Post COVID-19 Head and Neck Mucormycosis: MR Imaging Spectrum and Staging

Abstract

Objective: To develop a systematic approach for magnetic resonance imaging (MRI) analysis, imaging spectrum, and classification system for the staging of post-COVID-19 head and neck mucormycosis.

Method: The study included 63 post-COVID-19 patients with pathologically proven mucormycosis who underwent head and neck MR imaging. Three independent radiologists assessed the imaging spectrum of mucormycosis, MRI characteristics of sino-nasal mucormycosis, and extra-sinus extension, and submitted a final staging using a systematic approach and a proposed categorization system. A consensus reading was considered the reference imaging standard. The kappa statistics were used to assess the categorization system's diagnostic reliability.

Results: The overall interreader agreement of the MR staging system was very good (k-score = 0.817). MR imaging spectrum involved localized sino-nasal mucormycosis (n = 7 patients, 11.1%), sino-nasal mucormycosis with maxillo-facial soft tissue extension (n = 28 patients, 44.5 %), sino-nasal mucormycosis with maxillo-facial bony extension (n = 7 patients, 11.1%), sino-naso-orbital mucormycosis (n = 13 patients, 20.6%), and sino-nasal mucormycosis with cranium or intracranial extension (n = 8 patients, 12.7%). Extra-sinus extension to the orbit and brain did not have significant association with involvement of the posterior ethmoid/sphenoid sinuses and maxillo-facial regions (p > 0.05). MRI-based staging involved four stages: stage 1 (n = 7, 11.1%); stage 2 (n = 35, 55.6%), and stage 3 (n = 13, 20.6%), and stage 4 (n = 8, 12.7%). Involvement of the bone and MR-based staging were significant predictors of patients' mortality p = 0.012 and 0.033, respectively.

Conclusion: This study used a diagnostic-reliable staging method to define the imaging spectrum of post-COVID-19 head and neck mucormycosis and identify risk variables for extra-sinus extension.

Keywords: COVID-19; Magnetic resonance imaging; Mucormycosis; risk factors.

Figure 1

Systematic approach for MRI analysis in head and neck mucormycosis.

Figure 2

A 63-year-old diabetic and hypertensive female patient who experienced left facial swelling, ptosis, and chemosis 3 weeks following COVID-19 infection, and received corticosteroid for 2 weeks. (A) and (B) axial T2W-SPIR images reveal complete opacification of the left maxillary sinus with homogeneous high signal intensity, and precisely demarcates the extension of the T2 high signal intensity anteriorly into the preantral region and zygomatic bone, and posteriorly into the left pterygopalatine fossa, retroantral fat, infratemporal fossa, left hemi-clivus, and cavernous sinus (arrows), (C) and (D) axial post-contrast T1W-fat-sat images showing “soap bubble sign” of the left maxillary sinus (arrows in C) with enhanced tissue at the left preantral, infratemporal, and cavernous sinus regions (arrows in D). Stage 4b (sinonasal mucormycosis with cranial extension).

Figure 3

A 53-year-old diabetic male patient presented with right facial palsy 1 month following COVID-19 infection, and received corticosteroid for 2 weeks (A) coronal T2W-TSE image reveals total opacification of the right maxillary and ethmoid air cells with high T2 signal intensity and hypointense septa, and destruction of the right superior alveolar margin and palate (white arrow), black arrow points to infiltration of infraorbital fat (B) axial T2W-SPIR demarcates the extension of infection into pterygopalatine and infratemporal fossa (arrow) (C) and (D) axial and coronal post contrast T1W-TSE images showing extension of infection into the right infratemporal fossa and palate, black arrow in D points to soap bubble appearance of the right maxillary sinus. Stage 3a (sinonasal mucormycosis with maxillo-facial soft tissue, bone extension, and intraorbital extraconal fat infiltration).

Figure 4

A 50-year-old diabetic and hypertensive female patient presented with left side ptosis, chemosis, limited left eye mobility, and confusion 14 days following COVID-19 infection, received corticosteroid for 12 days (A and B) axial T2W-SPIR reveal opacification of the both ethmoid air cells and sphenoid sinuses with heterogeneous T2 signal intensity, left intraconal soft tissue extension is noted (arrow in B) (C) axial FLAIR shows left inferior frontal cortical and subcortical high signal intensity compatible to area of facilitated diffusion on DWI at b-value 1000 (D). (E and F) axial and coronal post-contrast T1WI show non-enhancing ethmoid sinuses with enhanced intraconal soft tissue extension (black arrow in F). Stage 4c (rhino-cerebro-orbital mucormycosis).

Figure 5

A 70-year-old diabetic and hypertensive female patient presented with right eye swelling, chemosis and facial pain 21 days following COVID-19 infection, no history of corticosteroid usage. (A) and (B) axial T2W-SPIR image reveals complete opacification of the right ethmoid air cells with heterogeneous signal intensity, and right maxillary sinus with multiple hypointense septa on top of hyperintense signal, white arrow in (A) points to right intraorbital soft tissue extension white star in (B) points to necrotic right turbinate, (C) and (D) axial and coronal post-contrast T1W-TSE images showing soap bubble sign of right maxillary sinus, necrotic non-enhanced right turbinate “black turbinate sign” (white star in D), white arrow in (D) points to the intraorbital intraconal enhanced soft tissue. Stage 3b (sino-naso-orbital mucormycosis).

Figure 6

A 56-year-old hypertensive female patient presented with right eye swelling, ptosis, chemosis and facial pain 21 days following COVID-19 infection, received corticosteroid for 10 days. (A) coronal T2W-TSE image shows complete opacification of the right maxillary sinus and ethmoid air cells by heterogeneous signal with loss of the normal signal intensity of the right nasal turbinate, white arrow points to destructed lateral nasal wall (B) axial T2W-SPIR image reveals destructed right anterior maxillary wall marked by white arrow, thick black arrow points to abnormal high signal of the retroantral fat and infratemporal fossa (C) coronal post-contrast T1W-TSE image shows enhanced maxillary sinus mucosa with non-enhanced center, and right black turbinate sign (D) axial post contrast T1W- fat-sat image shows erosion of the anterior maxillary wall marked by arrows. Stage 2b (sino-nasal mucormycosis with maxillo-facial bone and soft tissue extension).