Imaging Features of Invasive Fungal Rhinosinusitis: A Systematic Review

Fungal rhinosinusitis (FRS) includes non-invasive and invasive subtypes with the latter having significant morbidity and mortality. This systematic review aims to identify the imaging features most correlated with invasive fungal rhinosinusitis (IFRS) and present a checklist of these features to aid diagnosis. PubMed, Embase, CENTRAL, and Science Direct were searched from inception to May 2023, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Primary research articles published in English describing the imaging features of IFRS were included. The systematic review was conducted in accordance with the PRISMA guidelines. Forty-eight articles were identified for inclusion. Six studies examined radiological features in acute invasive fungal rhinosinusitis (AIFRS), and 9 studies of chronic invasive fungal rhinosinusitis (CIFRS). A majority of studies did not specify whether IFRS cases were acute or chronic. On CT, bony erosion and mucosal thickening were the most common features. Other features include nasal soft tissue thickening, nasal cavity opacification, opacification of the affected sinus, and perisinus soft tissue infiltration. Extra-sinus extension was commonly observed on MRI, most often invading intraorbitally and intracranially. Other sites of extra-sinus extension included the cavernous sinus, pterygopalatine fossa, infratemporal fossa, masticator space, and facial soft tissue. IFRS is a condition with potential for high morbidity and mortality. Several radiological features are highly suggestive of IFRS. Early identification of high-risk radiological features using a checklist may aid prompt diagnosis and early treatment. Future research investigating the radiological differentiation between IFRS and other significant pathology including bacterial orbital cellulitis would be beneficial.