  Histopathological prognostication of neoplasia including most tumor grading
systems are based upon a number of criteria. Probably the most important is the
number of mitotic figures which are most commonly determined as the mitotic
count (MC), i.e. number of mitotic figures within 10 consecutive high power
fields. Often the area with the highest mitotic activity is to be selected for
the MC. However, since mitotic activity is not known in advance, an arbitrary
choice of this region is considered one important cause for high variability in
the prognostication and grading.
  In this work, we present an algorithmic approach that first calculates a
mitotic cell map based upon a deep convolutional network. This map is in a
second step used to construct a mitotic activity estimate. Lastly, we select
the image segment representing the size of ten high power fields with the
overall highest mitotic activity as a region proposal for an expert MC
determination. We evaluate the approach using a dataset of 32 completely
annotated whole slide images, where 22 were used for training of the network
and 10 for test. We find a correlation of r=0.936 in mitotic count estimate.
