Neuroimaging in vascular cognitive impairment: a state-of-the-art review

Abstract

Imaging is critical in the diagnosis and treatment of dementia, particularly in vascular cognitive impairment, due to the visualization of ischemic and hemorrhagic injury of gray and white matter. Magnetic resonance imaging (MRI) and positron emission tomography (PET) provide structural and functional information. Clinical MRI is both generally available and versatile – T2-weighted images show infarcts, FLAIR shows white matter changes and lacunar infarcts, and susceptibility-weighted images reveal microbleeds. Diffusion MRI adds another dimension by showing graded damage to white matter, making it more sensitive to white matter injury than FLAIR. Regions of neuroinflammatory disruption of the blood–brain barrier with increased permeability can be quantified and visualized with dynamic contrast-enhanced MRI. PET shows metabolism of glucose and accumulation of amyloid and tau, which is useful in showing abnormal metabolism in Alzheimer’s disease. Combining MRI and PET allows identification of patients with mixed dementia, with MRI showing white matter injury and PET demonstrating regional impairment of glucose metabolism and deposition of amyloid. Excellent anatomical detail can be observed with 7.0-Tesla MRI. Imaging is the optimal method to follow the effect of treatments since changes in MRI scans are seen prior to those in cognition. This review describes the role of various imaging modalities in the diagnosis and treatment of vascular cognitive impairment.

Stroke and dementia risk: A systematic review and meta‐analysis

“…Clear and comprehensive reporting of information related to ethnic breakdown and educational level will facilitate harmonization of these potential modifiers across studies and subsequently strengthen future meta-regression analyses. Only three studies used neuroimaging to define stroke status, and it is possible that techniques such as T2-weighted and FLAIR magnetic resonance imaging (MRI), and 18 F-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) [73] may help to reduce unexplained between-study variability by improving the quantification of stroke-related pathology which in turn increases dementia risk. Similarly, unassessed variance in participant characteristics and the incidence of dementia unrelated to stroke may also have contributed to between-study variability.…”

Imaging Morphologic Substrates and Molecular Changes for Differential Diagnosis of Vascular Dementia

“…As these studies provide insight in early changes of the diseases, selective PETstudies might be useful to detect preclinical stages in which therapeutic efforts might be promising. Multimodal imaging including advanced techniques for morphological and molecular imaging are important for research in dementias, but are also more and more introduced into clinical application [43][44][45].…”

Current Pathogenetic Concepts of Vascular Cognitive Impairment

“…Small vessel lesions which are seen by modern neuroimaging methods (particularly 7-Tesla MRI) [28] f) Cerebral microbleeds (CMBs), involving both cortex and white matter, as detected by MRI [28], are caused by hypertensive SVD and CAA [34]. Cortical microbleeds are often associated with CAA, whereas subcortical ones are mainly related to SVD or embolies, but both subcortical SVD and CAA interact to increase the risk or lobar CMBs [35].…”

“…Modern neuroimaging together with clinical and biological marker studies will continue to play a leading role in the diagnosis of dementias, in particular a more clear delineation between VCI/VaD, AD, and mixed pathology [26,28]. However, neuropathology still remains the "gold standard" of diagnosis.…”