Impact of body mass index on the reliability of the CT0–4 grading system: a comparison of computed tomography protocols

Abstract

BACKGROUND: The increased frequency of chest computed tomography utilization in the fight against COVID-19 has made usage of low-dose computed tomography necessary to reduce the radiation dose while preserving diagnostic quality. However, in the published literature, there were no data on the effect of body mass index on low-dose computed tomography accuracy in patients with COVID-19. AIM: To assess the effect of patient body mass index on the level of agreement between radiologists interpreting standard-dose computed tomography and low-dose computed tomography in COVID-19-associated pneumonia using visual semiquantitative CT 04 scale. MATERIALS AND METHODS: In this retrospective multicenter study, each participant underwent two consecutive chest scans at a single visit using standard-dose and low-dose protocols. Standard-dose and low-dose computed tomography with pulmonary and soft tissue kernels were interpreted using a visual semiquantitative CT 04 grading system. Data for each protocol were grouped by body mass index value (threshold value for pathology was equal to 25 kg/m2). Agreement was calculated based on binary and weighted classifications. One-way ANOVA analysis of variance was used to assess the presence of statistically significant differences in the mean for the groups. RESULTS: Two hundred thirty patients met the established inclusion criteria for the study. The experts processed 4 studies for each patient: standard-dose and low-dose computed tomography with pulmonary and soft tissue kernels. The proportion of normal-weight patients was 31% (71 subjects), and the samples median body mass index was 27.5 (18.3; 48.3) kg/m2. There were no statistically significant differences in intergroup pairwise comparisons for both the binary and weighted classifications (p values were 0.09 and 0.12, respectively). The group of overweight patients was further subdivided according to the degrees of obesity; however, the results were invariant to this division (no statistically significant differences: for the most different body mass index groups normal and 3rd degree obesity p-value 0.17). CONCLUSION: Body mass index does not affect chest standard-dose and low-dose computed tomography interpretation in COVID-19 using the visual semiquantitative CT 04 grading system.