI-RADS category of 1 or 2 and continued routine annual screening. Women with minimal background parenchymal enhancement showed a significantly higher number of normal or beneficial examinations (BI-RADS category 1 or 2). Approximately 64% of women with minimal background parenchymal enhancement were assigned a BI-RADS category of 1 or ii versus 38.8% with mild (p = 0.002), forty% with moderate (p = 0.007), and 25.half-dozen% with marked (p < 0.001) background parenchymal enhancement. There was no significant difference between women with balmy background parenchymal enhancement and those with moderate enhancement. There was a nonsignificantly lower number of normal or benign studies for women with marked background parenchymal enhancement (25.six%) compared with those with balmy (38.8%, p = 0.14) or moderate (xl%, p = 0.thirteen) enhancement.

Tabular array iii: BI-RADS Categories Assigned Overall and past Enhancement Category

BI-RADS three—One hundred ix women (43.half dozen%) were assigned a BI-RADS category three and underwent curt-interval follow-up: The lesions for which follow-up was recommended were nonmass in 85.3% and mass in 14.7%. 80-five women (78.0%) were followed for patterns of groundwork parenchymal enhancement including stippled enhancement, scattered foci of background parenchymal enhancement, and patchy and nodular background parenchymal enhancement. Eight women (seven.3%) underwent follow-up for background parenchymal enhancement patterns with benign-appearing masses; viii women (vii.iii%), for benign-appearing masses; three (2.8%), for linear background parenchymal enhancement; and five (four.6%), for other findings. The rate of brusque-interval follow-upwards for focal findings was 9.half-dozen% (24/250 MRI examinations).

The brusk-interval follow-up rate was significantly lower for women with minimal background parenchymal enhancement: 27.4% for minimal background parenchymal enhancement versus 47.1% for mild background parenchymal enhancement (p = 0.02), 45.0% for moderate background parenchymal enhancement (p = 0.04), and 58.1% for marked background parenchymal enhancement (p = 0.002). No statistically pregnant difference in BI-RADS 3 rate was plant between women with mild groundwork parenchymal enhancement and those with moderate groundwork parenchymal enhancement. Women with marked background parenchymal enhancement had no meaning divergence in short-interval follow-up charge per unit compared with women with balmy or groundwork parenchymal moderate enhancement: 58.1% versus 47.1% (p = 0.24) and 45.0% (p = 0.xix), respectively.

Of 109 women assigned a BI-RADS category three, 51 remained as BI-RADS category 3 for 6 months, after which time 45 were converted to BI-RADS 1 or 2 and half dozen were converted to BI-RADS 4. Thirty-v remained in short-interval follow-up for 12 months, afterward which fourth dimension 28 were converted to BI-RADS 1 or 2 and 7 were converted to BI-RADS four. Ten women remained in short-interval follow-upwardly for 18 months, after which fourth dimension eight were converted to BI-RADS 1 or ii and two were converted to BI-RADS 4. Vi women remained in brusque-interval follow-upwardly for 2 years, afterwards which time all half dozen women were converted to BI-RADS 1 or 2. I woman remained in BI-RADS category 3 for 3 years before beingness assigned to BI-RADS ane or 2. Six women did not undergo brusk-interval follow-up and presented for follow-up MRI after a duration of 2 (n = ane), 3 (north = 3), 4 (north = 1), or 5 (n = 1) years. Overall, the average fourth dimension the BI-RADS assessment remained category 3 was 11.33 months.

Of the 109 women assigned to brusk-interval follow-upwards, 88 (lxxx.7%) were converted to BI-RADS one or 2. Half-dozen (5.v%) did non attend for brusque-interval follow-up but later had normal MRI examinations. Fifteen (xiii.8%) women were changed to BI-RADS 4 at a follow-upwards of 6 months (northward = 6), 12 months (due north = 7), or 18 months (n = 2) and underwent biopsy. The reasons for biopsy were new finding (due north = 6), enlargement of prior finding (n = viii), and persistence of prior finding (due north = 1). Of these, 12 biopsies were benign and iii were cancerous, giving a PPV of biopsy of 20%.

