Hi Joon,

it depends on your field strength, receive coil and amount of acceleration. For example, at 3t with a 12 channel and 2x acceleration 1 acquisition is probably better than two as the blurring from motion correction hurts the CNR more than the noise reduction helps it. At 1.5T with a single channel the reverse is true, and you are better off with 2 or more acqs.

cheers Bruce

On Wed, 8 Dec 2010, Joonkoo Park wrote:

Dear freesurfers,

I believe it is recommended to have two high-resolution images for one subject (same acquisition parameters) for recon-all (i.e. 001.mgz and 002.mgz in /mri/orig). I'm sure recon works, however, with just one image (001.mgz). What is the relative advantage of having two images? Will having two images give me "substantial" improvement in parcellation and segmentation qualities? I am trying to gauge how important it is to have two scans of high-res images.

Thank you!

Joon

-- Joonkoo Park Ph.D. Candidate, Cognition & Cognitive Neuroscience Department of Psychology, University of Michigan http://www.joonkoo.org/