Imaging Features of COVID-19-Associated Acute Invasive Fungal Rhinosinusitis

Abstract Background  Acute invasive fungal rhinosinusitis (AIFR) is a rare, rapidly progressive, and life-threatening infection involving the nasal cavity and paranasal sinuses. Purpose of this study is to describe imaging features of coronavirus disease-2019 (COVID-19)-associated AIFR. Methods  This was a retrospective observational study. Inclusion criteria: (1) post-COVID-19 patients with fungal rhinosinusitis detected on potassium hydroxide smear or histopathology; (2) onset of symptoms (facial pain, dental pain, facial swelling or discoloration, nasal bleed, periorbital swelling, ptosis, redness of eyes, vision loss) less than 4 weeks; and (3) magnetic resonance imaging/computed tomography (MRI/CT) done within 5 days before surgery. Exclusion criteria: (1) cases of sinusitis without a history of previous COVID-19 infection; and (2) cases in whom fungal hyphae were not demonstrated on pathological examination. Noncontrast CT and dedicated MRI sequences were done initially. Site of involvement, unilateral/bilateral involvement, pattern of mucosal thickening, enhancement pattern, periantral invasion, orbital invasion, intracranial involvement, perineural spread, vascular involvement, and bony involvement were recorded. CT and MRI imaging features were compared. Results  Analysis of 90 studies (CT and MRI) in 60 patients was done. Most common site of involvement was ethmoid followed by maxillary sinus. Bilateral disease was more common. Mucosal thickening with T2 hypointense septations was seen in 88.4% MRI studies. Periantral and orbital involvement was seen, respectively, in 84.6% and 55.7% cases of MRI. Intracranial involvement was noted in form of meningitis, cerebritis, abscess, infarct, hemorrhage, cavernous sinus, or perineural invasion. Vascular involvement was noted in form of vascular occlusion ( n  = 3), vascular narrowing ( n  = 3), and pseudoaneurysm ( n  = 2). MRI was more sensitive in detecting periantral invasion, deep infratemporal fossa, cavernous sinus involvement, perineural invasion, optic nerve involvement, and vascular occlusion and narrowing, while CT was superior in identification of bony erosions. Conclusion  Early recognition of AIFR in post-COVID-19 patients is important to prevent disease-related morbidity/mortality. Several rarely described findings are noted in our series of AIFR, like optic nerve involvement, pituitary fungal abscess, perineural spread, fungal aneurysms, and arteritis-related posterior circulation infarcts. MRI is superior for early detection of disease and in estimation of extent of disease, compared with CT. Imaging can help in early detection of AIFR, which has a significant impact on patient outcome.