Figure 4 : Two examples of cases in which tumour diameter measurement might be challenging. Case (A) shows a round mass with irregular contours at baseline breast MRI. After treatment, the mass has reduced and only scattered foci of enhancement are present in the tumour bed. Case (B) shows a highly irregular mass with spiculae, which does not significantly reduce after treatment. However, the prominent spiculations might suggest an extensive intraductal component and an accurate tumour diameter measurement is difficult in this case. Interestingly, both cases showed a Miller and Payne regression grade of 3.