Lumbar disc disease
In symptomatic cases the diagnosis should be confirmed by an MRI scan. However, in cases with slight symptoms, a faster and cheaper CT scan (although it is inferior to MRI scan) may be recommended. While a CT scan can show the bony structures in more detail, an MRI scan can better portray soft tissue.
Soft tissue injury
Ultimately, the best method of imaging soft tissue is magnetic resonance imaging (MRI), though it is cost-prohibitive and carries a high false positive rate.