[MINC-development] MI_ICV_DO_DIM_CONV and slice dimension

[Rick Hoge]

I've been working with the minc ICV functions, and have noticed what to 
me seemed counterintuitive behaviour associated with the 
MI_ICV_DO_DIM_CONV parameter.  My understanding from the documentation 
is that a value of TRUE should flip any dimensions that have a negative 
step size.  However I have noticed that while in-plane dimensions are 
flipped to put the posterior-left corner of a transverse slice at the 
beginning of the buffer, slices are not flipped.  Is this consistent 
with what other people have seen or expect?  Maybe I am 
misunderstanding the docs but I'd expect the forced consistency with 
positive step sizes to be all-or-none.

For us a typical case would be a transverse EPI scan from one of our 
Siemens Numaris 4 systems with negative steps in all of x, y, and z 
(pixeldata buffer starts at front right corner of top slice), all dims 
need to be flipped to achieve positive step sizes.

This may explain some other confusing behaviour we've seen in the past, 
and I'd appreciate it if anyone could confirm how this is supposed to 
work.

Rick

______________________________________
Richard D. Hoge, Ph.D.
Instructor, HMS Department of Radiology
A. A. Martinos Center for Biomedical Imaging
149 13th St.
Charlestown MA 02129
phone 617-726-6598
fax    617-726-7422
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