A multicentric observational study of imaging findings in COVID-19-related rhino-orbito-cerebral mucormycosis: a new Pandora’s box

Abstract

Background There is a sudden rise of fungal infection with corona virus disease. This is attributed to the immunomodulation by the disease and the drugs used, diabetes mellitus, steroid use, oxygen inhalation using dirty water, use of zinc and iron supplements, etc. Early diagnosis and prompt medical and surgical intervention is the mainstay of treatment. This can greatly reduce the high morbidity and mortality associated with this disease. The objective of the study is to describe the imaging findings of acute invasive rhino-orbito-cerebral mucormycosis (ROCM) in 25 patients with severe acute respiratory syndrome corona virus 2, from three different centers with proven mucormycosis. Special emphasis is placed on the signal enhancement patterns of sinonasal mucosa, the earliest and most common findings. Statistical analysis was performed using descriptive statistics. Results Computed tomography (CT) and magnetic resonance imaging (MRI) of 25 patients showed most commonly involved sinuses as maxillary and ethmoid sinuses (19, 76%) together. Sino-nasal mucosal thickening was the most common finding (24, 96%). Periantral infiltration (18, 72%) preceded before orbital (15, 60%), cerebral (5, 20%) and vascular (2, 8%) complications, with grossly intact bones. Sinus wall erosions were seen in only 2 patients (8%). Palatal (22%) and maxillary alveolar arch erosion (39%) were frequent findings. CT showed minimally enhancing hypodense soft tissue thickening as the predominant finding in involved areas, while MRI showed T1 and T2 iso- to hypointense mucosal thickening (62%) and intense (43%) and no (33%) contrast enhancement as the main finding. Conclusions Contrast enhanced MRI is better at demonstrating early mucosal abnormalities, turbinate necrosis, non-enhancing devitalized tissues, orbital apex involvement and intra-cerebral extension. Imaging findings of inflammatory tissue infiltration adjacent to the paranasal sinuses in premaxillary, retroantral fat, facial muscles, pterygopalatine fossa, temporal, infratemporal fossa and extraconal orbital fat along with typical patterns of sinonasal mucosal enhancement should raise the suspicion of acute invasive fungal etiology given the short duration of history and immunocompromised status. High incidence of periantral and orbital extension of the disease is suggestive of acute invasive form of fungal infection. Also the rapidly progressive inflammatory changes without much bone involvement should suggest the suspicion of ROCM. Bony, cerebral and vascular involvements are relatively late complications.

MRI as a road map for surgical intervention of acute invasive fungal sinusitis in Covid‐19 era

“…4,8,9 Main MRI findings mentioned in literature in consistent with AIFS were LOCE and extrasinus invasion. 4,9,10 Many descriptive radiological studies in AIFS compare CT and MRI findings either in or before Covid-19 era. They concluded that contrast MRI study is better tool at demonstrating extrasinus, orbital, intracranial extensions in comparison to minimal CT findings.…”

“…They concluded that contrast MRI study is better tool at demonstrating extrasinus, orbital, intracranial extensions in comparison to minimal CT findings. Moreover, both LOCE and extrasinus invasion had similar high specificity and sensitivity, LOCE showed wide observation range between two blinded observers 4,9 . Subsequently, many radiologists rely on extrasinus involvement rather than LOCE only.…”

“…Bony erosion sign is the most suspicious criteria of AIFS in CT scan but occurs relatively late in disease process and leads to historical high mortality rate up to 80%. MRI scan had changed diagnostic strategy of AIFS because of their ability to detect soft tissue and early perisunis involvement 4,8,9 …”

“…Any refractory sinus manifestation with orbital complications (visual defect, proptosis and ophthalmoplegia) should be investigated for possibility of AFIS especially in high risk patients by nasal endoscopy, radiology and biopsy 4 …”

“…Early diagnosis and management are the key consideration to minimise mortality rate. Mortality rate discrepancy in between studies may be due to different variables as reversibility of immunocompromised state, virulence of fungi, stage of invasive fungal infection, compliance with antifungal medications and surgical debridement (when to interfere, debridement efficacy) 4,5 …”