How reliable is a CT scan of the sinuses in a patient who does not respond to an initial extended course of antimicrobial treatment for sinusitis? — Lisa Gordon, PA-C, New Port Richey, Fla.

There is no need for imaging in a case of acute sinusitis. CT scanning is considered the imaging procedure of choice for subacute (lasting one to three months) or chronic (lasting longer than three months) sinusitis, especially if surgery is being considered. Inadequate drainage is believed to be the cause of sinusitis. Removal of the obstruction is the goal of surgical interventions.

Functional endoscopic sinus surgery (FESS) has revolutionized the treatment of sinusitis. CT scanning can provide excellent imaging of the anatomy and pathologic patterns of the sinuses prior to surgery. Plain radiography, taken with the patient standing erect, may show fluid levels in acute sinusitis; mucosal thickening and retention cysts may be seen in chronic sinusitis.

The superiority of CT scanning using cuts of 2-3 mm has severely limited the role of plain radiography in assessing sinus disease. However, up to 40% of asymptomatic adults will show abnormalities of their sinuses on CT; diagnosis should be made in conjunction with history, physical exam and endoscopic findings.

MRI is preferred in cases of complicated sinus disease because it provides excellent imaging of soft tissue but not of bone. MRI is indicated in patients with intracranial complications, an extension of infection or suspected superior sagittal venous thrombosis. — Claire Babcock O’Connell, MPH, PA-C (158-4)