Diagnostic imaging of the nose and paranasal sinuses.

There are four principal modalities now used by the Radiologist to investigate the nose and paranasal sinuses. These are: plain X-ray, conventional tomography, computerised tomography (CT), and magnetic resonance (MR). Plain X-ray is the initial examination, and is used as a screening procedure before employing one of the tomographic techniques. Conventional pluridirectional tomography has now been superseded by CT scanning, which has the advantage of providing both good bone detail and soft tissue imaging. Since the introduction of magnetic resonance (MR), this technique has replaced CT as the optimum method of showing the extent of soft tissue tumour in the sinuses. The introduction of the paramagnetic contrast agent Gadolinium (Gd DTPA) has improved its accuracy. In the anterior fossa discrimination between cerebral oedema and tumour invasion is better shown, and in the sinuses tumour is more easily identified from retained secretion and inflamed mucosa. The best method currently available to show pathology in the nose and sinuses is a combination of GdMR and CT: the former to identify the soft tissues and the latter to show bone changes.