BUG: fixed computation of CSA (issue #388)
BUG: fixed computation of CSA (issue #388)

Former-commit-id: 92d6828d29f66e629004388629cd2b60dc56e199 [formerly a8295dd00645f57c67d033fb125a4733297266eb]
Former-commit-id: 8d342563cf2f826c2b8ecc6d89a615362f1d6f7a
Former-commit-id: c4388f89efd36c1a6a3f1c4eebd885f9b834e9b5
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox