Kern et al CT scanning clearly defines the surgical anatomy and the extent of the disease process (Meltzer et al 2004) (Figures 1 and 2). Mucosal thickening, bony changes, or air-fluid levels seen on CT are consistent with CRS (Benninger et al 2003). There are instances when lateral or axial imaging is required to determine the extent of the disease process. Magnetic resonance imaging (MRI) is not recommended for diagnosis of CRS due to its lack of specificity (Benninger et al 2003), however, it is superior to CT for differentiation between infectious (bacterial or viral) inflammation and fungal concretions as well as in detecting malignancies (Meltzer et al 2004). MRI can also detect extension of disease beyond paranasal sinuses into the orbital region and intracranial compartment (Benninger et al 2003). Laboratory tests, such as nasal cytology, nasal biopsy, and hematologic analyses are not necessary for the clinical diagnosis of CRS. They can aid in determining whether other conditions are present, such as acute bacterial infection or allergy, or more serious conditions such as cystic fibrosis, ciliary dysfunction, or various immunodeficiencies (Slavin et al 2005). Treatment There are no definitive guidelines for the treatment of CRS largely due to the lack of consensus on the etiology of the disease (Benninger et al 2003). CRS has commonly been treated with courses of oral antibiotics, but lack of clinical evidence for their efficacy in CRS makes this therapy controversial unless the patient is suffering from a superimposed acute bacterial inflammation upon the underlying chronic inflammatory condition (Slavin et al 2005). Unnecessary use of antibiotics in CRS may also Figure 1 CT scan of normal sinuses (Tichenor 2006). Note: +, border of maxillary sinus; *, maxillary sinus ostium; C, concha bullosa; CT, computed tomography; E, ethmoid sinuses; IT, inferior turbinate; MT, middle turbinate; S, septum; U, uncinate process. 322 Therapeutics and Clinical Risk Management 2007:3(2)