 |
 |
Dear Tetsuya: My suggestion is to check your normalized images. If your normalization is not good, definitely you will not get good segmentation. Did you set the anterior commisure (AC) as the origin before your normalization, which might help! Yong Zhang Radiological Sciences Department St. Jude children's Research Hospital On 10/19/05, Darren Gitelman <[log in to unmask]> wrote: > > [log in to unmask] > > I second the comments by Marco and Philipp. If > you are using the standard brain templates from > SPM these may not properly reflect the degree of > atrophy for elderly brains and contrast of your > images. I also wonder about the gray/white/csf > contrast in your images. Also a slight bit of > movement in the 4 subjects that failed to segment > properly might have been caused by enough added > enough noise to reduce image contrast. > > Darren > > At 11:15 PM 10/18/2005, Iidaka wrote: > >Dear expert. > > > >I am getting into trouble with optimized VBM and T1 images of elderly > >subjects. When hi-resoution (1.7 x 0.82 x 0.82mm voxel) images were > >segmented, gray and csf are not properly segmented. Seg1 image appears to > >include both grey and csf, and seg3 image has only outer brain tisssues. > >Please see an attached jpeg image. Among 11 brains processed, the miss- > >segmentation occured in four images. These four T1 images do not look > very > >difefrent from other properly segmented images. > > > >Any help is very much appreciated. > > > >Tetsuya Iidaka > >Department of Psychiatry > >Nagoya University > > > > > > > ------------------------------------------------------------------------- > Darren R. Gitelman, M.D. > Cognitive Neurology and Alzheimer¹s Disease Center > Northwestern Univ., 320 E. Superior St., Searle 11-470, Chicago, IL 60611 > Voice: (312) 908-9023 Fax: (312) 908-8789 > ------------------------------------------------------------------------- >