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DOI: 10.1101/2023.05.24.23289773

Choroid Plexus Volume in Multiple Sclerosis can be estimated on structural MRI avoiding contrast injection

V.Visani F. B. Pizzini V. Natale ...+3 M. Castellaro
Background: Choroid Plexus (ChP) manual segmentation performance evaluation on non-contrast-enhanced MRI sequences compared to the gold-standard contrast-enhanced T1-w has never been done on a relevant cohort of subjects. Purpose: To investigate whether contrast-enhancing can be avoided when performing ChP manual segmentation. To select which non-contrast-enhanced sequence between T1-w and FLAIR could be used as a contrast-enhanced T1-w surrogate. To provide a quantification of the ChP volume error that non-contrast-enhanced sequences introduce. Materials and methods: Sixty-one prospective Multiple Sclerosis patients were included in the study. ChP was separately segmented on T1-w, FLAIR, and contrast-enhanced T1-w sequences. Quantitative contrast metrics between the ChP and surrounding ventricles were calculated. Quantitative segmentation metrics were obtained using gold-standard segmentation as reference. To assess the spatial agreement between non-contrast-enhanced and contrast-enhanced sequences, the segmentations were non-linearly coregistered to the standard MNI152 space and the error distribution per slice was evaluated spanning axially and coronally. Results: Concerning contrast metrics, ANOVA test revealed a statistically significant main effect between the sequences (pvalue<0.01). The post-hoc t-tests revealed higher Contrast-to-Noise-Ratio and Signal-to-Noise-Ratio for contrast-enhanced sequences than others. T1-w exhibits the lower Contrast-to-Noise-Ratio while Signal-to-Noise-Ratio was comparable between FLAIR and T1-w (mean Signal-to-Noise-Ratio/Contrast-to-Noise-Ratio: contrast-enhanced T1-w=23.77/18.49, T1-w=13.73/7.44, FLAIR=13.09/10.77). The segmentation metrics revealed that non-contrast-enhanced sequences had comparable Dice. FLAIR overestimated the ChP volume while T1-w introduced a lower bias (Percentage Volume Difference FLAIR:28.02 {+/-} 19.02%; T1-w:3.52 {+/-} 12.61%). The spatial variability analysis confirmed that ChP volume depiction presents spatial differences between segmentations. FLAIR generally underperformed T1-w. Conclusion: The quantitative analyses suggest that T1-w might be a good candidate as a surrogate of contrast-enhanced sequence for the ChP manual segmentation task to estimate ChP volume. On the contrary, FLAIR introduces a systematic overestimation bias.