Table 3.

Salient features of malignant skull lesions on CT and MRI

Skull Lesion	CT	MRI
Multiple myeloma (multiple)	Osteolytic lesions without sclerotic rim, “punched-out lesions”.	Hypointense T1, hyperintense T2. “Salt and pepper marrow infiltration” is the most common pattern. Typically enhance.
Osteosarcoma	Lytic lesion, ill defined borders. Aggressive periosteal reaction. Variable amount of osteold matrix.	Variable appearance.
Metastases (may be solitary or multiple)	Lytic, sclerotic or mixed depending on the primary tumour.	Hypo/isointense T1, hyperintense T2. Typically enhance (unless sclerotic).
Chordoma (skull base, midline)	Lytic destructive expansile lesion of the clivus.	Hypointense T1, lobules of high signal on T2. Heterogeneous enhancement.
Chondrosarcoma (skull base, paramidline)	Osteolvtic lesion. Chondroid matrix with “rings and arcs”.	Hypo/isointense T1, hyperintense T2. “Whorls of enhancement”.