MRI Evaluation of Invasive Sinonasal Mucormycosis in Post COVID-19 Patients: A Retrospective Study

Introduction: Mucormycosis is also known as phycomycosis or zygomycosis, is caused by a saprophytic fungal infection. During the second wave of coronavirus disease-2019 (COVID- 19), secondary complication among clinically severe COVID-19 with or without diabetes was the involvement of the paranasal sinuses, rhino-orbitalocerebral, cutaneous, gastric and lungs by mucormycosis. The disease progresses rapidly within a few hours to days, causing cranial nerve palsies and intracranial spread of the disease. Early imaging is helpful in assessing the extent of the spread of the disease and complications and planning the treatment. Aim: The purpose of this study is to assess the distinct MRI findings in invasive sinonasal mucormycosis in post COVID-19 patients and also to describe the various patterns of extension. Materials and Methods: This retrospective study was carried out on post COVID patients with imaging features of invasive sinonasal mucormycosis in the rural population of Hoskote, Bangalore, who underwent MRI at MVJ Medical College and Research Hospital, Hoskote, Bangalore, India in a tertiary care center, between May 2021 to July 2021. A total of 20 patients met the inclusion criteria. The various imaging features of invasive sinonasal mucormycosis were evaluated and tabulated, along with a description of its extensions. All the data obtained from the study was compiled with Microsoft Excel (2019 version). Results: The study showed a male predominance with a mean age of 47.5 years. The most commonly involved sinus was the ethmoid sinus, seen in all 20 patients (100%), followed by a combination of the ethmoid and maxillary sinus 10 (50%). MRI showed T2W hyperintense mucosal thickening with hypointense contents within the involved sinuses in all cases, hypointensity along the turbinates and nasal septum and heterogeneous post contrast enhancement. The intraorbital extension was seen in 15 patients (75%), intracranial involvement in 4 patients (20%), bone involvement in 2 cases (10%) and pterygopalatine fossa involvement in 5 patients (25%), face involvement seen in 2 patients (10%). Conclusion: Magnetic Resonance Imaging (MRI) aids in a thorough evaluation of intracranial and soft tissue involvement, orbital, skull base invasion, perineural spread and vascular invasion. MRI demonstrates variable signal intensity depending on the sinus contents and variable enhancement patterns with a lack of enhancement due to tissue necrosis, an early finding of mucormycosis. Therefore, radiologists should be aware of the imaging findings and evaluation of the extensions, which can lead to early diagnosis and timely management, reducing the morbidity and mortality rates.