BIRADS 3 MRI lesions: Was the initial score appropriate and what is the value of the blooming sign as an additional parameter to better characterize these lesions?

Characteristics and Pathologic Results of Foci on Breast Magnetic Resonance Imaging: A Systematic Review and Meta-Analysis

BACKGROUND

Although T2-weighted imaging (T2WI) hypointensity, delayed enhancement washout pattern, interval growth, and new appearance of a focus have been associated with malignancy, the results are not consistent.

PURPOSE

To investigate the malignancy rate and identify the clinical and imaging characteristics associated with malignancy among foci in breast MRI.

STUDY TYPE

Meta-analysis.

SUBJECTS

32 articles with 2645 foci.

FIELD STRENGTH/SEQUENCE

1.5 T and 3.0 T. T1WI, T2WI, and DCE-MRI.

ASSESSMENT

PubMed, Embase, Scopus, and Cochrane databases were searched for articles published from January 2013 to December 2023, using the search terms: "focus," "foci," "small mass," "size," "breast magnetic resonance imaging," and "breast MRI." Extracted data included the reference standard, number of benign/malignant foci, size criterion, BI-RADS categories, amount of fibroglandular tissue, background parenchymal enhancement, T2WI signal intensity, delayed enhancement pattern.

STATISTICAL TESTS

Pooled data were analyzed using Revman 5.4 software. Between-study heterogeneity was investigated with I2-statistics. If I2 < 50% (reflecting no substantial heterogeneity), a fixed effects model was used for analysis. If I2 > 50%, random effects model analysis was used. For continuous variables, the standardized mean difference (SMD) and 95% confidence interval (CI) were used to represent the results. Malignancy rate of each study was transformed via the Freeman-Tukey Doublearcsine method. Odds ratios (OR) with 95% CIs were calculated for dichotomous variables. p values ≤ 0.05 were considered significant.

RESULTS

The pooled malignancy rate of 2645 foci was 16% (95% CI: 13%-19%). There was a significant association between malignant foci and older age (OR = 5.82, 95% CI: 2.08-9.56), T2WI hypointensity (OR = 2.28, 95% CI: 1.19-4.35) and delayed enhancement washout pattern (OR = 2.78, 95% CI: 1.87-4.12). Hyperintense foci were significantly more likely to be benign (OR = 0.41, 95% CI: 0.21-0.79).

DATA CONCLUSION

An enhancing focus with T2WI hypointensity and a washout pattern, especially in older patients, is significantly more likely to be malignant. Therefore, careful attention should be paid to it and could justify consideration of biopsy.

EVIDENCE LEVEL

3.

TECHNICAL EFFICACY

Stage 3.

Misdiagnosis in breast imaging: a statement paper from European Society Breast Imaging (EUSOBI)-Part 2: Main causes of errors in breast imaging and recommendations from European Society of Breast Imaging to limit misdiagnosis

IMPORTANCE

Breast cancer is one of the leading causes of negligence claims in radiology. The objective of this document is to describe the specific main causes of errors in breast imaging and provide European Society of Breast Imaging (EUSOBI) recommendations to try to minimize these.

OBSERVATIONS

Technical failures represent 17% of all mammographic diagnostic negligence claims. Mammography quality control protocol and dedicated training for technologists and radiologists are essential. Lack of consideration of the clinical context is a second critical issue, as a clinical abnormality is found in 80% of malpractice claims. EUSOBI emphasizes the importance of communication and clinical examination before the diagnostic investigation. Detection errors or misapplications of the lexicon or Breast Imaging Reporting Data System (BI-RADS) score account for 5% of malpractice claims and should be reduced by limiting radiologists' distraction or fatigue, and being aware of satisfaction of search errors and the importance of a personal systematic review. Errors related to pathological concordance and MDT review can be limited by the use of markers after biopsy and the use of standardized reports, which can aid communication with other specialities. Finally, errors related to tumor or patient factors should be discussed, considering the use of contrast-enhanced mammography and magnetic resonance imaging.

CONCLUSION

Several factors are responsible for misdiagnosis in breast cancer, including errors in the practice of the technician and/or radiologist (technical failures, lack of consideration of the clinical context, incorrect application of the BI-RADS score, false reassurances), lack of communication with other specialists or with the patient, and the type of tumor and breast parenchyma.

KEY POINTS

Question What factors most contribute to and what implications stem from misdiagnosis in breast imaging? Findings Ongoing training and education for radiologists and other healthcare providers, as well as interdisciplinary collaboration and communication is paramount. Clinical relevance Misdiagnosis in breast imaging can have significant implications for patients, healthcare providers, and the entire healthcare system.

