Evaluation

Hi,

This is a sentence from the "Tasks and Evaluation" page.
"Score 1 means that the pathologist counted less than 6 mitoses in 10 consecutive microscope high power fields (an area of approximately 2 mm2)."
Does this mean that if a ROI has 10 or more HPFs then we can use this only one ROI for assigning a score to the WSI? If this is not right then how many ROIs do we need to get 10 consecutive HPFs? Also what exactly "consecutive" means here?

Thanks,
Noorul Wahab

Hi Noorul, This is how pathologists produce the mitotic grade. In essence, it is an estimate of the density of mitotic figures in the tumor. The density is, however, not estimated for the entire tumor, but for areas where it is likely to have the highest value. This is what the ROI annotations are - areas where pathologists would perform mitosis counting in the tissue. The guidelines for selecting the ROIs are roughly: "select an area that encompasses the most invasive part of the tumor, at the periphery and with highest cellularity." To answer your question, the ROI that you base your mitotic figures density estimation on does not have to necessarily be 2mm2 as long as it give you good estimate of the proliferation. "Consecutive" just means that it is one connected regions. Le me know if you have more questions.

Hi Mitko,
That was very helpful. Can you just comment on my below understanding so far:
The proliferation score assigned by the pathologists to each of the 500 WSI (training set) is based on the mitotic count they performed on ONLY ONE ROI (i-e 10 consecutive HPFs) selected per WSI. And the ROI needs not be one of the three ROIs (provided for 148 cases) in the auxiliary dataset for ROIs.

Yes, this is correct. Although since the ROI selection was done by following the same guidelines I would expect a good amount of overlap.

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