On 13 Nov 2002, the AFNI package was upgraded to read the Siemens DICOM mosaic format directly. If you upgrade to the latest release, you should be able to read such images using a command like
to3d -time:zt 17 121 0s alt+z fred*.ima
In this example, I've pretended that you have 17 slices, 121 repetitions, and made up some absurd name for your files.
Information about changes to AFNI are posted on the "Latest News" page, which you should peruse from time to time.
bob cox