The role of chest CT in deciphering interstitial lung involvement: systemic sclerosis versus COVID-19.

OBJECTIVE: The aim of this study was to identify the main CT features that may help in distinguishing a progression of interstitial lung disease (ILD) secondary to SSc from COVID-19 pneumonia. METHODS: This multicentric study included 22 international readers grouped into a radiologist group (RADs) and a non-radiologist group (nRADs). A total of 99 patients, 52 with COVID-19 and 47 with SSc-ILD, were included in the study. RESULTS: Fibrosis inside focal ground-glass opacities (GGOs) in the upper lobes; fibrosis in the lower lobe GGOs; reticulations in lower lobes (especially if bilateral and symmetrical or associated with signs of fibrosis) were the CT features most frequently associated with SSc-ILD. The CT features most frequently associated with COVID- 19 pneumonia were: consolidation (CONS) in the lower lobes, CONS with peripheral (both central/peripheral or patchy distributions), anterior and posterior CONS and rounded-shaped GGOs in the lower lobes. After multivariate analysis, the presence of CONs in the lower lobes (P < 0.0001) and signs of fibrosis in GGOs in the lower lobes (P < 0.0001) remained independently associated with COVID-19 pneumonia and SSc-ILD, respectively. A predictive score was created that was positively associated with COVID-19 diagnosis (96.1% sensitivity and 83.3% specificity). CONCLUSION: CT diagnosis differentiating between COVID-19 pneumonia and SSc-ILD is possible through a combination of the proposed score and radiologic expertise. The presence of consolidation in the lower lobes may suggest COVID-19 pneumonia, while the presence of fibrosis inside GGOs may indicate SSc-ILD.

Hippocampal Electrical Activity and Behaviour in Rabbits during Adaptation to a Novel Semi-Natural Environment.

The aim of the present experiment was to show possible modifications in behaviour and hippocampal electrical activity during adaptation to a novel semi-natural environment. Rabbits with chronic implanted electrodes in the hippocampus were introduced into a large, natural, open-air enclosure. Their spontaneous behaviour was studied for 3 days. Electrical activity was recorded by telemetry, stored with behaviour on a video-tape, and then analysed. Behaviour was divided into categories and variables. The categories were: activity directed towards the environment (including exploratory movements, scanning, marking, etc.) and self-directed activities (such as eating, drinking, self-grooming, etc.). Exploratory elements were observed and classified according to a spatial and a temporal criterion. The rabbits showed a progressive adaptation to the environment with quantitative and qualitative reduction in exploration and an increment in quiet immobility and inspective activities. Three EEG patterns were recognized from autocorrelation and spectral analysis: high rhythmicity theta (HRSA) with specific relationship to voluntary movements, such as exploration and running; low rhythmicity theta (LRSA) in signalling activities or self-directed behaviour and during postural and reactive immobility; and irregular activity (IA) sometimes seen in the same immobile behaviour. The results show that some behaviours (exploration, alert and postural immobility, self-directed activity) are correlated to specific patterns of electrical activity in the hippocampus and, as exploratory behaviour decreased with time, there was a concomitant increase in EEG frequency.