# New Approaches to AI Methods for Screening Cardiomegaly on Chest Radiographs
## 3 Results
### Transverse Cardiac Diameter  
The means and SDs of TCDs were slightly higher when calculated from either manual or automated segmentations than when manually read (162.7 \(\pm\) 25.8, CV = 15.9 for the automatic segmentation model; 162.7 \(\pm\) 29.5, CV = 18.1 for the manual segmentation model; and 152.4 \(\pm\) 25.5, CV = 16.7 for the direct manual measurements; Figure 3). The results of the Wilcoxon test showed that there were no statistically significant differences between the TCDs measured from direct manual reading, manual segmentations, and automatic segmentation (statistic = 608.0, \(p\)-value = 0.78 for manual-automatic segmentation comparison; statistic = 111.0, \(p\)-value = 3.73 for direct measurements-manual segmentation comparison; and statistic = 37.0, \(p\)-value = 6.76 for direct measurement-automatic \begin{table}
\begin{tabular}{c c c} \hline \hline
**Cardiomegaly Definition Based on CMR** & **Method of Measurements** & **AUC** \\ \hline \multirow{4}{*}{Both elevated LVEDV and enlarged LVM} & Manual reading & 0.747 \\ \cline{2-3}  & Manual segmentation & 0.759 \\ \cline{2-3}  & Automatic segmentation & 0.711 \\ \hline \multirow{4}{*}{Both elevated LVEDV/BSA and enlarged LVM/BSA} & Manual reading & 0.823 \\ \cline{2-3}  & Manual segmentation & 0.796 \\ \cline{2-3}  & Automatic segmentation & 0.753 \\ \hline \multirow{4}{*}{Elevated LVEDV} & Manual reading & 0.858 \\ \cline{2-3}  & Manual segmentation & 0.877 \\ \cline{2-3}  & Automatic segmentation & 0.864 \\ \hline \multirow{4}{*}{Enlarged LVM} & Manual reading & 0.739 \\ \cline{2-3}  & Manual segmentation & 0.705 \\ \cline{2-3}  & Automatic segmentation & 0.659 \\ \cline{2-3}  & Manual reading & 0.894 \\ \cline{2-3}  & Manual segmentation & 0.889 \\ \cline{2-3}  & Automatic segmentation & 0.897 \\ \hline \multirow{4}{*}{Enlarged LVM/BSA} & Manual reading & 0.823 \\ \cline{2-3}  & Manual segmentation & 0.796 \\ \cline{1-1} \cline{2-3}  & Automatic segmentation & 0.753 \\ \hline \hline \end{tabular} Abbreviations: BSA—body surface area; CMR—cardiac magnetic resonance; LVEDV—left ventricle end-diastolic volume; LVM—left ventricular mass.  
\end{table} 
Table 2: Results of receiver operating characteristic analysis for cardiothoracic ratio. segmentation comparison). The values of the TCDs measured from direct manual reading, manual segmentations, and automatic segmentations are shown in Appendix A Table A4. Our analysis revealed a greater correlation of TCDs measured from manual segmentation with automatic segmentation when compared to the correlation between segmentation models and direct manual measurements (R = 0.946 vs. R = 0.910 vs. R = 879, Appendix A Figure A5). When analyzing the correlation between the AI model and direct manual measurements based on positive and negative cardiomegaly diagnoses established on the basis of various CMR definitions, for both positive and negative cardiomegaly diagnoses, greater correlations were observed for manual segmentation vs. automatic segmentation (Appendix A Table A5). The relationship between TCD measurements based on the manual and automatic segmentations and manual reading were also examined using Bland-Altman plots (Figure 4). Figure 4: Bland–Altman plots of deep learning models based on manual (**A**) and automatic (**B**) segmentation compared to direct manual measurements. Figure 3: The transverse cardiac diameter from direct manual measurement, manual segmentation, and automatic segmentation. Box plots show the medians and first and third quartiles in boxes, as well as the minimum and maximum values of the cardiothoracic ratio from manual measurement, manual segmentation, and automatic segmentation. Abbreviations: TCD—transverse cardiac diameter. The McNemar test revealed that in the majority of cases, the TCD measurements made from the manual and automatic segmentations, as well as direct manual measurements, were in agreement with the CMR diagnosis.