Pitfalls in computed tomography of the paranasal sinuses

The advent of functional endoscopic sinus surgery has created the need for high-quality radiographic images to assess the paranasal sinuses, document the detailed anatomy of the lateral nasal wall and provide an anatomical map allowing safe functional endoscopic sinus surgery. This paper will discuss our experience of 410 paranasal sinus coronal CT scans performed by the technique described by Zinreich prior to consideration of functional endoscopic sinus surgery. The main indications for the scans were acute recurrent sinusitis, abnormal diagnostic nasal endoscopic examination and persistent facial pain. We will consider both the radiological and surgical difficulties that have arisen from the use of this technique and highlight some of the methods to avoid these difficulties. Claustrophobia and limitation of neck movements, particularly in patients over the age of 60, were the most common factors leading to suboptimal scans. Ensuring that the patient was in a symptom-free interval, the differential diagnosis of the opacified paranasal sinus and patients with gross polypoid disease created the most difficulty in interpretation. The anatomical assessment of the frontal recess and the identification of the optic nerve posterolateral to the posterior ethmoidal cell have created the greatest anatomical difficulty.