E011 Measurement of caudate and putamen volume at 3-Tesla and 7-Tesla MRI: a direct comparison using data from the Huntington’s disease young adult study (HD-YAS)

<h3>Background</h3> Brain measures derived from MRI have contributed to our understanding of Huntington’s disease (HD) pathology and are now being implemented as biomarkers for clinical trials. 3T is the standard field strength used but 7T scanning is increasingly available. 7T has known benefits over 3T, such as improved resolution and contrast; however, it is also susceptible to artefacts. In HD, increasing field strength may improve accuracy of region-of-interest measurements, such as the caudate and putamen, and hence improve detectability and localisation of subtle disease-related changes. However, this has not been directly examined before. <h3>Aims</h3> 1)To compare volume measurements of the caudate and putamen at 3T and 7T MRI. 2) To examine the strength of correlations between these 3T- and 7T-derived volumes and other biomarkers, such as neurofilament light. 3)To determine if the HD-Integrated Staging System ratings can be accurately derived from 7T MRI. <h3>Methods</h3> HD-YAS contains a subset of participants who underwent scanning at both 3T and 7T (18 gene expansion carriers and 20 age- and gender-matched controls). 3T MPRAGE data and 7T MP2RAGE data were processed using FreeSurfer versions 6.0.1 and 7.2.0. Preprocessing methods were additionally investigated to facilitate 7T data analysis, such as denoising using SPM12. Outputs from FreeSurfer were carefully visually inspected for accurate delineation of regions-of-interest, and volumes were extracted. <h3>Results</h3> All 3T scans ran successfully in FreeSurfer and all caudate and putamen regions passed quality control. Analysis of the 7T data is ongoing. We will present findings in line with the aforementioned aims.