In this case, why would a lesion be alternately better seen on the CC view and then the MLO view? Would you not expect to see it equally well on all views if it is a mass lesion?
The relative projection affects the appearance of a lesion of both views. This case has a moderatley dense heterogeneous parenchyma. The degree of compression and positioning affects how the lesion is projected amongst the glandular background of the breast parenchyma. This is the basis of the rolled CC and SL vies when working up of parenchymal asymmetries.
MLO view Lt breast 2010 with a 2ndannotated view.
Very subtle asymmetry with "runners' developing. Seen on the MLO view not the CC view. Note the development of slender "runners" radiating form the small mass lesion?