Rotation of image using python cuts off part of image

I have written a little script that rotates an image based on a transform (.tfm) that I’ve obtained from the Slicer GUI:

def resample(image, transform):
    # Output image Origin, Spacing, Size, Direction are taken from the reference
    # image in this call to Resample
    reference_image = image
    interpolator = sitk.sitkCosineWindowedSinc
    default_value = 100.0
    return sitk.Resample(image, reference_image, transform,
                         interpolator, default_value)

fet_180 = resample(fet, rotation_180)

Works perfectly, except for the fact that the images get cut off after the rotation. Example (zoomed out for clarity:
Before rotation:

After Rotation:

This doesn’t happen when rotating in the Slicer GUI itself, what can I do to fix this?