Multiple jpg mozaic to large single mr-SID

[giseis]

I have 90+ jpg imagery tiles(total 20GB in size ) extracted from single source MRSID(of 8GB in size).

Can I mozaic/merge it back to single MRSID (which must be only 7-10GB in size)?

I haven't used GEOexpress. Can GeoExpress do this job? Or is there exist any other tools?
Thank you

[giseis]

Please Help...