For the iii women subsequently diagnosed with malignancy, the mean interval from the initial MRI to biopsy was 8 months (range, half dozen–12 months). The first of these cases was followed for mild stippled background parenchymal enhancement, and the patient had adult a new six-mm mass at 6-month follow-up. MRI-guided biopsy yielded a tiny focus of ductal carcinoma in situ (DCIS). In the second instance, followed for moderate stippled background parenchymal enhancement, the patient had developed a new 7-mm mass after i yr and MRI-guided biopsy yielded a modest focus of invasive lobular carcinoma (ILC). The 3rd example was followed for marked diffuse stippled and clumped background parenchymal enhancement and showed a focal area of increased linear groundwork parenchymal enhancement at half dozen-month follow-up. Biopsy yielded a 3-mm focus of invasive ductal carcinoma (IDC) with associated DCIS.

The 2 invasive cancers were stage I, measured less than five mm, and were node-negative. The cancer incidence rate for lesions that were present on the initial screening MRI examination and were followed was 0.ix%. 2 of the patients who underwent brusk-interval follow-up after an initial baseline screening examination developed a new finding that proved to be cancer by the time of the follow-upwardly examination, for an overall cancer charge per unit of 2.8% in the BI-RADS 3 grouping.

Table 4 shows the issue of short-interval follow-up both overall and according to enhancement category. There was no significant deviation in upshot with the different enhancement categories. Women with moderate or marked background parenchymal enhancement had no difference in false-positive biopsy rate and were just equally likely to be converted to BI-RADS 1 or 2 compared with women with minimal or mild enhancement.

Table 4: Outcome of Short-Interval Follow-Up

BI-RADS four or 5—On the initial screening MRI examination, 33 women were assigned a BI-RADS category of 4 or 5 and biopsy was recommended, yielding a biopsy rate of thirteen.2%. Table v shows the biopsy rate and PPV of biopsy according to background parenchymal enhancement category. In that location was no significant difference in the biopsy charge per unit by background parenchymal enhancement category. The biopsy rate was viii.1% (5/62) for women with minimal background parenchymal enhancement, fourteen.1% (12/85) for those with mild, 15.0% (nine/threescore) for those with moderate, and sixteen.iii% (vii/43) for those with marked groundwork parenchymal enhancement. Nine of the 33 biopsies performed yielded a diagnosis of malignancy, giving a PPV of biopsy of 27.3%. In that location was no significant difference in the PPV of biopsy past background parenchymal enhancement category. The PPV of biopsy was 40.0% for minimal, 16.7% for balmy, 33.3% for moderate, and 28.6% for marked enhancement.

TABLE v: Biopsy Rate and Positive Predictive Value (PPV) of Biopsy Both Overall and Co-ordinate to Background Parenchymal Enhancement

Cancer Detection Charge per unit

The overall cancer detection charge per unit in the screened population on the initial examination was nine per 250 cases, 3.6%. The cancer detection charge per unit was 3.2% (two/62 cases) for minimal groundwork parenchymal enhancement, 2.4% (2/85) for balmy groundwork parenchymal enhancement, 5% (3/60 cases) for moderate background parenchymal enhancement, and 4.vii% (2/43) for marked background parenchymal enhancement. These differences did not reach statistical significance.

To our noesis, no study has notwithstanding been published showing the effect of groundwork parenchymal enhancement on MRI interpretation. The results of this study show that mild, moderate, and marked background parenchymal enhancement is associated with a lower number of normal or beneficial examinations and a higher rate of recommendation for curt-interval follow-up than minimal background parenchymal enhancement. There was no significant difference among groundwork parenchymal enhancement categories in the biopsy charge per unit, PPV of biopsy, or cancer detection rate.

Autonomously from women with minimal background parenchymal enhancement, there was no significant difference in BI-RADS category for women with balmy, moderate, or marked background parenchymal enhancement. However, there was a trend toward an increased charge per unit of BI-RADS 3 in women with marked background parenchymal enhancement. Most short-interval follow-upwards cases (78%) were for diffuse background parenchymal enhancement patterns such as stippled, patchy, or nodular groundwork parenchymal enhancement and not for focal findings such as a mass or focal nonmass enhancement.

