Purpose:
To evaluate the Kaiser score (KS) on magnetic resonance imaging (MRI) in patients diagnosed with breast cancer and to identify clinical, pathological, and radiological factors associated with false-negative Kaiser score.

Material and methods:
This retrospective study included 120 histopathologically proven breast cancer masses. Non-mass enhancements were excluded. The KS of each lesion was determined based on MRI features. Clinicopathologi­cal features and imaging findings were also analyzed. Univariate and multivariate regression analyses were used to identify factors associated with false-negative KS results in breast cancer diagnosis.

Results:
One hundred eleven (92%) of the cases had a KS of 5 or higher, yielding a true-positive result. Nine (8%) had a score below 5, yielding a false-negative result. In univariate regression analysis, a history of breast cancer (p = 0.008), tumor size less than 2 cm (p = 0.001), and human epidermal growth factor receptor 2 (HER2) positivity (p = 0.049) were found to be statistically significantly associated with false-negative KS. In multivariate analysis, only tumor size was found to be associated with false-negative KS (p = 0.018).

Conclusions:
The Kaiser score carries a risk of false-negative KS, especially in small tumors. Therefore, evaluation in conjunction with clinical risk factors, histopathological features, and additional imaging parameters is recommended. Furthermore, KS is a valuable decision-support tool in breast MRI.