To figure out if it is this issue :
if `gadgetron --info` returns matlab not supported
and
if you type in the console :
`matlab -batch gadgetron.external.test_available`
if matlab works it will return : Gadgetron External Matlab Module
If you have an export of BART in your bashrc it will mess with the call to matlab of gadgetron (gadgetron call a 'matlab' file in the bart folder).