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Objective: Frequency of normal chest CT in symptomatic COVID-19 patients as well as the outcome of these patients remains unknown. The objectives of this work were to assess the incidence of initially normal chest CT in a cohort of consecutive confirmed COVID-19 patients with respiratory symptoms and to compare their clinical characteristics and their outcome to matched patients with typical COVID-19 lesions at initial CT. Methods: From March 6th to April 22nd, all consecutive adult patients referred to the COVID-19 clinic of our Emergency Department were retrospectively analyzed. Each patient with a positive SARS-CoV-2 RT-PCR and a normal initial chest CT after second reading was 1:1 matched based on sex, age and date of CT acquisition to a patient with positive RT-PCR and initial chest CT with typical COVID-19 lesions. Clinical data, laboratory results and outcomes (major being mechanical ventilation and/or death) were compared between both groups, using Wilcoxon signed-rank test, McNemar's chi-squared test and/or exact McNemar's test where appropriate. Results: Fifty-seven chest CT out of 1091 (5.2%, 95% CI 4.0–6.7) in symptomatic patients with positive RT-PCR were normal, with a median onset of symptoms of 4.5 days (IQR [1.25–10.25]). After a median follow-up of 43 days, death and/or mechanical ventilation occurred in 3 patients (5.3%) in the study group, versus 11 (19.3%) in the control group (p = 0.011). Conclusions: Normal initial chest CT occurred in 5.2% of symptomatic confirmed COVID-19 cases in our cohort. While better than those with abnormal chest CT, outcome was not entirely benign with 5.3% death and/or mechanical ventilation. Key Points: • In a cohort of 1091 symptomatic COVID-19 patients, initial chest CT was normal in 5.2% of cases. • Normal chest CT in confirmed COVID-19 is frequent even when onset of symptoms is greater than 3 days. • The outcome of COVID-19 patients with initial normal chest CT, while better than those with abnormal CT, was not entirely benign with 5.3% death and/or mechanical ventilation. [ABSTRACT FROM AUTHOR]

Objectives: To retrospectively investigate the incidence of acute adrenal infarction (AAI) in patients who underwent chest CT for severe SARS-CoV-2 infection and to correlate findings with prognosis. Methods: The local ethics committee approved this retrospective study and waived the need of informed consent. From March 9 to April 10, 2020, all patients referred to our institution for a clinical suspicion of COVID-19 with moderate to severe symptoms underwent a chest CT for triage. Patients with a/parenchymal lesion characteristics of COVID-19 involving at least 50% of lung parenchyma and b/positive RT-PCR for SARS-CoV-2 were retrospectively included. Adrenal glands were reviewed by two independent readers to look for AAI. Additional demographics and potential biological markers of adrenal insufficiency were obtained. Correlations with ICU stay and mortality were sought. Results: Out of the 219 patients with critical (n = 52) and severe lung (n = 167) parenchyma lesions, 51 (23%) had CT scan signs of AAI, which was bilateral in 45 patients (88%). Four patients had an acute biological adrenal gland insufficiency (8%). Univariate analysis in AAI+ patients demonstrated a higher rate of ICU stay (67% vs. 45%, p < 0.05) and a longer stay (more than 15 days for 31% for AAI+ vs. 19%, p < 0.05) compared with AAI− patients. Mortality rate was similar (27%, p = 0.92). Conclusions: Acute adrenal infarction on initial chest evaluation of severe COVID-19 is frequent (51/219, 23%) and might be a sign of poorer prognosis. Key Points: • Acute adrenal infarction on initial chest CT evaluation of severe COVID-19 is frequent (51/219). • AAI might be a factor of poorer prognosis, with increased rate of ICU hospitalization and length of stay. [ABSTRACT FROM AUTHOR]

Objectives: Diagnostic performance and potential radiation dose reduction of wide-area detector CT sequential acquisition ("wide-volume" acquisition (WV)) in unenhanced chest examination are unknown. This study aims to assess the image quality, the diagnostic performance, and the radiation dose reduction of WV mode compared with the classical helical acquisition for lung parenchyma analysis in an ultra-low-dose (ULD) protocol.Methods: After Institutional Review Board Approval and written informed consent, 64 patients (72% men; 67.6 ± 9.7 years old; BMI 26.1 ± 5.3 kg/m2) referred for a clinically indicated unenhanced chest CT were prospectively included. All patients underwent, in addition to a standard helical acquisition (120 kV, automatic tube current modulation), two ULD acquisitions (135 kV, fixed tube current at 10 mA): one in helical mode and one in WV mode. Image noise, subjective image quality (5-level Likert scale), and diagnostic performance for the detection of 9 predetermined parenchymal abnormalities were assessed by two radiologists and compared using the chi-square or Fisher non-parametric tests.Results: Subjective image quality (4.2 ± 0.7 versus 4.2 ± 0.8, p = 0.56), image noise (41.7 ± 8 versus 40.9 ± 8.7, p = 0.3), and diagnostic performance were equivalent between ULD WV and ULD helical. Radiation dose was significantly lower for the ULD WV acquisition (mean dose-length product 14.1 ± 1.3 mGy cm versus 15.8 ± 1.3, p < 0.0001).Conclusion: An additional 11% dose reduction is achieved with the WV mode in ULD chest CT with fixed tube current, with equivalent image quality and diagnostic performance when compared with the helical acquisition.Key Points: • Image quality and diagnostic performance of ultra-low-dose unenhanced chest CT are identical between wide-volume mode and the reference helical acquisition. • Wide-volume mode allows an additional radiation dose reduction of 11% (mean dose-length product 14.1 ± 1.3 mGy cm versus 15.8 ± 1.3, p < 0.0001). [ABSTRACT FROM AUTHOR]

Objectives: To investigate the radiation dose exposure, image quality, and diagnostic performance of enhanced 100-kVp abdominopelvic single-energy CT protocol with tin filter (TF).Methods: Ninety-three consecutive patients referred for a single-phase enhanced abdominopelvic CT were prospectively included after informed consent. They underwent in addition to a standard protocol (SP) an acquisition with TF. Both examinations were performed on a third-generation dual-source CT system (DSCT), in single energy, using automatic tube current modulation, identical pitch, and identical level of iterative reconstruction. Radiation metrics were compared. Size-specific dose estimates (SSDE), contrast to noise ratio (CNR), and figure of merit (FOM) were calculated. Diagnostic confidence for the assessment of a predetermined list of abdominal lesions was rated by two independent readers.Results: The mean dose of the TF protocol was significantly lower (CDTI 1.56 ± 0.43 mGy vs. 8.13 ± 3.32, p < 0.001; SSDE 9.94 ± 3.08 vs. 1.93 ± 0.39, p < 0.001), with an effective dose close to 1 mSv (1.14 mSv ± 0.34; p < 0.001). TF group exhibited non-significant lower liver CNR (2.76 vs. 3.03, p = 0.56) and was more dose efficient (FOM 10.6 vs. 2.49/mSv, p < 0.001) in comparison to SP. The mean diagnostic confidence for visceral, bone, and peritoneal tumors was equivalent between both groups.Conclusions: Enhanced 100-kVp abdominopelvic CT acquired after spectral shaping with tin filtration can achieve similar diagnostic performance and CNR compared to a standard CT protocol, while reducing the radiation dose by 81%.Key Points: • 100-kVp spectral filtration enables enhanced abdominal CT with high-dose efficiency. • The radiation dose reaches the 1-mSv range. • Predetermined abdominopelvic lesions can be assessed without impairing on diagnostic confidence. [ABSTRACT FROM AUTHOR]