What is the role of computed tomography (CT) of the paranasal sinuses in evaluating patients with chronic allergic rhinitis?

From the Guidelines

Computed tomography (CT) of the paranasal sinuses is a crucial diagnostic tool in evaluating patients with chronic allergic rhinitis, particularly when symptoms persist despite appropriate medical therapy or when complications are suspected, as it provides detailed visualization of the sinus anatomy and helps identify complications that may influence management decisions.

Key Points to Consider

• CT scans are preferred over plain radiography due to their superior ability to delineate soft tissue and bony structures, as noted in the study by 1.
• The use of CT imaging should be considered after failure of standard treatments, including intranasal corticosteroids, antihistamines, and possibly leukotriene modifiers, as these treatments are often the first line of defense against chronic allergic rhinitis.
• CT scans can help identify complications such as chronic sinusitis, nasal polyps, anatomical obstructions, or rare but serious conditions like fungal sinusitis or neoplasms, which can significantly impact morbidity, mortality, and quality of life.
• The imaging findings directly influence management decisions, potentially indicating the need for surgery, immunotherapy, or biological therapies like dupilumab for severe cases, as discussed in the study by 1.
• MRI may be considered as an alternative in specific cases where soft tissue detail is more important than bony anatomy, such as in suspected fungal sinusitis or differentiating between inflammatory disease and malignant tumors, as mentioned in the study by 1.

Important Considerations for CT Imaging

• CT imaging should be used judiciously to minimize radiation exposure, particularly in children and pregnant women, highlighting the need for careful consideration of the risks and benefits.
• The American College of Radiology has stated that plain films of the sinuses are inaccurate in a high percentage of patients and should be supplanted by CT imaging, as noted in the study by 1.
• CT imaging is the optimal technique for evaluating the ethmoid sinuses and for preoperative evaluation of the nose and paranasal sinuses, including assessment of the ostiomeatal complex areas, as discussed in the study by 1.

From the Research

Role of Computed Tomography (CT) in Evaluating Patients with Chronic Allergic Rhinitis

• Computed Tomography (CT) scans of the paranasal sinuses are used to evaluate the extent of disease in patients with chronic allergic rhinitis, but the correlation between CT stage and severity of symptoms is not always significant 2.
• CT scans can detect mucosal thickenings, bony changes, and anatomic variations in the paranasal sinuses, which can be useful in diagnosing chronic rhinosinusitis 3.
• Low-dose CT scans may be more effective than plain X-rays in detecting paranasal sinus abnormalities, particularly in the maxillary and frontal sinuses 4.
• The presence of maxillary mucosal thickening, frontal hypoplasia, or pneumatized uncinate process on CT scans may be indicative of allergic chronic rhinosinusitis 3.
• CT scans can also be used to evaluate the correlation between the opacification degree of paranasal sinuses and clinical symptoms, as well as anatomical variations of the nose and paranasal sinuses in patients with chronic rhinosinusitis 5.

Correlation between CT Findings and Clinical Symptoms

• There is a significant correlation between the opacification degree of paranasal sinuses on CT and certain clinical symptoms, such as purulent nasal drainage, nasal obstruction, and hyposmia/anosmia 5.
• The severity of symptoms in patients with chronic rhinosinusitis may be predicted by the CT scan score, particularly for symptoms such as nasal obstruction, hyposmia/anosmia, and fatigue 5.
• However, the correlation between CT findings and clinical symptoms is not always significant, and other factors such as allergic disease may play a more important role in determining symptom severity 2.

Comparison with Other Diagnostic Methods

• Low-dose CT scans may be more effective than plain X-rays in detecting paranasal sinus abnormalities, particularly in the maxillary and frontal sinuses 4.
• CT scans may be more sensitive than nasal endoscopy, rhinomanometry, or nasal swab in detecting sinusitis in patients with perennial allergic rhinitis 6.