The CT scan and subtraction angiography in chemodectomas.

The value of subtraction angiography and CT scanning in the diagnosis of chemodectomas are illustrated by two cases, a glomus jugulare tumour which exhibited true malignant behaviour, and a carotid body tumour. The characteristic early arterial blush of a chemodectoma, which can be obscured by bone, is clearly seen following subtraction techniques revealing tumours as small as 0.5 cm. The chemodectoma appeared as an isodense tumour on the CT scan with uniform contrast enhancement and well-defined margins. The appearances, however, are not diagnostic of a chemodectoma and may be simulated by other tumours.