OpenAI’s GPT-4V reliably identified the imaging modality and anatomic region but could not safely detect, classify, or rule out abnormalities on single MRI, CT, and radiographic images.

COVID-19 is frequently complicated by venous thromboembolism (VTE). Computed tomography (CT) of the chest—primarily usually conducted as low-dose, non-contrast enhanced CT—plays an important role in the diagnosis and follow-up of COVID-19 pneumonia. Performed as contrast-enhanced CT pulmonary angiography, it can reliably detect or rule-out pulmonary embolism (PE). Several imaging characteristics of COVID-19 pneumonia have been described for chest CT, but no study evaluated CT findings in the context of VTE/PE. In our retrospective study, we analyzed clinical, laboratory and CT imaging characteristics of 50 consecutive patients with RT-PCR proven COVID-19 pneumonia who underwent contrast-enhanced chest CT at two tertiary care medical centers. All patients with RT-PCR proven COVID-19 pneumonia and contrast-enhanced chest CT performed at two tertiary care hospitals between March 1st and April 20th 2020 were retrospectively identified. Patient characteristics (age, gender, comorbidities), symptoms, date of symptom onset, RT-PCR results, imaging results of CT and leg ultrasound, laboratory findings (C-reactive protein, differential blood count, troponine, N-terminal pro-B-type natriuretic peptide (NT-proBNP), fibrinogen, interleukin-6, D-dimer, lactate dehydrogenase (LDH), creatine kinase (CK), creatine kinase muscle-brain (CKmb) and lactate,) and patient outcome (positive: discharge or treatment on normal ward; negative: treatment on intensive care unit (ICU), need for mechanical ventilation, extracorporeal membrane oxygenation (ECMO), or death) were analyzed. Follow-up was performed until May 10th. Patients were assigned to two groups according to two endpoints: venous thromboembolism (VTE) or no VTE. For statistical analysis, univariate logistic regression models were calculated. This study includes 50 patients. In 14 out of 50 patients (28%), pulmonary embolism was detected at contrast-enhanced chest CT. The majority of PE was detected on CTs performed on day 11–20 after symptom onset. Two patients (14%) with PE simultaneously had evidence of deep vein thrombosis. 15 patients (30%) had a negative outcome (need for intensive care, mechanical ventilation, extracorporeal membrane oxygenation, or death), and 35 patients (70%) had a positive outcome (transfer to regular ward, or discharge). Patients suffering VTE had a statistically significant higher risk of an unfavorable outcome (p = 0.028). In univariate analysis, two imaging characteristics on chest CT were associated with VTE: crazy paving pattern (p = 0.024) and air bronchogram (n = 0.021). Also, elevated levels of NT-pro BNP (p = 0.043), CK (p = 0.023) and D-dimers (p = 0.035) were significantly correlated with VTE. COVID-19 pneumonia is frequently complicated by pulmonary embolism (incidence of 28% in our cohort), remarkably with lacking evidence of deep vein thrombosis in nearly all thus affected patients of our cohort. As patients suffering VTE had an adverse outcome, we call for a high level of alertness for PE and advocate a lower threshold for contrast-enhanced CT in COVID-19 pneumonia. According to our observations, this might be particularly justified in the second week of disease and if a crazy paving pattern and / or air bronchogram is present on previous non-enhanced CT.

The novel coronavirus (Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)), which originated in China, has caused a worldwide pandemic [1]. The disease caused by SARS-CoV-2 is referred to as Coronavirus Disease 2019 (COVID-19). During the pandemic and probably beyond, radiologists performing CT examinations of patients with symptoms of a respiratory infection will inevitably be asked if it could be a case of COVID-19 pneumonia. On the other hand, if a chest CT performed for another indication yields abnormal results, the radiologist must consider the possibility of incidental COVID-19 pneumonia, communicate this to the referring physician as quickly as possible, and introduce the appropriate hygiene measures in his/her own department.

Quantitative analysis of chest computed tomography (CT) usually requires non-contrast scans. Multi-energy CT-derived virtual non-contrast (VNC) images may obviate additional true non-contrast (TNC) scans. We aimed to quantitatively compare virtual and true non-contrast images, with a focus on regional differences in pulmonary tissue. This bi-center retrospective, IRB-approved study included consecutive patients who received contrast-enhanced dual-energy and non-contrast chest CT scans within one year between April 2018 and December 2022. Scans were co-registered and semi-manually segmented into various volumes of interest: whole lung, center/periphery, ventral/dorsal half and upper/middle/lower third. The mean lung density, high and low attenuation volumes and the lower 15th percentile were computed from the VNC and TNC scans for each volume. Correlation and agreement were assessed using Pearson's and intraclass correlation coefficients and Bland-Altman analysis. Subgroup analyses involved body mass index and markers of pulmonary emphysema. Forty-eight patients were included (26 females, median age: 63 years, interquartile range: 58-69). Pearson's and intraclass correlation coefficients > 0.9 demonstrated high correlation and agreement for the mean lung density, low attenuation volume and the lower 15th percentile across the whole lung. The agreement for high attenuation volume was slightly less pronounced (intraclass correlation coefficient, 0.84 [95% confidence interval: 0.73, 0.91]). Regional differences were observed, for example, concerning the mean lung density with mean differences (HU_VNC minus HU_TNC) of -5.71 HU [-11.07, -0.35], 1.62 HU [-2.98, 6.23] and 5.77 HU [-0.47, 12.01] for the upper, middle and lower third, respectively. Although slight regional differences were observed, quantitative analysis can be reliably performed using VNC images.