BUG: addressed pb if data are 4D
BUG: addressed pb if data are 4D

Former-commit-id: 4d1fe0ee66335cdf17c2c687346857c005a2fd32
Former-commit-id: d290d3272bbfd533a34e968fa8dd4ec7dd1c7ea2
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox