From the Guidelines
For evaluating chronic sinusitis, a non-contrast CT scan is the preferred imaging study, as it provides excellent detail of the sinus anatomy, ostiomeatal complex, and extent of disease without the need for contrast, as supported by the most recent guidelines 1. When evaluating chronic sinusitis, the primary goal is to assess the extent of disease, anatomic variations, and potential complications.
- The use of non-contrast CT scans is recommended for routine evaluation of chronic sinusitis, as it allows for the visualization of mucosal thickening, air-fluid levels, bony changes, and anatomic variations without the need for contrast 1.
- Contrast should only be added when there is concern for complications such as orbital or intracranial extension of infection, fungal sinusitis, or neoplasm, as it may aid in the evaluation of soft tissue extension and invasion into adjacent structures 1.
- The non-contrast study exposes the patient to less risk, including no IV contrast reactions or nephrotoxicity, while providing all the necessary information for diagnosis and surgical planning in most cases of chronic sinusitis.
- The scan should be performed in the coronal plane or with multiplanar reconstruction capabilities to best evaluate the ostiomeatal complex, which is often the site of obstruction in chronic sinusitis, as highlighted in the guidelines 1. Key considerations in the evaluation of chronic sinusitis include:
- The documentation of sinonasal inflammation, which may also be accomplished with anterior rhinoscopy or nasal endoscopy 1.
- The use of CT scanning to provide the best preoperative information for endoscopic surgery, with excellent delineation of the complex ethmoidal anatomy, ostiomeatal unit, and anatomic variations 1.
- The potential for image-based guidance surgery during endoscopic sinus surgery, which can reduce surgical risks by providing real-time information of instrument location relative to critical structures 1.
From the Research
Evaluation of Chronic Sinusitis
To evaluate chronic sinusitis, imaging studies such as CT scans are often used. The decision to order a CT scan with or without contrast depends on the clinical scenario.
CT Scan with or without Contrast
- For patients with uncomplicated chronic sinusitis, a CT scan without contrast is the imaging method of choice 2.
- The use of contrast is recommended in cases of complicated sinusitis, such as when there are intracranial or orbital complications 3.
- CT scans with contrast may also be used to evaluate sinus disease in cases of aggressive sinus infection, potential invasive fungal sinusitis, or in the evaluation of a sinonasal mass 2.
Alternative Imaging Modalities
- MRI may be used as a complementary study in cases of complicated sinusitis, but it is not typically used as a first-line imaging modality for uncomplicated chronic sinusitis 3, 2.
- Nasal endoscopy is a valid and objective diagnostic tool in the workup of patients with symptomatic chronic rhinosinusitis, and may be used to reduce the need for CT scans in selected patients 4.
Imaging Protocols
- The coronal plane is the best incidence for CT scans of the sinuses, as it most closely correlates with the surgical approach 3.
- A high-resolution bony algorithm is recommended, with a window of intermediate type (2500 with a center of 250 HU) sufficient for nearly all diagnoses 3.
- Complementary direct axial sections may be needed to guide the approach to the sphenoid sinus and posterior ethmoidal cells 3.