Kaiser score: breast MRI classification flowchart

Last revised by Andrew Murphy on 23 Mar 2023

The Kaiser score is an evidence-based clinical decision rule to distinguish benign from malignant lesions in breast MRI. It incorporates five BI-RADS descriptors:

  • spiculations
    • suspicious protrusion from the lesion surface that has concave lateral aspects
    • this includes classical spiculations, even subtle ones as well as dendritic branching patterns
    • not consistent with a root sign is a tongue-like aspect with rather convex lateral aspects such as can be seen in fibroadenoma and fibroadenomatoid hyperplasia
  • breast MRI enhancement curves
    • washout: type III, suspicious
    • plateau: type II, somewhat suspicious
    • persistent: type I, rather benign
  • margins
    • circumscribed (benign) and non-circumscribed (suspicious).
    • Note that most non-mass enhancements will be non-circumscribed by definition
  • internal enhancement patterns
    • suspicious (rim-like/centripetal and heterogeneous)
    • typical benign (homogeneous and centrifugal/central enhancement)
  • edema
    • defined as increased water content as visualized by T2WI/STIR sequences around the lesion
    • this finding is highly suspicious and typically associated with lymphovascular invasion and lymph node metastases

In the case of an enhancing lesion, the reader follows the flowchart in three steps, leading to a diagnostic score associated with an increased risk of malignancy, ranging from 1 (minimum) to 11 (maximum). Diagnostic decisions and subsequent clinical recommendations should always consider the clinical situation and other imaging findings. As a rule of thumb, scores >4 should be biopsied.

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