Intraspinal tumours

Myelography can detect intraspinal tumours, but only the margins are visualised. Contrast enhanced MRI is able to visualise all spinal content directly; not only the borders of a tumour, but the whole lesion. MRI can differentiate cystic from solid tumours. CT can also detect intraspinal tumours, especially those localised outside the dural sac. But the sensitivity is fairly low due to small differences in X-ray absorption between normal and pathological tissue.

Therefore MRI is, practically speaking, the only modality which can characterise intra-spinal disorders.

Ordinary X-ray examinations are not able to reliably rule out intraspinal disease.

Extraspinal tumours - Tumours/destruction in vertebrae
Metastases from different primary tumours frequently affect the vertebrae. To be able to detect them, they either have to destruct parts of the vertebrae (osteolytic metastasis), or induce new bone formation (osteoblastic metastasis).

X-ray has a fairly good sensitivity to detect osteoblastic metastases but there can be problems to distinguish these from benign lesions. On the other hand osteolytic lesions need to be of some size to be detectable.

CT is useful to detect smaller destructions, and can also give useful information about soft tissue involvement.

Nuclear scans can detect osteoblastic lesions at a very early stage, but it can be a problem to differentiate these from degenerative changes. Osteolytic metastases are, on the other hand, hard to detect due to lack of osteoblastic involvement (which is needed for the radioactive markers to be taken up).