Feasibility of rapid magnetic resonance imaging (rMRI) for the emergency evaluation of suspected pediatric orbital cellulitis

Purpose: To determine the feasibility of noncontrast rapid magnetic resonance imaging (rMRI), compared with traditional contrast-enhanced computed tomography (CT) in assessing pediatric emergency department patients with suspected orbital cellulitis or orbital abscess. Methods: All subjects <19 years of age who presented emergently with suspected orbital cellulitis from July 1, 2017, to July 31, 2019, were included. Participants received both the standard contrast orbital CT, if deemed necessary, with the addition of the noncontrast rMRI after informed consent was obtained. No sedation was used for either examination. All clinical decisions were based on CT findings; rMRI was interpreted within 24 hours of the visit. Three pediatric radiologists, with 8-21 years’ experience of pediatric neuroradiology, interpreted the rMRI, masked to the CT and clinical results. Results were analyzed for interobserver bias. Results: A total of 14 patients were enrolled during the study period. Mean age was 5.9 years (range, 0.33-13). Of the 14 patients, 13 (93%) were able to complete the rMRI at 1.5 and 3T; 1 patient (1.67 years of age) was unable to complete the rMRI (no images obtained). Of the 26 unilateral orbital units assessed, 3 were positive for retroseptal orbital cellulitis by CT and were diagnosed correctly by rMRI. Interobserver agreement was 100% in detecting presence or absence of retroseptal cellulitis. CT and rMRI findings were concordant in 100% of cases in differentiating preseptal vs orbital cellulitis. Kappa statistics for three-category ratings by three raters for right eye/orbit was 0.921 and for left eye/orbit was 0.9288, suggesting almost perfect agreement. Concordance correlation coefficients were 0.938 for the right eye and 0.955 for the left eye. Conclusions: Noncontrast rMRI orbits showed findings concordant in all cases with contrast-enhanced CT for differentiating preseptal cellulitis from orbital cellulitis.