In which clinical situations is computed tomography (CT) scan superior to MRI and vice versa?
Radiographs should be obtained before a CT scan or MRI when evaluating musculoskeletal disorders. Radiographs depict subtle calcifications and collections of gas that may be very difficult to detect with MRI alone. CT scan is useful mainly to detect bony abnormalities but causes high radiation exposure. It is used occasionally when MRI is contraindicated (e.g., pacemaker). MRI utilizes nonionizing radiation and can demonstrate subtle soft tissue and bony changes before they become radiographically apparent.
- • CT scan indications:
- Acute trauma (complex fractures)
- Tarsal coalition
- Intraarticular osteocartilaginous loose bodies
- • MRI scan indications:
| Cervical spine disease or instability | Osteomyelitis |
| Spinal stenosis or disc disease | Soft tissue tumors or skeletal muscle pathology |
| Internal derangement of knee | PVNS |
| Rotator cuff tears and tendinosis | Inflammatory sacroiliitis |
| Avascular necrosis | Synovitis and tenosynovitis |
