Abstract
PurposeTo investigate prevalence, malignancy rates, imaging features, and follow-up intervals for probably benign (BI-RADS 3) lesions on breast magnetic resonance imaging (MRI).MethodsA 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.ResultsFifteen 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.ConclusionWhile 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.
Highlights
The Breast Imaging and Reporting Data System (BI-RADS) has been published by the American College of Radiology in order to provide a standardised description and categorisation of breast lesions on mammography, ultrasound, and magnetic resonance (MR) imaging [1].Breast lesions classified as probably benign (BI-RADS 3) on MR imaging should have a less than two percent frequency of malignancy
The prevalence of BI-RADS 3 lesions on breast magnetic resonance imaging (MRI) ranged from 1.2-24.3%
Malignant lesions were diagnosed at follow-up time points up to 24 months
Summary
The Breast Imaging and Reporting Data System (BI-RADS) has been published by the American College of Radiology in order to provide a standardised description and categorisation of breast lesions on mammography, ultrasound, and magnetic resonance (MR) imaging [1]. Breast lesions classified as probably benign (BI-RADS 3) on MR imaging should have a less than two percent frequency of malignancy. These lesions should undergo short-term follow-up with an appropriate methodology to exclude malignancy, rather than being biopsied. The probably benign (BIRADS 3) category in breast MR imaging is assigned based on the reporting radiologist’s discretion. The resulting malignancy rates and specific imaging features of probably benign (BI-RADS 3) breast lesions on MR imaging remain a matter of debate [1]
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