Getting qfac set to 1 but header file does not change.

[hbhutta]

I have a lung CT image that I am viewing in ITK snap. When I check the image information there it shows that pixdim[0] (qfac) is 0. When I save the image and then open it up again in ITK snap, the qfac is still 0. How can I make sure that the qfac is changed to 1?