Understanding BI-RADS Category 3

The Breast Imaging Reporting and Data System (BI-RADS) category 3 assessment is used for breast imaging findings considered "probably benign," with less than a 2% likelihood of malignancy. It is used to increase specificity by decreasing the number of breast biopsies. It has been validated for mammography, breast US, and emerging indications for use in contrast-enhanced breast MRI. Despite the long-term use of category 3 and numerous published studies that evaluate characteristic imaging findings appropriate for this category, there is still misuse and confusion regarding its accurate use. Imaging findings classified as category 3 require short-term follow-up to assess stability and identify changes that may warrant a biopsy for early diagnosis of breast cancer. Category 3 should not be used in a screening study without a comprehensive diagnostic evaluation that may reveal suspicious features or downgrade a finding to benign. In mammography, category 3 findings are validated for grouped round calcifications, oval circumscribed masses, and nonpalpable asymmetries. In US, category 3 can be applied to oval circumscribed parallel solid masses and complicated cysts. Category 3 can be assigned to clustered microcysts when they are very small or deep in the breast. Recent studies have yielded characteristic findings appropriate for MRI category 3 that are expected to be included in the sixth edition of the BI-RADS atlas. These include oval circumscribed masses with associated T2-hyperintense signal, focal non-mass enhancement, and foci of enhancement with associated T 2-hyperintense signal. Surveillance with short-interval imaging enables radiologists to monitor findings and act early when a change is detected. ©RSNA, 2024 Supplemental material is available for this article. See the invited commentary by Cohen and Leung.

Outcomes of High-Risk Breast MRI Screening in Women Without Prior History of Breast Cancer: Effectiveness Data from a Tertiary Care Center

OBJECTIVE

To evaluate the diagnostic performance outcomes of a breast MRI screening program in high-risk women without prior history of breast cancer.

METHODS

Retrospective cohort study of 1 405 consecutive screening breast MRI examinations in 681 asymptomatic women with high risk of breast cancer without prior history of breast cancer from January 1, 2015, to December 31, 2019. Outcomes (sensitivity, specificity, positive predictive value, negative predictive value, false-negative rate [FNR], cancer detection rate [CDR]) and characteristics of cancers were determined based on histopathology or 12-month follow-up. MRI examinations performed, BI-RADS assessments, pathology outcomes, and CDRs were analyzed overall and by age decade. Results in incidence screening round (MRI in last 18 months) and nonincidence round were compared.

RESULTS

Breast MRI achieved CDR 20/1000, sensitivity 93.3% (28/30), and specificity 83.4% (1 147/1375). Twenty-eight (28/1 405, CDR 20/1000) screen-detected cancers were identified: 18 (64.3%, 18/28) invasive and 10 (35.7%, 10/28) ductal carcinoma in situ. Overall, 92.9% (26/28) of all cancers were stage 0 or 1 and 89.3% (25/28) were node negative. All 14 incidence screening round malignancies were stage 0 or 1 with N0 disease. Median size for invasive carcinoma was 8.0 mm and for ductal carcinoma in situ was 9.0 mm. There were two false-negative exams for an FNR 0.1% (2/1 405).

CONCLUSION

High-risk screening breast MRI was effective at detecting early breast cancer and associated with favorable outcomes.

BI-RADS 3 Assessment on MRI: A Lesion-Based Review for Breast Radiologists

Unlike mammography and US, limited data exist to establish well-defined criteria for MRI findings that have a ≤2% likelihood of malignancy. Therefore, determining which findings are appropriate for a BI-RADS 3 assessment on MRI remains challenging and variable among breast radiologists. Emerging data suggest that BI-RADS 3 should be limited to baseline MRI examinations (or examinations with less than two years of prior comparisons) performed for high-risk screening and only used for masses with all of the typical morphological and kinetic features suggestive of a fibroadenoma or dominant enhancing T2 hypointense foci that is distinct from background parenchymal enhancement and without suspicious kinetics. This article presents an updated discussion of BI-RADS 3 assessment (probably benign) for breast MRI using current evidence.

