# Reliability of Automated Intracranial Volume Measurements by Synthetic Brain MRI in Children
## 4 Discussion
cases involving older children or adolescents, it might be an option to repeat the MDME sequence in cases of motion artifacts. It should not go unmentioned that there are also freely available alternatives for the technically experienced radiological technological or radiologist [4; 15; 20; 22]. Some of these tools were also used as reference measurement methods in this work. A decisive disadvantage in clinical routine is the increased effort involved in such manual or semi-automated evaluations. Integration into existing PACS environments, ease of use, and the automated generation of volumetric data on the respective examined neurocranium are assumed advantages of the analysed commercial software solution [3]. A synthetic MRI is based on data acquisition relying on absolute measurements of T1, T2, PD, or their respective inverse relaxation rates (R1 and R2), while also taking into account magnetic field inhomogeneity, thus making it a robust input for tissue segmentation  
Figure 11: (**a**–c) SyMRI maps depicting the erroneous segmentation of the intracranial compartments in the posterior fossa on the right side. The cause of the distortions is the magnetic valve of a ventriculo-peritoneal shunt. Figure 12: Sample slices of an MDME sequence degraded by motion artifacts in a patient that underwent a “feed and wrap” MRI of the brain. Due to image quality constraints, the SyMRI software could not perform a sufficient automatic evaluation. (**a**) MDME images; (**b**) corresponding field maps. overall [26; 27]. Initially, the lengthy duration of the data acquisition period made its implementation into the clinical workflow impractical. However, this issue was resolved with the introduction of a QRAPMASTER pulse sequence capable of simultaneously measuring the R1, R2, and PD with an exam duration under 6 min for full head coverage [37 ]. One of the significant advantages of SyMRI over conventional MRI is its wide applicability and adjustability. Quantification maps can be tailored to additionally measure tissue properties specific to particular types of lesions. Such highly specific synthetic sequences can even outperform conventional MRI in lesion detection sensitivity in some diseases [3]. A promising example is its use case of detecting plaque lesions in multiple sclerosis. Studies have shown that SyMRI performs better than conventional MRI in lesion detection, with comparable or shorter acquisition times. The time required for segmentation was also considerably lower than when using segmentation algorithms such as FSL on conventional MRI images [26; 27]. Another promising example was demonstrated by [PERSON] et al., who showed better lesion detection in brain tumors using synthetic T1 inversion recovery (T1 IR), surpassing conventional T1 IR-weighted images and providing superior lesion-to-white matter contrast and a contrast-to-noise ratio [29]. The synthetic T1- and T2-weighted images proved to have comparable or higher contrast than conventional images but also tended to suffer from higher levels of noise. Synthetic sequences are generally believed to offer comparable to inferior quality at times, even though some authors suggest that this fact does not directly translate to being inferior in clinical practice and even suggest that the agreement with clinical presentation is higher in synthetic MRI. The quality, however, is not the same for all synthetic sequences across the board; for instance, synthetic T2-weighted FLAIR images have shown to have both lower contrast and higher signal noise, resulting in a generally inferior contrast-to-noise ratio against conventional FLAIR images [30]. Our study, however, did not directly focus on a qualitative comparison of synthetic sequences against conventional ones; therefore, we are unable to provide more detailed assessment of the usefulness of SyMRI in this regard as it was used as a supplement alongside a routine workflow to deliver volumetric assessments exclusively. Neonatal MR imaging volumetry has demonstrated its prognostic value in different studies [31; 32; 33].