Diffuse background parenchymal enhancement patterns and extent of enhancement are somewhat interdependent—that is, all-encompassing nodular groundwork parenchymal enhancement is more likely to occur in a adult female with marked background parenchymal enhancement than in a woman with minimal background parenchymal enhancement—and this may confound the results. It would seem likely that the rate of brusque-interval follow-up for diffuse background parenchymal enhancement patterns should increase with increasing enhancement. However, although there was a trend for a college rate of short-interval follow-up in women with marked background parenchymal enhancement, this difference was not pregnant. The fact that in that location was no significant difference between mild, moderate, and marked groundwork parenchymal enhancement may suggest that it is the pattern and non the degree of background parenchymal enhancement that affects BI-RADS assessment.

The rate of BI-RADS iii in this study (43.6%) is higher than in other previously published studies (6.6–24%) [15–20]. 1 possible reason for this difference is that many of the other studies reporting a lower short-interval follow-up rate included follow-upward MRI examinations, for which the charge per unit of BI-RADS three will be lower than for baseline MRI examinations. In addition, many of the other studies included extent-of-affliction and trouble-solving studies, not just high-chance screening studies, and then their results cannot be directly extrapolated to our patient population. All the same, a previous report by Liberman et al. [15], performed at the aforementioned institution 2 years before this one, reported a BI-RADS 3 rate of 24% in 367 high-gamble baseline MRI examinations. Information technology is unclear why the rate of short-interval follow-up increased over a 2-year catamenia. In the written report by Liberman et al., there was a high incidence of malignancy (10%) in the BI-RADS 3 category.

In our study, most BI-RADS three cases were converted to BI-RADS 1 or ii at curt-interval follow-upward after the patient's baseline background parenchymal enhancement design had been established. Every bit previously stated, 78% of BI-RADS iii cases were followed for patterns of groundwork parenchymal enhancement such as stippled, patchy, or nodular background parenchymal enhancement. Only 24 of the 109 cases assigned a category of BI-RADS 3 were followed for focal findings. The short-interval follow-upwardly rate for focal findings of 9.6% (24/250 MRI examinations) is more consequent with the results of other studies, which accept reported BI-RADS three rates of six.half dozen–24% [xv–20].

In this study, nosotros found a 2.8% overall malignancy charge per unit in the BI-RADS 3 group. Withal, ii of the 3 cancers detected at follow-upward were new findings (small subcentimeter masses) not nowadays on the initial MRI exam. The third represented progression of the findings for which brusk-interval follow-up was performed. Therefore, the actual malignancy charge per unit in findings undergoing curt-interval follow-up was 0.9% (one/109). The subtract in the malignancy rate amid lesions undergoing short-interval follow-up is likely because of increased skill of interpretation.

Different mammography, for which in that location is extensive literature published on BI-RADS 3 lesions, breast MRI is still a relatively novel technique and in that location is yet much debate about which lesions are suitable for short-interval follow-up and which lesions should be given a BI-RADS 2 reading. Previous studies take shown a cancer charge per unit of 0.six–x% in patients with findings initially classified as BI-RADS 3 [15–20]. This cancer charge per unit differs from mammography, where, by definition, BI-RADS 3 lesions are associated with a less than ii% malignancy rate [21–23].

The results of this study are encouraging in that we observed a 0.9% malignancy rate in BI-RADS 3 lesions in line with that of mammography. This malignancy charge per unit may exist artificially low, nonetheless, considering almost of the cases recommended for follow-upwards were diffuse groundwork parenchymal enhancement patterns rather than focal lesions. These findings advise that shortinterval follow-up is of piddling value in these patients and that patients with lengthened enhancement patterns should be assigned a category of BI-RADS 2 rather than BI-RADS three. However, additional inquiry is needed to further define the BI-RADS 3 category for MRI.

