Hello,

I wouldn't mind jumping on this issue more broadly. Diffusion indices like FA, ADC, RD, and AD have more clear physiologic correlates. But what does the length of a tract, the volume of a tract, or the number of streamlines say about physiology? Tract length seems to be very dependent on head size. Or, for example, a person with a long corticospinal tract might simply be taller. At the very least these indices should be included with nuisance variables controlling for brain size. Length and volume measures seem to be very much affected by pulse sequence parameters, further calling into question their utility (see Wang et al., 2012; doi:
10.1016/j.neuroimage.2011.12.062). However, tract volume at least makes more intuitive sense (for example, quantifying Wallerian degeneration in T1 scans is essentially a volume measure). I thought Alan raised an important issue.

Anthony

Hi Imagers -

I am looking at the Uncinate fasciculus in a Cannabis use disorder (CUD). I found that CUD subjects have significantly shorter tract length  and a significant group x side interaction in comparison with controls. Have you seen this before? What is the interpretation of this finding?

Thank you,

Alan

_______________________________________________
Freesurfer mailing list
Freesurfer@nmr.mgh.harvard.edu
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer


The information in this e-mail is intended only for the person to whom it is
addressed. If you believe this e-mail was sent to you in error and the e-mail
contains patient information, please contact the Partners Compliance HelpLine at
http://www.partners.org/complianceline . If the e-mail was sent to you in error
but does not contain patient information, please contact the sender and properly
dispose of the e-mail.

-- 
Anthony Steven Dick, Ph.D.  
Assistant Professor
Director, Cognitive Neuroscience Program and Graduate Certificate in Cognitive Neuroscience  
Department of Psychology  
Florida International University Modesto A. Maidique Campus AHC4 454  
11200 S.W. 8th Street  
Miami, FL 33199  
Ph: 305-348-4202; Lab Ph: 305-348-9055; Fx: 305-348-3879  
Email: adick@fiu.edu
Webpage: http://myweb.fiu.edu/adick
Join the Society for the Study of Human Development: http://www.sshdonline.org