Quantitative and semi-quantitative CT assessments of lung lesion burden in COVID-19 pneumonia

Abstract

This study aimed to clarify and provide clinical evidence for which computed tomography (CT) assessment method can more appropriately reflect lung lesion burden of the COVID-19 pneumonia. A total of 244 COVID-19 patients were recruited from three local hospitals. All the patients were assigned to mild, common and severe types. Semi-quantitative assessment methods, e.g., lobar-, segmental-based CT scores and opacity-weighted score, and quantitative assessment method, i.e., lesion volume quantification, were applied to quantify the lung lesions. All four assessment methods had high inter-rater agreements. At the group level, the lesion load in severe type patients was consistently observed to be significantly higher than that in common type in the applications of four assessment methods (all the p < 0.001). In discriminating severe from common patients at the individual level, results for lobe-based, segment-based and opacity-weighted assessments had high true positives while the quantitative lesion volume had high true negatives. In conclusion, both semi-quantitative and quantitative methods have excellent repeatability in measuring inflammatory lesions, and can well distinguish between common type and severe type patients. Lobe-based CT score is fast, readily clinically available, and has a high sensitivity in identifying severe type patients. It is suggested to be a prioritized method for assessing the burden of lung lesions in COVID-19 patients.

Figure 1

Manual Lesion segmentation by Radiologist 3 and Radiologist 4. This is an example of lesion segmentation in a 68 year old female patient from Site 1. She was assigned to the common type of COVID-19 patients. The Dice similarity coefficient of the segmented inflammatory lesions between Radiologist 3 and Radiologist 4 is 0.812.

Figure 2

The correlation of semiquantitative lesion assessments between Radiologist 1 and Radiologist 2.

Figure 3

The discriminative efficacy (ROC analysis) of lesion assessments, measured by lobar lesion assessment (A), segmental lesion assessment (B), opacity-weighted lesion assessment (C), and lesion volume quantification (D), between severe type and common type patients with COVID-19.

Figure 4

The inter-group differences among COVID-19 patients with different ages. The number of asterisk(s) above each group means the number of inter-group differences showing statistical significance when comparing the lesion load in this group with that in the other group(s) who were younger than them. In each comparison, the asterisk means p < 0.05 with Least Significant Difference adjustment.