In that location was no significant difference in biopsy rate, PPV of biopsy, or cancer detection rate among the different background enhancement categories. These results suggest that increasing background enhancement does non lead to a decreased ability to detect cancer. This characteristic of MRI is in contrast to mammography where increased density leads to decreased sensitivity for cancer detection [24–26]. The results of other authors support this conclusion (Liu F, et al., 2008 RSNA annual meeting).

The biopsy charge per unit of thirteen.2% is inside the range of previously published studies on high-risk screening (4.4–17%) [18, 27, 28]. There was a trend toward increasing biopsy rate with increasing background enhancement, but this tendency did non reach statistical significance. The cancer detection rate in this study of 3.6% is likewise within the range previously reported past other studies on the detection of otherwise occult cancers in loftier-risk women on screening MRI (0.8–3.8%) [18, 27–33]. The cancer detection charge per unit was slightly higher for women with moderate or marked background parenchymal enhancement (v% and 4.vii%, respectively) than women with minimal or mild enhancement (3.two% and 2.4% respectively). Withal, these results are non significant and the number of cancers detected in the study is such that no significant conclusion tin be fatigued from these data. Further studies with greater numbers are necessary to determine whether there is a pregnant association between background parenchymal enhancement and cancer rate.

In our study, women with fat breasts or scattered fibroglandular densities showed significantly less enhancement than those with heterogeneously dense or dumbo breasts. These findings are in understanding with the results of a written report by Arkani-Hamed et al. [34] who described a statistically significant correlation between mammographic density and the magnitude and pattern of background parenchymal enhancement. Arkani-Hamed et al. concluded that background parenchymal enhancement may provide another measure of breast cancer take chances. Withal, from the early results of our report, it appears that increased background parenchymal enhancement, although possibly representing more hormonally sensitive breast parenchyma and therefore increased vascularity, may not be an independent risk factor for breast cancer. Furthermore, because risk of chest cancer was evenly distributed among all groundwork parenchymal enhancement groups and background parenchymal enhancement is related to chest density, density may not correspond a pregnant take a chance factor in women who accept an increased baseline gamble.

A limitation of this report is that the menopausal status, employ of HRT, and phase of menstrual bicycle were not recorded. However, the aim of the study was to determine the effect of groundwork parenchymal enhancement at initial high-risk screening test on BI-RADS category regardless of hormone status. The effect of the phase of the menstrual cycle, HRT use, and menopausal status on background parenchymal enhancement has previously been established [1–3]. Some other potential limitation is that both breasts were assigned a single BI-RADS assessment, so data regarding the breast with the lower BI-RADS category was lost. This point is of particular relevance to women assigned a BI-RADS category 4 or 5 in one breast who may have received a BI-RADS category three in the contralateral breast. In total, 33 women (thirteen.2%) were assigned a BI-RADS category four or 5, and in these women the rate of BI-RADS 3 may have been underestimated. In improver, because background parenchymal enhancement was assigned as a global rating for both breasts, nosotros did not take into account any potential differences in background parenchymal enhancement betwixt both breasts. In general, background parenchymal enhancement in both breasts should be the aforementioned with the exception of women with a history of breast conservation therapy and irradiation. Only seven women were in this category and in these cases background parenchymal enhancement was assigned to the untreated breast.

In summary, this study shows that mild, moderate, and marked background parenchymal enhancement is associated with a significantly higher rate of short-interval follow-up (BI-RADS 3) than minimal background parenchymal enhancement. In that location is no significant difference in biopsy rate or PPV of biopsy. However, the smaller number of patients undergoing biopsy lacks the statistical power to determine a significant difference and further studies are required to evaluate the touch of background background parenchymal enhancement on biopsy rate and cancer detection charge per unit. These initial results suggest, however, that different density on mammography, increasing background parenchymal enhancement does non reduce the sensitivity of MRI. However, increasing background parenchymal enhancement may lead to reduced reader confidence, causing an increased rate of brusk-interval follow-up. Further enquiry is needed to clarify the BI-RADS 3 category and the effect of groundwork parenchymal enhancement on cancer detection.

Address correspondence to N. M. Hambly ([email protected]).

CME

This article is bachelor for CME credit. See world wide web.arrs.org for more information.

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