MRI Screening of <i>BRCA</i> Mutation Carriers: Comparison of Standard Protocol and Abbreviated Protocols With and Without T2-Weighted Images.

Abstract

<b>BACKGROUND.</b> Increasing evidence supports the role of abbreviated MRI protocols for breast cancer detection. However, abbreviated protocols have been poorly studied in patients who are <i>BRCA1</i> or <i>BRCA2</i> mutation carriers. Furthermore, the need for T2-weighted sequences in abbreviated protocols remains controversial. <b>OBJECTIVE.</b> The purpose of this study was to compare, in the evaluation of patients with <i>BRCA</i> mutations, the diagnostic performance of a standard full breast MRI protocol with the performance of abbreviated protocols that included and did not include a T2-weighted sequence. <b>METHODS.</b> This retrospective study included 292 patients (mean age, 47.9 years) who were <i>BRCA1</i> or <i>BRCA2</i> mutation carriers who underwent 427 screening breast MRI examinations according to a standard full protocol who could be classified as having benign (<i>n</i> = 407) or malignant (<i>n</i> = 20) findings based on histopathology or imaging follow-up. Four readers independently assessed examinations in three separate sessions (theoretic abbreviated protocol, which included the first postcontrast acquisition; theoretic abbreviated protocol with addition of a T2-weighted sequence; and the standard full protocol) and assigned BI-RADS categories. Categories 3-5 were considered to represent positive examinations. Interreader agreement was assessed, and diagnostic performance was compared by use of pooled reader data. <b>RESULTS.</b> Interreader agreement on BI-RADS category, expressed as kappa values, was 0.55 for the standard, 0.45 for the abbreviated, and 0.57 for the abbreviated plus T2-weighted protocols. Pooled sensitivity was 94% for the standard, 92% for the abbreviated, and 90% for the abbreviated plus T2-weighted protocols (all <i>p</i> > .001). Pooled specificity was 80% for the standard, 71% for the abbreviated, and 83% for the abbreviated plus T2-weighted protocols (<i>p</i> < .001 for abbreviated plus T2-weighted compared with both standard and abbreviated). Pooled PPV was 19% for the standard, 14% for the abbreviated, and 20% for the abbreviated plus T2-weighted protocols (<i>p</i> < .001 for abbreviated compared with both standard and abbreviated). Pooled NPV was 100% for the standard, 99% for the abbreviated, and 99% for the abbreviated plus T2-weighted (all <i>p</i> > .001) protocols. Pooled accuracy was 80% for the standard, 73% for the abbreviated, and 83% for the abbreviated plus T2-weighted protocols (<i>p</i> < .001 for abbreviated compared with both standard and abbreviated plus T2-weighted). <b>CONCLUSION.</b> The abbreviated protocol without T2-weighted imaging had suboptimal performance. However, addition of the T2-weighted sequence yielded comparable sensitivity and accuracy and a small increase in specificity compared with the full protocol. <b>CLINICAL IMPACT.</b> The findings support implementation of abbreviated MRI with T2-weighted imaging for breast cancer screening of patients with <i>BRCA</i> mutations.