Validity of the minimal resistance index for discrimination between benign and malignant breast tumours

We investigated the validity of the flow parameter minimal resistance index (min RI) for discrimination of breast tumours. Colour and spectral Doppler sonography was performed on 114 patients. An increase in number of tumour vessels was paralleled by a significant drop of the minimal (min) RI (p=0.004) and increase of the maximal (max) RI (p=0.03) while mean RI was not influenced. The present results question the validity of min RI as parameter for discrimination of breast tumours. Min RI does not represent the actual flow resistance.