autoimune disorder with neuro/cns involvement

Is it possible for a cat with contrast dye to reveal areas that would show disease that would not show up in regular mri. my brother and i are battling an unknown at this time disease that begins with infections that are hypersensative and lead to neuro / cns involvement. i have had 3 mri done in last 10 years that come back clean. my brother had a ct scan with dye that showed skull revealing "bone that appears moth-eaten". would this have shown up reg mris, or should i too request ct scan with dye (I have never had one with or without).