Usefulness of Quantitative Analysis Using Relative Electron Density-Based Image of Subsolid Nodule in Chest HRCT

To study the usefulness of quantitative analysis using the relative electron density-based image in the diagnosis of subsolid nodule by chest high-resolution CT. The phantom study measured the CT number(HU), relative electron density(%EDW) and maximum diameter of the nodules by placing artificial nodules in the chest phantom. The patient study was conducted on 172 patients with subsolid nodules from April 2022 to January 2023. The volume and diameter of subsolid nodules in the CT number-based image and relative electron density-based image were measured separately after dividing the two groups: mixed ground-glass nodule and pure ground-glass nodule. The correlation studied between measuring the CT number(HU) and relative electron density(%EDW) by setting the region of interest. The CT number(HU) and diameter values in the phantom study were not significantly different from the actual values of the artificial nodules.(P>0.05) As a result of the patient study, the volume and diameter of subsolid nodules were increased in the relative electron density-based image compared to the CT number-based image for both the mixed ground-glass nodule and pure ground-glass nodule groups.(P<0.05) The CT number(HU) and relative electron density(%EDW) showed a strong positive correlation in both the phantom and patient study.(P<0.05) Providing visual imaging information using CT number-based and relative electron density-based images simultaneously can offer many advantages in establishing future treatment plans through accurate quantitative analysis of subsolid nodules.