Quantitative diffusion weighted imaging for differentiation of benign and malignant breast lesions: The influence of the choice of <i>b</i>‐values

<jats:title>Abstract</jats:title><jats:sec><jats:title>Purpose:</jats:title><jats:p>To evaluate the influence of the choice of different combinations of <jats:italic>b</jats:italic>‐values on the <jats:italic>ADC</jats:italic> and on the diagnostic performance of quantitative diffusion weighted imaging (DWI) in breast lesions.</jats:p></jats:sec><jats:sec><jats:title>Materials and Methods:</jats:title><jats:p>Seventy‐three patients (90 lesions) underwent 3 Tesla (T) breast MRI including a DWI‐scan using <jats:italic>b</jats:italic>‐values 0, 150, 499, and 1500 s/mm<jats:sup>2</jats:sup> and histological analysis. Five combinations of <jats:italic>b</jats:italic>‐values were used to calculate the <jats:italic>ADC</jats:italic>, each with different sensitivities to perfusion and diffusion effects. The median <jats:italic>ADC</jats:italic> of benign lesions, noninvasive carcinomas and invasive carcinomas and the diagnostic performance of the five methods were compared.</jats:p></jats:sec><jats:sec><jats:title>Results:</jats:title><jats:p>Eighty‐eight lesions were analyzed (37 benign, 13 noninvasive carcinomas, 38 invasive carcinomas). The median <jats:italic>ADC</jats:italic> was highest in benign lesions, intermediate in noninvasive carcinomas and lowest in invasive carcinomas for all methods. Calculating the <jats:italic>ADC</jats:italic> with the lowest 2 <jats:italic>b</jats:italic>‐values yielded the highest <jats:italic>ADC</jats:italic> for all lesions types; the highest 2 <jats:italic>b</jats:italic>‐values yielded the lowest <jats:italic>ADC</jats:italic>. The area under the receiver operating characteristic curve was approximately equal for all methods.</jats:p></jats:sec><jats:sec><jats:title>Conclusion:</jats:title><jats:p>The <jats:italic>ADC</jats:italic> of breast lesions varied substantially with the choice of different <jats:italic>b</jats:italic>‐values, indicating that absolute <jats:italic>ADC</jats:italic> threshold values to differentiate benign and malignant lesions should be interpreted with caution. However, the diagnostic performance of quantitative DWI was not affected by the choice of different <jats:italic>b</jats:italic>‐values. J. Magn. Reson. Imaging 2010;31:1100–1105. © 2010 Wiley‐Liss, Inc.</jats:p></jats:sec>