The mismatch in the spatial resolution of Arterial Spin Labeling (ASL) MRI perfusion images and the anatomy of functionally distinct tissues in the brain leads to a partial volume effect (PVE),... Show moreThe mismatch in the spatial resolution of Arterial Spin Labeling (ASL) MRI perfusion images and the anatomy of functionally distinct tissues in the brain leads to a partial volume effect (PVE), which in turn confounds the estimation of perfusion into a specific tissue of interest such as gray or white matter. This confound occurs because the image voxels contain a mixture of tissues with disparate perfusion properties, leading to estimated perfusion values that reflect primarily the volume proportions of tissues in the voxel rather than the perfusion of any particular tissue of interest within that volume. It is already recognized that PVE influences studies of brain perfusion, and that its effect might be even more evident in studies where changes in perfusion are co-incident with alterations in brain structure, such as studies involving a comparison between an atrophic patient population vs control subjects, or studies comparing subjects over a wide range of ages. However, the application of PVE correction (PVEc) is currently limited and the employed methodologies remain inconsistent. In this article, we outline the influence of PVE in ASL measurements of perfusion, explain the main principles of PVEc, and provide a critique of the current state of the art for the use of such methods. Furthermore, we examine the current use of PVEc in perfusion studies and whether there is evidence to support its wider adoption. We conclude that there is sound theoretical motivation for the use of PVEc alongside conventional, 'uncorrected', images, and encourage such combined reporting. Methods for PVEc are now available within standard neuroimaging toolboxes, which makes our recommendation straightforward to implement. However, there is still more work to be done to establish the value of PVEc as well as the efficacy and robustness of existing PVEc methods. Show less
Background and Purpose Cerebral amyloid angiopathy (CAA) is a common pathology of the leptomeningeal and cortical small vessels associated with hemorrhagic and non-hemorrhagic brain injury. Given... Show moreBackground and Purpose Cerebral amyloid angiopathy (CAA) is a common pathology of the leptomeningeal and cortical small vessels associated with hemorrhagic and non-hemorrhagic brain injury. Given previous evidence for CAA-related loss of cortical thickness and white matter volume, we hypothesized that CAA might also cause tissue loss in the basal ganglia. Methods We compared basal ganglia volumes expressed as a percentage of total intracranial volume (pBGV) of non-demented patients with sporadic and hereditary CAA to age-matched healthy control (HC) and Alzheimer's disease (AD) cohorts.Results Patients with sporadic CAA had lower pBGV (n=80, 1.16%+/- 0.14%) compared to HC (n=80, 1.30%+/- 0.13%, P<0.0001) and AD patients (n=80, 1.23%+/- 0.11%, P=0.001). Similarly, patients with hereditary CAA demonstrated lower pBGV (n=25, 1.26%+/- 0.17%) compared to their matched HC (n=25, 1.36%+/- 0.15%, P=0.036). Using a measurement of normalized basal ganglia width developed for analysis of clinical-grade magnetic resonance images, we found smaller basal ganglia width in patients with CAA-related lobar intracerebral hemorrhage (ICH; n=93, 12.35 +/- 1.47) compared to age-matched patients with hypertension-related deep ICH (n=93, 13.46 +/- 1.51, P<0.0001) or HC (n=93, 15.45 +/- 1.22, P<0.0001). Within the sporadic CAA research cohort, decreased basal ganglia volume was independently correlated with greater cortical gray matter atrophy (r=0.45, P<0.0001), increased basal ganglia fractional anisotropy (r=-0.36, P=0.001), and worse performance on language processing (r=0.35, P=0.003), but not with cognitive tests of executive function or processing speed.Conclusions These findings suggest an independent effect of CAA on basal ganglia tissue loss, indicating a novel mechanism for CAA-related brain injury and neurologic dysfunction. Show less
Kolk, A.; Zwaal, P. van der; Thomassen, B.J.W.; Kamp, E.W.C. van de; Stijnen, T.; Groot, J.H. de; Nelissen, R.G.H.H. 2018
The general objective of this thesis was to study the causes and consequences of ventricular dilatation in aging and dementia. For this purpose, we used ventricular shape analysis to study... Show moreThe general objective of this thesis was to study the causes and consequences of ventricular dilatation in aging and dementia. For this purpose, we used ventricular shape analysis to study potential new MRI markers of cognitive decline in aging, subjective memory complaints, mild cognitive impairment and Alzheimer's Disease. In addition, we designed a volumetric measure that may objectively quantify the disproportionate ventricular dilatation that is characteristic of Normal Pressure Hydrocephalus (NPH). We investigated the value of this measure for the selection of candidates with NPH for ventricular shunting, studied its association with NPH-like symptoms in the general population and used the measure to explore a possible cardiovascular origin of cerebral ventricular dilatation. Show less
