What is the best imaging modality to assess anatomical issues like a deviated septum?

Imaging Modalities for Assessing Deviated Nasal Septum

CT scan without contrast is the optimal imaging modality for assessing anatomical issues like a deviated septum, particularly when surgical intervention is being considered. 1

Primary Diagnostic Approach

Clinical Evaluation

• Initial assessment should be performed using:
  • Anterior rhinoscopy (using an otoscope in primary care settings)
  • Nasal endoscopy (gold standard for direct visualization)

Imaging Algorithm

1. First-line imaging when surgery is considered: CT Maxillofacial without contrast

   • Provides excellent bony detail and soft tissue visualization 1
   • Critical for surgical planning by identifying anatomic variants 1
   • Allows multiplanar and 3D reconstructions for better characterization 1
   • Can determine the degree of septal deviation 1

2. When to avoid CT for isolated septal deviation:

   • CT should not be performed solely for evaluation of septal deviation 1
   • Should be used when evaluating associated symptoms of chronic rhinosinusitis or for surgical planning 1

Advantages of CT for Deviated Septum Assessment

• Accurately identifies associated anatomical variants that may contribute to nasal obstruction:

  • Concha bullosa (pneumatized turbinates) 2
  • Inferior turbinate hypertrophy 3
  • Paradoxical middle turbinate 2
  • Ostiomeatal complex abnormalities 4

• Provides critical measurements:

  • Cross-sectional area at various points in the nasal cavity 5
  • Internal nasal valve angle 5
  • Deviation angle and volume 3

• Helps differentiate between anterior and posterior septal deviations, which have different clinical implications 5

Alternative Imaging Modalities

Ultrasound

• Not first-line but has shown high accuracy (90-100% sensitivity, 98-100% specificity) 1
• May better detect non-depressed fractures of the nasal bridge and anterior septal cartilage deviation than CT 1
• Limited in assessing deeper structures and overall nasal anatomy

MRI

• Not recommended as first-line for sinonasal imaging due to:
  • Lack of bony detail 1
  • Higher cost 1
  • Potential for overdiagnosis compared to CT 1

Plain Radiography

• Limited diagnostic value (53-82% accuracy) 1
• Does not significantly alter diagnosis or management 1
• Has been largely replaced by CT due to superior anatomic detail 1

Clinical Impact of CT Imaging Before Septoplasty

• Identifies additional pathologies not evident on physical examination in a significant percentage of patients 2
• Allows for planning of concurrent procedures (turbinate reduction, sinus surgery) 2
• Results in improved patient outcomes and higher satisfaction with nasal airflow 2
• Helps determine the optimal surgical approach based on the specific anatomical abnormalities 6

Important Caveats

• CT findings of septal deviation may underestimate the degree of nasal obstruction at the internal nasal valve 1
• Clinical correlation is essential as CT findings don't always correlate with symptom severity 1
• Low-dose CT techniques should be employed when possible to minimize radiation exposure 1
• For patients with suspected deviated septum and obstructive sleep apnea, CT findings can support the need for surgical intervention 6

CT maxillofacial without contrast remains the imaging modality of choice when surgical intervention is being considered for a deviated septum, providing comprehensive anatomical detail that guides surgical planning and improves outcomes.