Saving segmentation output for U-net

Hi, I’m currently training a U-net for lung nodule detection. I would like to store the segmented results to use it for classification of whether the nodule itself is cancerous. My question is, how do you usually save the segmented results? Previously in Keras, I saved the output file as an .npy files for each slice. For instance, slice001.npy, slice002.npy …
I would then concatenate all of the slices for classification. But is there a smarter way?