The impact of technical factors on the chest radiographic findings in COVID-19 pneumonia.

BACKGROUND: Published coronavirus disease 2019 (COVID-19) chest X-ray (CXR) severity scoring systems do not consider the impact of technical factors on radiographic findings. This study aimed to describe the technical features of COVID-19 pneumonia CXRs, determine their impact on CXR interpretation and reappraise published COVID-19 CXR severity scoring systems based on these findings. METHODS: Admission frontal CXRs of 100 consecutive adults with proven COVID-19 pneumonia were analysed for technical features (projection, inspiratory excursion, exposure, vertical rotation) and pulmonary opacification. Descriptive statistics were evaluated. Kendall's coefficient of concordance was used to assess observer agreement. One-way analysis of variance (ANOVA) was used to determine the association between technical factors and opacification. Levene's test for homogeneity-of-variance and the Welch test were conducted where applicable. For inspiratory excursion, correlations were also calculated. Findings informed a review of published COVID-19 CXR severity scoring systems. RESULTS: Poor inspiratory excursion obscured the lower lung zones in 41 cases and was associated with increased opacification in the visible (mid and upper) zones. Under- (n = 13) and over-penetration (n = 39) were associated with increased and decreased basal opacification, respectively. Eighty cases (80%) showed vertical rotation, without significant impact on opacification. Re-appraisal of published COVID-19 CXR scoring systems revealed that all simply assessed the visible lung fields, without considering inspiration or penetration. CONCLUSION: Published COVID-19 CXR severity scoring systems could be refined by appropriate consideration of inspiratory excursion and penetration. More broadly, technical considerations should inform all CXR interpretation. CONTRIBUTION: This study advocates incorporating technical factor assessment into CXR severity scoring systems.