The Role of Computed Tomography

CT shows the bony anatomy very well; this provides a map for endoscopic sinus surgery. However, the mu-cosal changes that it can show rarely tell us about the pathology in the sinuses (Goldwyn et al., 1995; Cousin et al., 2000).

Fig. 7.1a-c The plain radiograph (a) does not show that the frontal sinus that is diseased drains into the left frontonasal in-fundibulum, as is shown on CT (b and c).

Fig. 7.1a-c The plain radiograph (a) does not show that the frontal sinus that is diseased drains into the left frontonasal in-fundibulum, as is shown on CT (b and c).

Fig. 7.2 a, b Residual disease after maximum medical treatment. Then CT shows more detail of the extent of sinus disease.

It is easy to fill out a CT request form, but this may be a mistake—although CT has good sensitivity for diagnosing paranasal sinus disease, it has poor specificity; for example, there are many false-positive changes. Before you request a CT scan, think why you are doing it and what information it will provide. Without a clinical picture based on the history, examination, and a trial of medical treatment, it is impossible to give any specific meaning to a finding of "mucosal changes" on a CT scan (Jianetto and Pratt, 1995).

Unfortunately, one in three asymptomatic people have an abnormal CT scan, which makes CT a poor diagnostic tool for rhinosinusitis. It is, therefore, important not to request a CT scan in the initial management of patients unless there are specific reasons to do so. These include:

• Suspected intracranial or intraorbital involvement as a complication of rhinosinusitis

• Suspected atypical infection or malignancy

• Specific pathology, e.g., mucoceles, benign tumors of the paranasal sinuses, where the extent of the lesion needs to be defined

• Prior to orbital or optic nerve decompression

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Post a comment