OK, this mail is actually from Matthew Brett, but it references code written by John.

Subject: Re: Scale factor
From: Matthew Brett 
Date: Tue, 22 May 2001 18:47:15 -0700 (21:47 EDT)
To: SPM@JISCMAIL.AC.UK

Dear Masahiro,

> I would like to incorporate scaling factors to many header files.
> It would be nice if I can incorporate multiple scaling factors saved
> in a text file into multiple header files.  Is there a way to do
> this? 

For the same problem, I have used an utility written
by John Ashburner many eons ago, called dbedit:

http://www.mrc-cbu.cam.ac.uk/Imaging/dbedit.html

You need to script it somehow, obviously, but the line in the file
setting your scale factor might look like:

    dbedit myfile.hdr dime.funused1=$myval

where your scale factor is in the variable $myval

I've also been playing with some perl functions to do this kind of
thing, written by Andrew Janke:

http://www.cmr.uq.edu.au/~rotor/software/

Best,

Matthew
  

dbedit tarball:dbedit.tar.gz