What is the standard method for CT grading in chronic rhinosinusitis?

Standard CT Grading Method for Chronic Rhinosinusitis

The Lund-Mackay scoring system is the standard method for CT grading in chronic rhinosinusitis, based on the degree of opacification for the paranasal sinuses and ostiomeatal complex. 1

Lund-Mackay Scoring System Details

• The Lund-Mackay system scores each sinus based on the degree of opacification: 0 (none), 1 (partial), or 2 (complete) 1
• The following sinuses are evaluated bilaterally: maxillary, anterior ethmoids, posterior ethmoids, frontal, and sphenoid 1
• The ostiomeatal complex is scored as either 0 (not obstructed) or 2 (obstructed) 1
• The maximum total score is 24 points (12 points per side) 1
• This scoring system has been validated in multiple studies and is widely accepted as the standard method 1

Clinical Relevance of Lund-Mackay Scores

• A Lund-Mackay score of 2 or less has excellent negative predictive value 1
• A score of 5 or more has excellent positive predictive value, strongly indicating true disease 1
• In pediatric rhinosinusitis, a Lund-Mackay score of at least 5 provides 86% sensitivity and 85% specificity 1
• Using a cut-off value greater than 2 for CRS diagnosis yields 94% sensitivity and 41% specificity 1
• When using "normal" LMS scores (>4) as the threshold, specificity increases to 59% 1

Alternative Scoring Systems

• Alternative CT scoring systems have been proposed but have not shown significant improvement in correlation with symptom severity scores or health-related quality of life impairment 1
• Another scoring system described in clinical trials grades based on the degree of obstruction and amount of mucosal thickening:
  • Nasal passages and ostiomeatal complex: scored 0-3 points based on soft tissue obstruction 1
  • Paranasal sinuses: scored 0-3 points based on mucosal thickening measured in millimeters 1

Clinical Application Guidelines

• CT imaging is not normally recommended until after an appropriate course of medical therapy has failed 1
• The EPOS2020 steering group considers a total Lund-Mackay score of 0 as clinically irrelevant 1
• Scores of 2 due to complete obstruction of one sinus, or scores of 3 or greater (whether unilateral or bilateral) are considered clinically relevant 1
• The presence of complete opacification of any sinus is considered clinically positive 1
• For both medical and surgical treatment planning, a CT scan performed within the previous six months is considered acceptable 1

Correlation with Symptoms and Disease

• The only symptom that significantly correlates with CT scores is olfaction 1
• There is generally weak correlation between CT stage and patient-reported symptoms in CRS overall 1
• CT scores correlate significantly with the stage of inflammation in histopathological analysis of sinus mucosal samples, most notably in CRS without nasal polyps 1
• Recent studies show that preoperative Lund-Mackay scores in patients with medically recalcitrant CRS correlate with preoperative symptom severity and can indicate postsurgical quality of life outcomes 1

Important Considerations

• Low-dose CT protocols have significantly reduced radiation exposure while maintaining diagnostic accuracy 1
• The pattern of inflammation may have diagnostic value - a central radiological pattern of mucosal disease (the "black halo" sign) is associated with inhalant allergen sensitization 1
• Other radiologic features such as neo-osteogenesis may have prognostic implications and can be scored separately 1
• When evaluating CT scans, the degree of mucosal thickening, number of sinuses affected, and status of the ostiomeatal complex should all be considered, though their individual importance remains unclear 1