[The effects of quarantine for SARS-CoV-2 on sleep: An online survey]. / Les effets de confinement SARS-CoV-2 sur le sommeil : enquête en ligne au cours de la quatrième semaine de confinement.

OBJECTIVES: Explore the evolution of sleep during the SARS-CoV-2 quarantine period and define associated factors. METHODS: An online survey of patients in quarantine. Questions targeted the conditions of quarantine, sleep related behaviours and exposure to factors known to affect sleep and circadian rhythms (light exposure and sport). RESULTS: In all, 1777 participants were included: 77% women and 72% aged 25-54 years. Quarantine conditions were most frequently in couples with children (36%) and in a house with a garden (51%). Forty-seven percent of participants reported a decrease in sleep quality during quarantine. Factors associated with a reduction in sleep quality by logistic regression were sleep reduction (OR 15.52 P<0.001), going to bed later (OR 1.72 P<0.001), getting up earlier (2.18 P=0.01), an increase in sleep-wake irregularity (OR 2.29 P<0.001), reduced exposure to daylight (OR 1.46 P=0.01) and increased screen use in the evenings (OR 1.33 P=0.04). CONCLUSION: Sleep quality tended to reduce during quarantine and this was associated with changes in sleep behaviours and light exposure, especially in the evening. In order to optimise sleep during quarantine, regular sleep and wake times, at least 1hour exposure to daylight and a reduction of screen use in the evenings are suggested.

Comparison of Iterative Model Reconstruction versus Filtered Back-Projection in Pediatric Emergency Head CT: Dose, Image Quality, and Image-Reconstruction Times.

BACKGROUND AND PURPOSE: Noncontrast CT of the head is the initial imaging test for traumatic brain injury, stroke, or suspected nonaccidental trauma. Low-dose head CT protocols using filtered back-projection are susceptible to increased noise and decreased image quality. Iterative reconstruction noise suppression allows the use of lower-dose techniques with maintained image quality. We review our experience with children undergoing emergency head CT examinations reconstructed using knowledge-based iterative model reconstruction versus standard filtered back-projection, comparing reconstruction times, radiation dose, and objective and subjective image quality. MATERIALS AND METHODS: This was a retrospective study comparing 173 children scanned using standard age-based noncontrast head CT protocols reconstructed with filtered back-projection with 190 children scanned using low-dose protocols reconstructed with iterative model reconstruction. ROIs placed on the frontal white matter and thalamus yielded signal-to-noise and contrast-to-noise ratios. Volume CT dose index and study reconstruction times were recorded. Random subgroups of patients were selected for subjective image-quality review. RESULTS: The volume CT dose index was significantly reduced in studies reconstructed with iterative model reconstruction compared with filtered back-projection, (mean, 24.4 ± 3.1 mGy versus 31.1 ± 6.0 mGy, P < .001), while the SNR and contrast-to-noise ratios improved 2-fold (P < .001). Radiologists graded iterative model reconstruction images as superior to filtered back-projection images for gray-white matter differentiation and anatomic detail (P < .001). The average reconstruction time of the filtered back-projection studies was 101 seconds, and with iterative model reconstruction, it was 147 seconds (P < .001), without a practical effect on work flow. CONCLUSIONS: In children referred for emergency noncontrast head CT, optimized low-dose protocols with iterative model reconstruction allowed us to significantly reduce the relative dose, on average, 22% compared with filtered back-projection, with significantly improved objective and subjective image quality.