Yes, my dataset is the BraTs MRI dataset - the dataloader I have right now is for only one modality and I also think it is not correct. If I want to chunk up the data for 3D UNet then I think each voxel chunk (16*192*192)  should get put into batch dimension as (2*8 x 1 x 16 x 192 x 192 = 16x1x16x192x192 . Does that seem right?