146 Chapter 7 Figure 7.1. Overview of the study procedures. 3D T1: T1-weighted MRI scan; 3D FLAIR: 3D fluid-attenuated inversion recovery SWI: susceptibilityweighted scan; DWI: diffusion weighted scan; CSF: cerebrospinal fluid selective-T2prep-REadout with Acceleration and Mobility encoding 7.4.2 Population We will prospectively include 50 outpatients over 65 years of age with memory complaints from the memory/geriatric clinic at one of their first visits, at the Leiden University Medical Center or the Alrijne hospital in Leiden. All participants give written informed consent prior to any study procedures. The current study involves 3T and 7T MRI and newly developed sequences and markers, especially for brain clearance, which have not been applied in patient populations before. Therefore, we performed the sample size calculation based on the WMH shape analysis. To provide a frame of reference we performed a sample size calculation using data from a previous manuscript.26 The linear regression performed on hypertension and convexity, corrected for age and sex, was performed with data of 71 non-demented older adults. The same WMH shape analysis pipeline was used in the previous study as we aim to use in the current study. Using the data from this significant results, the sample size calculation performed in G*Power27 showed a result of 79 participants. As the data used in the calculation was obtained from community-dwelling individuals, we expect higher effect sizes in our study consisting of a memory clinic population.
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