CTPAs are, nevertheless, associated with a significant radiation dose and may not be suitable for all patients, for example patients who are pregnant or have renal impairment. acute, scans with no acute pulmonary pathology; PE, pulmonary embolus; other, patients with other pathologies on CTPA including lobar pneumonia, pleural effusion, etc. Open in a separate window Fig. 2 Examples of lung parenchymal changes on CT pulmonary angiogram (CTPA). Parenchymal changes are indicated by the yellow arrows. a?=?2020 CTPA positive for PE with associated parenchymal changes [ground glass opacities (GGOs)]; b?=?2020 CTPA Mouse monoclonal to BDH1 negative for PE with multiple peripherally distributed GGOs; c?=?2020 CTPA negative for PE with a single peripheral GGO; d?=?2019 CTPA negative for PE with peri\bronchial GGOs; e?=?2020 CTPA negative for PE with right lower lobe consolidation; f?=?an example of more extensive parenchymal changes in a patient who had a positive PCR test for COVID\19. The data also revealed differences in alternative lung parenchymal pathology identified on CTPA (Table?2). In 2019, 34.1% ( em n /em ?=?29/85) patients had no acute pulmonary pathology reported compared with 52.0% ( em n /em ?=?76/146) patients in 2020. Conversely, in 2019 49.4% ( em n /em ?=?42/85) patients were found to have an alternative cause for their symptoms from the CTPA scan compared with just 15.0% ( em n /em ?=?22/146) in 2020 ( em P /em ?=?0.010) (Table?2), possibly indicating milder or later stage COVID\19 infection, with resolution of parenchymal changes. CTPAs which were positive for PE in outpatients presenting in each time period were also reviewed to determine whether these patients had associated areas of parenchymal change. Overall, only 3.9% ( em n /em ?=?6/152) outpatient scans from 2020 and 4.5% ( em n /em ?=?4/89) scans from 2019 had a PE\positive CTPAs (Table?2). In 2020, 5/6 patients with PE\positive CTPAs had parenchymal changes, compared with 3/4 patients in 2019 (Table?2). Serological evaluation for COVID\19 antibodies Finally, correlation between PE\negative CTPA findings in the 2020 cohort ( em n /em ?=?146) and COVID\19 serology was evaluated. As COVID\19 was not suspected as the primary diagnosis in this patient cohort, COVID\19 PCR testing was not performed when they initially presented to hospital. In total, 39 patients (26.5%) of the PE\negative cohort from 2020 attended for a COVID\19 antibody test with a mean time of 101?days (standard deviation??30?days) between the CTPA and COVID\19 antibody test. Only 3 patients tested positive for COVID\19 antibodies with 2 of the antibody positive patients having areas of parenchymal change on CT. Of the 36 patients negative for COVID\19 antibodies, 6 had likely COVID\19 based on the CTPA BSTI grading, 6 had areas of parenchymal change, 19 had normal CTPAs, and 5 had an alternative cause for their symptoms. Notably, none of the 6 patients with radiologically likely COVID\19 pneumonia who attended for antibody testing were positive for COVID\19 antibodies ( em n /em ?=?0/6). Discussion This study showed increased hospital presentation of Vitamin K1 suspected PE in 2020 compared to 2019, and in 2020, 32.8% of these patients had pulmonary parenchymal changes either characteristic of COVID\19 or suggestive of viral infection, including 11 patients whose CTPA was Vitamin K1 likely/suspicious for COVID\19. Most patients did not have typical COVID\19 pneumonia symptoms except for a dry cough in 21.2% of cases, which is also a PE feature, but all presented with chest pain more typical of PE. More severe COVID\19 cases are typically associated with reduced oxygen saturation, fever, lymphopenia and substantially elevated D\Dimer and CRP values, which was not observed in our cohort. Although only 25.6% patients contacted attended for voluntary COVID\19 antibody testing, none Vitamin K1 of the 6 patients with a CTPA which was likely/suspicious for COVID\19 had COVID\19 antibodies. Thus overall, the significant increase in parenchymal changes in 2020 compared with 2019 is likely to be related to COVID\19 infection that was contained and thus may not have generated systemic humoral immune responses. Fewer patients presented to hospital in 2020 compared with 2019, including fewer outpatient CTPAs, possibly reflecting public reticence to attend hospital during the pandemic. Similarly, pressures on hospital trusts to avoid any hospital admission where possible, in efforts to reduce nosocomial transmission of the disease, may account for the reduction in inpatient CTPAs in 2020 compared with 2019. However, interestingly whilst 154 outpatients in 2020 presented with chest pain compared with 89 in 2019, the number of confirmed PEs was similar. This further supports that chest pain may indeed by a presentation for mild COVID\19 infection masquerading as suspected PE,.