Breast MRI Reporting With the Kaiser Score: Worked Examples

The Kaiser Score combines morphology and enhancement kinetics of a contrast-enhancing lesion on technically adequate multiparametric breast MRI in an 11-point decision tree. It does not replace assessment of the whole breast examination, the final BI-RADS category, pathology, or clinical decision-making. The reports below are fictional.

Complete report framework

Examination: [Bilateral contrast-enhanced breast MRI; sequences, dynamic series, and diffusion].
Indication: [Screening / problem solving / staging; risk and relevant clinical history].
Comparison: [Mammography, ultrasound, and prior MRI dates / none].

Technique: [Breast coil, positioning, fat-suppressed T2, precontrast and dynamic postcontrast T1; DWI/ADC]. [State motion, omitted series, or other limitation.]

Breast composition and background parenchymal enhancement: [BI-RADS terms].
Right breast: [Mass/non-mass enhancement, side, clock-face location, distance from nipple, three dimensions, shape, margin, internal enhancement, associated findings].
Left breast: [Same features].
Regional nodes and other findings: [Axillae and imaged structures].

Target lesion: [Enhancement present/absent; mass/non-mass; spiculation/root sign; curve; then margin, internal enhancement, or ipsilateral edema as applicable].
Kaiser Score: [1–11 with decision-tree features]. [Do not score a nonenhancing lesion.]

Impression:
1. [Key finding and side].
2. [Final BI-RADS assessment with rationale].
3. [Recommendation consistent with the BI-RADS category and local protocol].

Record the decision tree

First determine whether the lesion enhances and whether it is a mass or non-mass enhancement. If it does not enhance, the Kaiser Score is not applicable; still assess the indication and the rest of the examination. Record lesion type in the report, but it does not change the numerical endpoint in the basic 11-point decision tree.

The tree uses spiculation/root sign first, then the kinetic curve. Without spiculation, a persistent curve yields score 1 for circumscribed margins or 3 for non-circumscribed margins; a plateau curve yields 2 or 5, respectively. With washout, homogeneous/centrifugal internal enhancement yields 4 and nonhomogeneous/centripetal enhancement yields 8. With spiculation, a persistent curve yields 6; for plateau and washout curves, ipsilateral edema separates endpoints 7/10 and 9/11, respectively.

General score groupings are 1–4 low-risk (BI-RADS 2/3 phenotype), 5–7 suspicious (BI-RADS 4 phenotype), and 8–11 highly suspicious (BI-RADS 5 phenotype). These are not automatic final BI-RADS assignments. Use the complete examination, prior mammography/ultrasound, clinical finding, and any pathology concordance to set the final assessment. The basic calculator does not apply optional mammographic microcalcification or ADC modifiers.

Fictional worked reports

Low score and probably benign phenotype

Examination: Bilateral contrast-enhanced breast MRI with fat-suppressed T2, precontrast and dynamic postcontrast T1, and DWI/ADC.
Indication: Palpable right breast finding remains unresolved by mammography and ultrasound.
Comparison: Mammography and targeted ultrasound dated 2026-09-22; no prior MRI.

Findings: Scattered fibroglandular tissue with minimal symmetric background parenchymal enhancement. At right 10 o'clock, 4 cm from the nipple, there is a 9 mm oval circumscribed mass. It enhances homogeneously and demonstrates a plateau curve; no spiculation is present. No marked diffusion restriction. No suspicious enhancement in the left breast. No suspicious axillary nodes.

Kaiser Score for the target: 2 (no spiculation, plateau curve, circumscribed margin).
Impression: 9 mm circumscribed right breast mass with a low-risk Kaiser phenotype. In this fictional case, assuming concordance with the clinical and prior imaging findings, final BI-RADS 3. Short-interval imaging follow-up according to the local BI-RADS pathway.

Suspicious kinetics and internal enhancement

Examination: Bilateral contrast-enhanced breast MRI with multiplanar T2, dynamic contrast-enhanced T1, and DWI/ADC.
Indication: Further evaluation of left breast mammographic asymmetry.
Comparison: Mammography and targeted ultrasound dated 2026-10-03.

Findings: Scattered fibroglandular tissue and mild background enhancement. At left 2 o'clock, 5 cm from the nipple, there is an 18 mm irregular mass with irregular margins, heterogeneous/centripetal internal enhancement, and a washout time-intensity curve. No spiculation is identified. Restricted diffusion is present. No suspicious left axillary node or right breast finding.

Kaiser Score for the target: 8 (no spiculation, washout, nonhomogeneous/centripetal internal enhancement).
Impression: 18 mm suspicious left breast mass. In this fictional example, the complete examination and available imaging support final BI-RADS 5; image-guided tissue sampling is recommended.

These scores summarize an imaging phenotype; they do not establish a diagnosis. A low score is not reassuring by itself when there is clinical-radiologic discordance, suspicious mammographic calcification, or a technical limitation.

When inputs are incomplete

If motion degrades the dynamic series, contrast timing is inadequate, or lesion margins cannot be assessed, do not guess missing features or provide a score. State the scope, affected sequence, and effect on assessment. If BI-RADS 0 is appropriate, specify what additional evaluation is needed to complete the workup.

Reporting checklist

• Indication, comparison, technical quality, breast composition, and background enhancement are included.
• Side and location and the relevant morphology are given for each mass or non-mass finding.
• Kaiser inputs and endpoint are traceable; a nonenhancing lesion is not scored.
• One final BI-RADS assessment is based on the complete examination, with a consistent recommendation.
• Calculator output is not copied as the final report or clinical decision.

The Kaiser Score calculator structures the basic decision tree for an eligible enhancing target. For current breast imaging terminology and reporting, see what changed in BI-RADS v2025.

References

• Baltzer PAT, Dietzel M, Kaiser WA. A simple and robust classification tree for differentiation between benign and malignant lesions in MR-mammography. Eur Radiol. 2013;23(8):2051–2060. doi:10.1007/s00330-013-2804-3. Original classification-tree study (opens in a new tab)
• Dietzel M, Baltzer PAT. How to use the Kaiser score as a clinical decision rule for diagnosis in multiparametric breast MRI: a pictorial essay. Insights Imaging. 2018;9:325–335. doi:10.1007/s13244-018-0611-8. Practical implementation article (opens in a new tab)
• Istomin A, et al. Diagnostic performance of the Kaiser score for characterizing lesions on breast MRI with comparison to a multiparametric classification system. Eur J Radiol. 2021;138:109659. doi:10.1016/j.ejrad.2021.109659. Independent diagnostic validation (opens in a new tab)
• American College of Radiology. ACR BI-RADS v2025 Manual: breast MRI terminology, report organization, and assessment. ACR BI-RADS (opens in a new tab)

Clinical note: This educational content does not replace BI-RADS guidance, independent image review, or clinical judgment. The examples are fictional.