Nine de Planque

45 Using a new technique of ASL | Trigonocephaly images in ASL processing when not available. For that reason, more advanced analysis that uses T2-weighted and DTI MR brain images to aid segmentation is planned. Moreover, we aim to study the GM CBF after partial volume correction. However, currently, tissue segmentation from T1w images is not possible for all subjects, which is a hurdle for use of partial-volume correction on an individual basis.4 Second, while this cohort of 36 preoperative MRI scans of trigonocephaly patients is limited in size, it is the first study on automated ASL evaluation in trigonocephaly patients aged 0–3 years. The craniofacial unit of the Erasmus MC continues with the prospective collection of preoperative MRI scans of craniosynostosis patients for clinical and research perspectives which includes also other patients than those with trigonocephaly. A validation of this methodology on a larger cohort is thus planned, which will also include patients with more severe skull deformations. A third limitation is that our control group consisted of patients who underwent MRI examination for clinical reasons, where the MRI and clinical course showed no cerebral pathology. At last, patients and controls were not age exactly matched. While this might slightly affect the CBF difference and the performance of the normalization between groups, the key findings of this study lie in comparing normalization methods within each group for which this minor age difference bears no importance. CONCLUSION In conclusion, when the conventional T1w and T2w contrast between GM and WM are hard to differentiate, spatial normalization is feasible by using the ASL perfusion contrast directly. The choice of contrast for registration has an impact on both the quality of ASL alignment and the extracted regional CBF values. The results of this study may be an important step toward the feasibility of future large pediatric ASL MRI brain studies. 2

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