Dice without background

[ouyuxuanbridge]

When I am using this model, following (https://github.com/Project-MONAI/tutorials/blob/master/3d_segmentation/unetr_btcv_segmentation_3d.ipynb)

I don't want to include background, so I make this change:
dice_metric = DiceMetric(include_background=True, reduction="mean", get_not_nans=False)

But then dice become 0?

Could you help me please?
Thanks!

[Nic-Ma]

Hi @Ouyuxuan623 ,

Thanks for your interest here.
If you don't want to include background, why you set include_background=True?

Thanks.

[giemmecci]

Hi @Ouyuxuan623 ,

Thanks for your interest here. If you don't want to include background, why you set include_background=True?

Thanks.

Hi, @Nic-Ma,
I've found this thread looking for clarifications on various metrics, and I find the description of the "include_background" parameter given in the documentation counterintuitive, which could explain the confusion for the original poster.

From the documentation:

include_background (bool) – whether to skip Dice computation on the first channel of the predicted output. Defaults to True.

To me, this means that if I set "True" I will skip the Dice computation on the first channel ("whether to skip" -> True -> will be skipped).

I think writing the documentation as:

include_background (bool) – whether to skip perform Dice computation on the first channel of the predicted output. Defaults to True.

Or something similar, would probably clarify any doubts.

Thanks!

[KumoLiu]

Thanks for the advice, just create a PR to fix it.