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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. Conclusions : 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.

Objectives: To set age-specific normal reference values for brainstem, cerebellar vermis, and peduncles measurements and characterize values’ variations according to gender, age, and age by gender interaction. Methods: 565 normal brain magnetic resonance examinations with normal anatomy and signal intensity of the supra and infratentorial structures were categorized into six age groups (infant, child, adolescent, young adult, middle-age adult, and old aged adults). Patients with congenital malformations, gross pathology of the supra or infratentorial brain, brain volume loss, developmental delay, metabolic disorders, and neuropsychological disorders (n = 2.839) were excluded. On midsagittal T1-weighted and axial T2-weighted images specific linear diameters and ratios of the brainstem, cerebellar vermis, and peduncles were attained. Two observers assessed a random sample of 100 subjects to evaluate the inter- and intra observer reproducibility. Intraclass correlation coefficients (ICCs), means ± standard deviation (SD), one, and two-way analysis of variance tests were used in the statistical analysis. Results: Good to excellent inter- and intra observer measurements’ reproducibility were observed, except for the transverse diameter of the midbrain, the anteroposterior diameter of the medulla oblongata at the pontomedullary and cervicomedullary junctions, cerebellar vermis anteroposterior diameter, and thickness of the superior cerebellar peduncle. Age-specific mean values of the investigated measurements were established. A significant gender-related variation was recorded in the anteroposterior diameter of the basis pontis (p = 0.044), the anteroposterior diameter of the medulla oblongata at the cervicomedullary junction (p = 0.044), and cerebellar vermis height (p = 0.018). A significant age-related change was detected in all measurements except the tectal ratio. Age by gender interaction had a statistically significant effect on the tectal ratio, inferior, and middle cerebellar peduncles’ thickness (p = 0.001, 0.022, 0.028, respectively). Conclusion: This study provides age-specific normal mean values for various linear dimensions and ratios of the posterior fossa structures with documentation of measurements’ variability according to gender, age, and their interaction. Advances in knowledge: It provides a valuable reference in the clinical practice for easier differentiation between physiological and pathological conditions of the posterior fossa structures especially various neurodegenerative diseases and congenital anomalies.

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