Diagnostic value of breast MRI and Kaiser score in BIRADS 0 and 4 lesions compared with histopathology and follow-up.

OBJECTIVE

Breast cancer is the most frequently diagnosed cancer type in women, and early detection and treatment significantly improve survival rates. In conventional imaging methods (mammography and ultrasound), lesions classified as BI-RADS 0 or 4 often lead to a high rate of unnecessary biopsies, resulting in both superfluous invasive procedures for patients and increased costs for the healthcare system. The aim of our study is to investigate the diagnostic validity of the Kaiser score in predicting malignancy in patients who underwent breast MRI following inconclusive or suspicious findings (BI-RADS 0 or 4) on conventional imaging, based on pathology results or clinical follow-up.

MATERIALS AND

METHODS

Between September 2022 and April 2024, 99 patients who underwent breast MRI due to inconclusive results from conventional breast imaging methods (mammography and breast ultrasound) or the detection of suspicious findings (BI-RADS 0 or 4), and who had either histopathological evaluation following biopsy under US or MG guidance or were followed for at least 12 months, were included in this single-center retrospective study. The 99 patients included in the study were divided into two groups based on histopathology or follow-up outcomes (benign lesion group and malignant lesion group). Comparisons were made between these two groups.

RESULTS

When comparing benign and malignant groups, statistically significant differences were observed for age (p < 0,001), age at menarche (p = 0,004), breastfeeding status (p = 0,009), menopausal status (p = 0,017), and use of hormone replacement therapy (p = 0,036). MRI BI-RADS (p < 0,001) and Kaiser scores (p < 0,001) were notably higher in the malignant group. Kaiser score was identified as the strongest diagnostic predictor of malignancy (AUC = 0,977, 95 % CI: 0.955-0.999; p < 0,001). Using a cut-off value of Kaiser score > 5, the sensitivity and specificity were 97 % (95 % CI: 84.2 %-99.9 %) and 87.9 % (95 % CI: 77.5 %-94.6 %), respectively. The MRI BI-RADS ranked second with a cut-off value > 4 (AUC = 0.878, 95 % CI: 0.805-0.950; p < 0.001); at this threshold, the sensitivity and specificity were 60.6 % (95 % CI: 42.1 %-77.1 %) and 100 % (95 % CI: 94.6 %-100.0 %), respectively. In multivariable logistic regression, higher Kaiser score (OR = 4.25, p < 0.001) and older age (OR = 1.16, p = 0.041) were associated with higher odds of malignancy, whereas older age at menarche was associated with lower odds (OR = 0.347, p = 0.030).

CONCLUSION

For breast lesions classified as BI-RADS 0 or 4 on conventional imaging, the Kaiser score provides excellent diagnostic accuracy and may support lesion stratification when used with MRI BI-RADS assessment; biopsy decisions should remain based on integrated clinical and imaging findings.