Outcomes of Foci on Breast MRI: Features Associated With Malignancy

OBJECTIVE. The objective of this study was to determine the outcomes of foci seen on breast MRI and to evaluate imaging features associated with malignancy. MATERIALS AND METHODS. In this institutional review board-approved retrospective study, we reviewed 200 eligible foci in 179 patients that were assigned BI-RADS category of 3 or 4 from December 2004 to August 2018. Clinical and imaging features of all eligible foci were collected, and associations with malignant outcomes were evaluated. Malignancy rates were also calculated. RESULTS. Of 200 eligible foci, 64 were assigned BI-RADS category 3 and 136 were assigned BI-RADS category 4. The malignancy rate was 1.6% (1/64) among BI-RADS 3 foci and 17.6% (24/136) for BI-RADS 4 foci. The majority of malignant foci represented invasive breast cancer (68.0%, 17/25). Focus size and washout kinetics were significantly associated with malignant outcome (p < 0.05). CONCLUSION. Despite the high prevalence of foci on breast MRI, data are limited to guide their management. Foci should not be disregarded, because foci undergoing biopsy had a malignancy rate of 17.6%, with the majority of malignant foci representing invasive cancer. Larger size and washout kinetics were associated with malignancy in our study and should raise the suspicion level for a focus on breast MRI.

Breast lesions classified as probably benign (BI-RADS 3) on magnetic resonance imaging: a systematic review and meta-analysis

Purpose

To investigate prevalence, malignancy rates, imaging features, and follow-up intervals for probably benign (BI-RADS 3) lesions on breast magnetic resonance imaging (MRI).

Methods

A systematic database-review of articles published through 22/06/2016 was performed. Eligible studies reported BI-RADS 3 lesions on breast MRI. Two independent reviewers performed a literature review and data extraction. Data collection included study characteristics, number/type of BI-RADS 3 lesions, final diagnosis (histopathology and/or follow-up). Sources of bias (QUADAS-2) were assessed. Meta-analysis included data-pooling, heterogeneity testing, and meta-regression.

Results

Fifteen studies were included. Prevalence was reported in 11 studies (range: 1.2-24.3%). Malignancy rates ranged between 0.5-10.1% (pooled 61/2814, 1.6%, 95%-CI:0.9-2.3% (random-effects-model), I²=53%, P=0.007). In a subgroup of 11 studies (2183 lesions), highest malignancy rates were observed in non-mass lesions (pooled 25/714, 2.3%, 95%-CI:0.8-3.9%, I²=52%, P=0.021) followed by mass lesions (pooled 15/771, 1.5%, 95%-CI:0.7-2.4%, I²=0%, P=0.929), and foci (pooled 10/698, 1%, 95%-CI:0.3-1.7%, I²=0%, P=0.800). There was non-significant negative association between prevalence and malignancy rates (P=0.077). Malignant lesions were diagnosed at all follow-up time points.

Conclusion

While prevalence of MRI BI-RADS 3 lesions was strongly heterogeneous, pooled malignancy rates met BI-RADS benchmarks (<2%). Malignancy rates varied, exceeding 2% in non-mass lesions. Twenty-four-month surveillance is required to detect all malignant lesions.

Key points

• Probably benign (BI-RADS 3) lesions showed a pooled malignancy-rate of 1.6% (95%-CI:0.9-2.3%).

• Malignancy rates differ and are highest in non-mass lesions (2.3%, 95%-CI:0.8-3.9%).

• The prevalence of BI-RADS 3 lesions on breast MRI ranged from 1.2-24.3%.

• Malignant lesions were diagnosed at follow-up time points up to 24 months.

Differentiation of ductal carcinoma in situ versus fibrocystic changes by magnetic resonance imaging: are there pathognomonic imaging features?

Background In breast magnetic resonance imaging (MRI), the diagnosis of ductal carcinoma in situ (DCIS) remains controversial; the most challenging cause of false-positive DCIS diagnosis is fibrocystic changes (FC). Purpose To search for typical and pathognomonic patterns of DCIS and FC using a standard clinical MRI protocol. Material and Methods Consecutive patients scheduled for breast MRI (standardized protocols @ 1.5T: dynamic-T1-GRE before/after Gd-DTPA [0.1 mmol/kg body weight (BW)]; T1-TSE), with subsequent pathological sampling, were investigated. Sixteen MRI descriptors were prospectively assessed by two experienced radiologists in consensus (blinded to pathology) and explored in patients with DCIS (n = 77) or FC (n = 219). Univariate and multivariate statistics were performed to identify the accuracy of descriptors (alone, combined). Furthermore, pathognomonic descriptor-combinations with an accuracy of 100% were explored (χ² statistics; decision trees). Results Six breast MRI descriptors significantly differentiated DCIS from FC ( P_corrected < 0.05; odds ratio < 7.9). Pathognomonic imaging features were present in 33.8% (n = 100) of all cases allowing the identification of 42.9% of FC (n = 94). Conclusion Pathognomonic patterns of DCIS and FC were frequently observed in a standard clinical MRI protocol. Such imaging patterns could decrease the false-positive rate of breast MRI and hence might help to decrease the number of unnecessary biopsies in this clinically challenging subgroup.