The Algorithmic Role of Critical Radiographic Features in the Treatment of Angioinvasive Fungal Sinusitis

Angioinvasive fungal sinusitis (AIFS) is a rapidly progressive, highly morbid infection. It can be challenging to obtain an early diagnosis, but intervention in the acute period is crucial for prognosis. Previous literature has identified numerous radiographic features with high sensitivity and specificity for AIFS, even in early disease. Bedside nasal endoscopy can substantiate the diagnosis but can also yield false negative results. Initially, these patients may present to the ophthalmologist. Thus, to avoid visual and potentially life-threatening complications, subtle clinical signs in conjunction with suspicious radiographic features must be promptly recognized by the ophthalmologist and escalated appropriately. We review, for the benefit of the ophthalmic community, the salient radiographic features of AIFS and integrate them into a decision-making algorithm for diagnostic workup and management.

A literature search was conducted using a comprehensive keyword search in the Pubmed and Embase databases. English studies from 1988 to 2022 describing the radiographic features of AIFS queried. Literature on the newly described entity, COVID-19 COVID-19-associated mucormycosis was included. The authors collected the most frequently reported indicators of AIFS.

The authors review 4 radiographic findings that are frequently associated with AIFS, including in the early stages of disease: 1) loss of contrast enhancement in the nasal turbinate and maxilla (i.e., "black turbinate and maxillary sign"), (2) periantral involvement seen as changes in density, fat stranding or obliteration of the anterior, retromaxillary, or retroantral fat planes on CT, (3) Tissue invasion without bony erosion, (4) Hypointense T2W sinonasal secretions on MRI in the setting of acute sinusitis. The authors additionally propose an algorithm that suggests surgical exploration for patients with clinical concern for AIFS and these radiographic features, even if bedside nasal endoscopy is inconsistent with AIFS.

The radiographic signs highlighted herein should heighten suspicion for AIFS in the appropriate clinical setting, prompting urgent surgical exploration regardless of nasal endoscopy findings.