4D tensor appears in NN code

[dzenanz]

https://sentry.io/organizations/kitware-data/issues/3512135111/?alert_rule_id=10511315&alert_timestamp=1660823390256&alert_type=email&environment=production&project=6196580&referrer=alert_email

for val_data in data_loader:
assert np_array.shape[0] == 1 # we are dealing with scalar images

img

{affine: array([[-1., 0., 0., 0.], [ 0., -1., 0., 0.], [ 0., 0., 1., 0.], [ 0., 0., 0., 1.]]), data: tensor([[[[0.], [0.], [0.], ..., [0.], [0.], [0.]], [[0.], [0.], [0.], ..., [0.], [0.], [0.]], [[0.], [0.], [0.], ..., [0.], [0.], [0.]], ..., [[0.], [0.], [0.], ..., [0.], [0.], [0.]], [[0.], [0.], ..., path: '/tmp/tmpxeohm_29/9a4bae7112ed27db4a74b103fb5f284b.png', stem: '9a4bae7112ed27db4a74b103fb5f284b', type: 'intensity'}