What would be “Sternum-Intermediate” distance?
The article states:


  Markers (blue stickers, approximately 1 cm in diameter) were attached
  to a point approximating the suprasternal notch and an intermediate
  position on the dorsal aspect of the left breast. The position of
  these markers and the two nipples of the model were extracted from the
  point cloud scan of the breast model through manual digitising using
  Meshlab...Three straight line distances were analysed (1. internipple,
  2. sternum-to-right nipple and 3. sternum-to-intermediate marker).


One can infer that the sternum-intermediate distance is from the sternum to the intermediate marker on the dorsal aspect of the left breast. It is not, I believe, a widely measured anatomical distance, rather one 'invented' for the purposes of the study.