Infectious Aortitis on 18 F-FDG PET/CT.

ABSTRACT: Infectious aortitis is a challenging radiographic diagnosis due to overlapping features with the noninfectious category. We present a case of a 58-year-old woman who tested positive for SARS-CoV-2 and Streptococcus pneumoniae bacteremia. 18 F-FDG PET/CT demonstrated large vessel vasculitis involving the thoracic, abdominal aorta, and the brachiocephalic branches of the aortic arch, and an incidental subcutaneous abscess in the right arm. Standard of care treatment was administered. Within a week, a drastic improvement of the wall thickening was noted, which can be, regardless of the biological markers, a surrogate marker of an infectious aortitis.

Comparison of mean diffusivity, R2* relaxation rate and morphometric biomarkers for the clinical differentiation of parkinsonism.

INTRODUCTION: Quantitative biomarkers for clinical differentiation of parkinsonian syndromes are still lacking. Our aim was to evaluate the value of combining clinically feasible manual measurements of R2* relaxation rates and mean diffusivity (MD) in subcortical regions and brainstem morphometric measurements to improve the discrimination of parkinsonian syndromes. METHODS: Twenty-two healthy controls (HC), 25 patients with Parkinson's disease (PD), 19 with progressive supranuclear palsy (PSP) and 27 with multiple system atrophy (MSA, 21 with the parkinsonian variant -MSAp, 6 with the cerebellar variant -MSAc) were recruited. R2*, MD measurements and morphometric biomarkers including the midbrain to pons area ratio and the Magnetic Resonance Parkinsonism Index (MRPI) were compared between groups and their diagnostic performances were assessed. RESULTS: Morphometric biomarkers discriminated better patients with PSP (ratio: AUC 0.89, MRPI: AUC 0.89) and MSAc (ratio: AUC 0.82, MRPI: AUC 0.75) from other groups. R2* and MD measurements in the posterior putamen performed better in separating patients with MSAp from PD (R2*: AUC 0.89; MD: AUC 0.89). For the three-class classification "MSA vs PD vs PSP", the combination of MD and R2* measurements in the posterior putamen with morphometric biomarkers (AUC: 0.841) outperformed each marker separately. At the individual-level, there were seven discordances between imaging-based prediction and clinical diagnosis involving MSA. Using the new Movement Disorder Society criteria for the diagnosis of MSA, three of these seven patients were clinically reclassified as predicted by quantitative imaging. CONCLUSION: Combining R2* and MD measurements in the posterior putamen with morphometric biomarkers improves the discrimination of parkinsonism.

A post-COVID-19 Aspergillus fumigatus posterior mediastinitis: Case report.

Invasive aspergillosis is a life-threatening condition of the immunocompromised, with a low occurrence reported in the immunocompetent. Although usually made by invasive methods, its early diagnosis is the cornerstone of a better prognosis as it yields a timely management and thus a lower mortality risk. Mediastinal invasion by Aspergillus is, like any fungal mediastinitis, uncommon and usually results from a hematogeneous or a contiguous spread, a postoperative fungal infection, a complication of a descending necrotizing fasciitis, or from an esophageal perforation. We report a case of a diabetic patient with a previous history of hospitalization 2 months earlier for a COVID-19 infection, otherwise healthy, presenting with an unresolving dorsal pain. A malignancy was expected but further work-up showed in fine a posterior mediastinitis due to Aspergillus fumigatus. Thus, fungal etiologies are to be included as a differential while diagnosing a posterior mediastinitis even in a relatively immunocompetent patient and with no evident route of entry.