Segmentation with keras

Hi, I am currently trying to use segmentation for endomentrial cancer in MRI images. I have data which is 3D, but for starters I am trying to segment the slices where there is cancer. Meaning I am only using the 2D slice where the cancer is, and the slices which are segmented by hand. I used Unet for this, but I am having troubles visualizing my result. I get the error:
“AttributeError: ‘Tensor’ object has no attribute ‘output’” when I have tried different methods to visualize the output. I am using Keras with Tensorflow. Hope someone can help me. Thanks!