Requesting new metric to calculate volume difference for small fluid volume --> Absolute Volume Difference (AVD) #4009

Is your feature request related to a problem? Please describe.
A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
In 3D Image segmentation tasks, Dice Score is known to be overly sensitive to cases with small fluid volume. Therefore it is not the right metric to do performance analysis. Whereas AVD directly reflects volume size discrepancies.

Reference: RETOUCH: The Retinal OCT Fluid Detection and Segmentation Benchmark and Challenge

Describe the solution you'd like
For small fluid volume, there should be a metric that directly gives absolute volume difference.

def AVD_Metric(y, y_pred):
  return torch.abs(torch.sub(torch.abs(y_pred),torch.abs(y)))

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.
Currently, I need to manually implement it

Additional context
Add any other context or screenshots about the feature request here.