# Reliability of Automated Intracranial Volume Measurements by Synthetic Brain MRI in Children
## 3 Results  
We included 124 cranial MRI examinations of 124 unique pediatric patients aged 0 to 18 years (median--2.75 years, 25 th quartile--0.89 years, and 75 th quartile--5.36 years). In total, 59 (47.6%) patients were female, and 65 (52.4%) were male. The inclusion criteria are given in Figure 4. Basic patient characteristics are listed in Table 1.  
Figure 4: Flowchart showing the inclusion and exclusion of patients. The majority of the patients studied were scanned under anesthesia (n = 87, 70.2%; mean age: 2.98 +/\(-\) 2.29 years). Fourteen (11.3%) studies were performed using the \"feed and wrap\" technique (mean age: 0.12 +/\(-\) 0.09 years). Twenty-three (18.5%) studies were performed in cooperative patients (mean age: 11.80 +/\(-\) 4.71 years). Overall, statistically significant differences were calculated for the CSF, BPV, and ICV between manual and SyMRI measurements. The CSF volume was 127.89 +/\(-\) 73.52 mL in the manual assessment and 133.84 +/\(-\) 82.11 mL for the SyMRI analysis, \(p\) = 0.005 (_t_-test). The BPV was also lower on average, showing 990.77 +/\(-\) 359.07 mL in the manual measurements vs. 1024.90 +/\(-\) 362.74 mL in the SyMRI measurements; \(p\) < 0.001 (_t_-test). The ICV was 1120.43 +/\(-\) 389.58 mL in the manual measurements vs. 1158.74 +/\(-\) 393.42 mL in the SyMRI measurements (_p_ < 0.001, _t_-test). There were significant linear correlations between both measurement methods for the CSF (R = 0.963; \(p\) < 0.001), BPV (R = 0.991; \(p\) < 0.001), and ICV (R = 0.992; \(p\) < 0.001). _t_-test comparisons exhibited statistically significant differences for manual CSF vs. SyMRI CSF measurements with a _p_-value of 0.005 and for BPV and ICV measurements with _p_-values lower than 0.001 (compare Figures 5 and 6). [PERSON]'s kappa was 0.66 among all human raters (95% CI of 0.6 to 0.71; \(p\) < 0.001), representing good agreement [25]. The median human rating compared to the SyMRI rating was lower with only moderate agreement, as represented by a [PERSON]'s kappa of 0.45 (95% CI of 0.29 to 0.61; \(p\) < 0.001). [PERSON]'s kappa values for the human raters compared to the SyMRI rating ranged from 0.33 to 0.47. SyMRI CSF volumes in presence and absence of hydrocephalus are given in Figure 7.  
We did not see significant differences in CSF volumes (_p_ = 0.968, _t_-test), the BPV (_p_ = 0.702, _t_-test), or the ICV (_p_ = 0.730, _t_-test) between the manual and SyMRI assessments. Visually, there was a decrease in variability between the manual and SyMRI volume measurements of the CSF with increasing age, as shown in Figure 8b. There were statistically significant differences in the ANOVA test between the four normalized slice position quartiles (_p_ < 0.001), with the lowest count of segmentation errors in the third quartile (cerebrum) compared to the skull vault (fourth quartile, with up to 67% erroneous segmentations, \(p\) < 0.001 in a Bonferroni post-hoc test), the skull base (second quartile, \(p\) = 0.008 in a Bonferroni post-hoc test), and the posterior fossa (first quartile, \(p\) = 0.016 in a Bonferroni post-hoc test). The findings are depicted graphically in Figure 9. \begin{table}
\begin{tabular}{c c c c c} \hline
**Parameter** & **Age (Years)** & **Weight (kg)** & **Body Size (m)** & **BMI** \\ \hline
**Cases (n)** & 124 & 124 & 124 & 124 \\
**Minimum** & 0.0 & 1.8 & 0.4 & 8.6 \\
**Maximum** & 18.1 & 79.0 & 1.7 & 29.7 \\
**25 th percentile** & 0.89 & 7.45 & 0.69 & 14.26 \\
**Median** & 2.75 & 14.00 & 0.93 & 16.00 \\
**75 th percentile** & 5.36 & 22.38 & 1.19 & 18.52 \\ \hline \end{tabular}
\end{table} 
Table 1: Summary of patient characteristics. Figure 5: Bland\(-\)Altman plots for the ICV, BPV, and CSF, visually demonstrating the difference in measurements between the manual and SyMRI methods in relation to the mean values of both measurement methods. Figure 6: Scatter plots with fit lines and 95% confidence interval borders. Figure 7: Box plots comparing the agreements between SyMRI-derived CSF volumes with (**a**) manual measurements, and (**b**) human raters.