welcome to Health care magic.
1.Every imaging modality / scans (
MRI, CT,
Ultrasound,X-ray) has there own limitation, some are seen good in MRI, some in CT and so on.
2.In your case you have a problem with spine - where MRI is recommended by any doctor, as disc pathology,
nerve pathology, chord will be better seen.
3.In your case, MRI identified the collection / mass - from where a sample has to be taken to identify the pathogens (Disease causing organs) which is done well with CT guidance.( and its looking like Tubercular disease to confirm it)
4.First one has to find the reason behind so CT ,once the cause is identified - then treatment can be started.
Hope it helps you. Wish you a good health.
Anything to ask ? do not hesitate. Thank you.