Henes FO, et al. – The accuracy of magnetic resonance imaging (MRI) based grading was compared with laryngoscopy–based subglottic stenosis (SGS) grading with pulmonary function tests (PFT) in patients with granulomatosis with polyangiitis (GPA). Outcomes showed that MRI and laryngoscopy offered comparable results for grading of SGS in GPA and correlated well with PFT. However, MRI was an attractive non–invasive and radiation free alternative for monitoring the severity of SGS in patients with GPA.

Methods

The ohysicians conducted 118 examinations of 44 patients with GPA and suspected SGS.
• All patients underwent MRI, laryngoscopy, and PFT.
• Stenosis was graded on a 4–point scale by endoscopy and MRI using the Meyer–Cotton (MC)–Score (score1: ≤50%; 2: 51–70%; 3: 71–99%; 4: 100%) and as percentage by MRI.
• Outcomes were compared with peak expiratory flow (PEF) and maximum inspiratory flow (MIF) from PFT, serving as objective functional reference.

Results

• In MRI, 112/118 examinations (95%) were rated positive for SGS (n=82: grade1; n=26: grade2; n=4: grade3) whereas in laryngoscopy 105/118 examinations (89%) were rated positive for SGS (n=73: grade1; n=24: grade2; n=8: grade3).
• MRI and laryngoscopy agreed in 75 of 118 examinations (64%).
• MRI determined higher scores in 20 (17%) and lower scores in 23 (19%) examinations compared to laryngoscopy.
• MC–scores as determined by both MRI and laryngoscopy showed comparable correlations with PEF (r=–0.363, p=0.016 and r=–0.376, p=0.012, respectively) and MIF (r=–0.340, p=0.024 and r=–0.320, p=0.034, respectively).
• Highest correlation was found between MRI–based stenosis grading in percentage with PEF (r=–0.441, p=0.003) and MIF (r=–0.413, p=0.005).