Magnetic resonance for assessment of axillary lymph node status in early breast cancer: A systematic review and meta-analysis

Introduction Current methods of identifying axillary node metastases in breast cancer patients are highly accurate, but are associated with several adverse events. This review evaluates the diagnostic accuracy of magnetic resonance imaging (MRI) techniques for identification of axillary metastases in early stage newly diagnosed breast cancer patients.

Methods Comprehensive searches were conducted in April 2009. Study quality was assessed. Sensitivity and specificity were meta-analysed using a bivariate random effects approach, utilising pathological diagnosis via node biopsy as the comparative gold standard.

Results Based on the highest sensitivity and specificity reported in each of the nine studies evaluating MRI (n = 307 patients), mean sensitivity was 90% (95% CI: 78–96%; range 65–100%) and mean specificity 90% (95% CI: 75–96%; range 54–100%). Across five studies evaluating ultrasmall super-paramagnetic iron oxide (USPIO)-enhanced MRI (n = 93), mean sensitivity was 98% (95% CI: 61–100%) and mean specificity 96% (95% CI: 72–100%). Across three studies of gadolinium-enhanced MRI (n = 187), mean sensitivity was 88% (95% CI: 78–94%) and mean specificity 73% (95% CI: 63–81%). In the single study of in-vivo proton MR spectroscopy (n = 27), sensitivity was 65% (95% CI: 38–86%) and specificity 100% (95% CI: 69–100%).

Conclusions USPIO-enhanced MRI showed a trend towards higher sensitivity and specificity and may make a useful addition to the current diagnostic pathway. Additional larger studies with standardised methods and standardised criteria for classifying a node as positive are needed. Current estimates of sensitivity and specificity do not support replacement of SLNB with any current MRI technology in this patient group.