Preferred Imaging Modality for Chronic Rhinosinusitis
Multiplanar CT is the preferred imaging modality for patients with chronic rhinosinusitis due to its superior ability to visualize both bony anatomy and soft tissue details. 1
Rationale for CT as First-Line Imaging
Multiplanar CT offers several advantages that make it the optimal choice for chronic rhinosinusitis evaluation:
- Provides excellent anatomic bony detail of the paranasal sinuses 1
- Offers both bone detail and soft-tissue imaging capabilities 1
- Can be performed with low-dose protocols to reduce radiation exposure 1
- Allows for coronal, axial, and sagittal plane visualization 1
Limitations of Alternative Imaging Modalities
Plain Sinus Radiography
- Highly inaccurate in a high percentage of patients 1
- Low sensitivity (25-41%) for most sinus groups except maxillary sinuses (80%) 1
- Has been largely supplanted by CT when imaging is necessary 1
MRI
- Not considered first-line for routine sinus imaging 1
- Lacks adequate bone detail which is critical for surgical planning 1
- Longer imaging times compared to CT 1
- Inspissated secretions may appear dark on T2 sequences, potentially mimicking air 1
- May be useful as a complementary study when soft tissue complications are suspected 2
Sinus Ultrasonography
- Not mentioned in guidelines as a recommended imaging modality for chronic rhinosinusitis 1
- Not validated for comprehensive evaluation of paranasal sinuses
Cone Beam CT (CBCT)
- May be used in select cases but has limitations in assessing soft-tissue structures 1
- Limited in evaluation of complications of sinus disease 1
- May be utilized for assessment of sinus anatomy in uncomplicated cases 1
Clinical Applications and Considerations
CT scanning is particularly valuable in chronic rhinosinusitis for:
- Preoperative planning for endoscopic surgery 1
- Delineation of complex ethmoidal anatomy and ostiomeatal unit 1
- Identification of anatomical variations that may predispose to CRS 3
- Objective confirmation in cases of chronic rhinosinusitis 1
- Integration with computer navigation systems for image-guided surgery 1
Important Caveats
- CT findings should always be interpreted in conjunction with clinical and endoscopic findings 1
- Up to 3-40% of asymptomatic adults may have abnormalities on sinus CT scans 1
- Intravenous contrast is generally not needed for routine evaluation 1
- Chronic rhinosinusitis is defined by the presence of at least two cardinal symptoms for at least 12 consecutive weeks, plus objective evidence 4
- Consider point-of-care CT in patients who meet symptom criteria but have negative endoscopy 5
Anatomical Variations to Evaluate on CT
CT can identify important anatomical variations that may contribute to chronic rhinosinusitis:
- Concha bullosa (64% prevalence in CRS patients) 3
- Deviated nasal septum (61.3%) 3
- Agger nasi cells (49.3%) 3
- Haller cells (32%) 3
- Onodi cells (21.3%) - important to identify due to risk of injury to optic nerves or carotid arteries during surgery 1, 3
In conclusion, multiplanar CT represents the gold standard imaging modality for evaluation of chronic rhinosinusitis, offering superior anatomical detail while newer protocols help minimize radiation exposure.