Pulmonary CT angiography in the first wave of the COVID-19 pandemic: Comparison between patients with and without infection and with a pre-pandemic series

BACKGROUND AND AIMS: To analyze the diagnostic performance of pulmonary CT angiography and to compare different D-dimer cutoffs for the diagnosis of acute pulmonary embolism in patients with and without SARS-CoV-2 infections. MATERIALS AND METHODS: We retrospectively analysed all consecutive pulmonary CT angiography studies done for suspected pulmonary embolism in a tertiary hospital during two time periods: the first December 2020 through February 2021 and the second December 2017 through February 2018. D-dimer levels were obtained less than 24 h before the pulmonary CT angiography studies. We analysed the sensitivity, specificity, positive and negative predictive values, area under the receiver operating curve (AUC), and pattern of pulmonary embolism for six different values of D-dimer and the extent of the embolism. During the pandemic period, we also analysed whether the patients had COVID-19. RESULTS: After excluding 29 poor-quality studies, 492 studies were analysed; 352 of these were done during the pandemic, 180 in patients with COVID-19 and 172 in patients without COVID-19. The absolute frequency of pulmonary embolism diagnosed was higher during the pandemic period (34 cases during the prior period and 85 during the pandemic; 47 of these patients had COVID-19). No significant differences were found in comparing the AUCs for the D-dimer values. The optimum values calculated for the receiver operating characteristic curves differed between patients with COVID-19 (2200 mcg/l), without COVID-19 (4800 mcg/l), and diagnosed in the prepandemic period (3200 mcg/l). Peripheral distribution of the emboli was more common in patients with COVID-19 (72%) than in those without COVID-19 and than in those diagnosed before the pandemic [OR 6.6, 95% CI: 1.5–24.6, p < 0.05 when compared to central distribution]. CONCLUSIONS: The number of CT angiography studies and the number of pulmonary embolisms diagnosed during the pandemic increased due to SARS-CoV-2 infection. The optimal d-dimer cutoffs and the distribution of the pulmonary embolisms differed between the groups of patients with and without COVID-19.