148 Chapter 7 habits, using an adapted version of the Pittsburg Sleep Quality Index.28 The sleep questionnaire is included, because of the influence of sleep on the glymphatic system. The following tests are included in the neuropsychiatric assessment: • Mini-mental state examination29 • Clock drawing30 • 15-Word Verbal Learning Test (immediate and delayed)31 • Visual Association Test32 • Stroop Color Word Test, 40 item version33 • Trail Making Test A&B34,35 • Letter Digit Substitution Test36 • Animal fluency test37 • Hospital anxiety and depression scale38 • Informant Questionnaire on Cognitive Decline in the Elderly39 7.4.4 MRI scans All MRI scans are performed at the LUMC using a 3T Philips Ingenia Elition and a 7T Philips Achieva MRI scanner (Philips Healthcare). The MRI scan protocols are shown in table 7.1. Conventional (3T) brain MRI scans will be used to determine global and functional markers of cerebral SVD, like WMH volume and presence of lacunes, microbleeds and superficial siderosis (on a 3D T1-weighted (3D T1), 3D fluid-attenuated inversion recovery (3D FLAIR), susceptibility-weighted imaging (SWI), and a diffusion weighted imaging (DWI) scan), hemodynamics (flow territory mapping;40). Furthermore, white matter structural integrity will be measured with a MR fingerprinting sequence41 and an inhomogeneous magnetization transfer (ihMT) scan42. An fMRI scan technique will be used to measure CSF fluctuations in the 4th ventricle as a measure of brain clearance43. Ultra-high field (7T) brain MRI scans will be used to determine WMH shape (solidity, convexity, concavity index, fractal dimension, and eccentricity) and other markers of cerebral SVD in or surrounding the WMH, like enlarged perivascular spaces, (cortical) microinfarcts and microbleeds (on a T1-, T2-, FLAIR, and a T2*-weighted scan). Examples of WMH segmentations and the shape markers are shown in figures 7.2 and 7.3. Moreover, a recently implemented MRI technique called CSF-STREAM (CSFselective-T2prepared REadout with Acceleration and Mobility encoding) will be used to measure CSF-mobility in perivascular spaces, as a proxy of glymphatic activity44. An example of measurements obtained with this technique can be seen in figure 7.4.
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