Hi Folks

I use mri_convert to create nifti files from the dicom images from a 3T GE scanner.

One of the option for mri_convert is "-zgez" with the following description from the mri_convert help:

" -zgez, --zero_ge_z_offset set c_s=0 (appropriate for dicom files from GE machines with isocenter scanning)"

Before the scan we "landmark" the subject; that is we set a point on the head coil to "0" and then proceed with the scan. Pardon the naive question, but does "isocenter scanning" refer to this step ?

Also I created two nifti files with and without this flag; the only differences in the two headers were with in quartern_z field.

without flag quartern_z = -50.061 and with the flag quartern_z = -90. (and one entry each in srow_z, sform, qform and vox2ras were also affected)

Our scan has 180 slices and to me quartern_z = -90 seems the right one. is this correct ? Thanks Mehul