[Camino-users] anomalous high FA values

[Ian Malone]

Hi,

We're using Camino on some Siemens data, 42 directions, b=1000 s/mm^2, 
there are a few different protocols (different sites), but the problem 
seems to affect a few of them, one has 7 b=0 acquisitions. Fitting 
tensors using the non-linear least squares fit from modelfit we find a 
small number of voxels with FA>0.999, mostly in the caudate (sorry, 
don't have all the details yet on frequency). There are no obvious 
problems with the raw data and using FSL's FDT to do a simple least 
squares log signal fit doesn't produce this error. Looking at the error 
codes there are some 6's (bad data), but not corresponding to the 
problem voxels. I'd thought it might be a convergence problem, but we 
don't seem to be getting any error code = 2.

Does anyone have any suggestions for things we could try to solve this 
problem? The Camino version is a fairly recent release (r1014).

Thanks for your time,
Ian