Neuroimaging in Dementia

Abstract

OBJECTIVE: Neurodegenerative diseases are significant health concerns with regard to morbidity and social and economic hardship around the world. This review describes the state of the field of neuroimaging measures as biomarkers for detection and diagnosis of both slowly progressing and rapidly progressing neurodegenerative diseases, specifically Alzheimer disease, vascular cognitive impairment, dementia with Lewy bodies or Parkinson disease dementia, frontotemporal lobar degeneration spectrum disorders, and prion-related diseases. It briefly discusses findings in these diseases in studies using MRI and metabolic and molecular-based imaging (eg, positron emission tomography [PET] and single-photon emission computerized tomography [SPECT]).LATEST DEVELOPMENTS: Neuroimaging studies with MRI and PET have demonstrated differential patterns of brain atrophy and hypometabolism in different neurodegenerative disorders, which can be useful in differential diagnoses. Advanced MRI sequences, such as diffusion-based imaging, and functional MRI (fMRI) provide important information about underlying biological changes in dementia and new directions for development of novel measures for future clinical use. Finally, advancements in molecular imaging allow clinicians and researchers to visualize dementia-related proteinopathies and neurotransmitter levels.ESSENTIAL POINTS: Diagnosis of neurodegenerative diseases is primarily based on symptomatology, although the development of in vivo neuroimaging and fluid biomarkers is changing the scope of clinical diagnosis, as well as the research into these devastating diseases. This article will help inform the reader about the current state of neuroimaging in neurodegenerative diseases, as well as how these tools might be used for differential diagnoses.

Preserving cognitive function in patients with Alzheimer's disease: The Alzheimer's disease neuroprotection research initiative (ADNRI)

“…This enables us to study metabolic alterations associated with AD progression 14 . One of the most valuable MRI modalities in AD is resting‐state functional MRI, which has been used to show how AD impairs multiple functional networks across the brain, including the default mode network, the salience network, or the dorsal attention network 11 …”

“…Nuclear medicine imaging techniques are extremely sensitive and can detect AD biomarkers at very early stages. PET is the gold standard technique for tau and Aβ‐specific imaging as well as for visualizing glucose metabolism in the brain 11 . Interestingly, PET has been used to show that tau may propagate along functional networks, instead of disseminating locally, but that this is not the case for amyloid 15 .…”

“…Its noninvasiveness, image quality (in terms of image resolution and contrast generation), and multimodality allow detailed brain imaging at structural, vascular, metabolic, and functional levels. 9 In the field of AD, MRI is used to assess changes in brain structure, allowing the study of brain atrophy, 10 detecting events that may explain nondegenerative cognitive impairment, 11 and providing information about the integrity of white matter and neuronal circuits through all variants of diffusion‐weighted imaging (e.g., diffusion‐weighted imaging, diffusion tension imaging, diffusion kurtosis imaging, fiber tracking, neurite orientation dispersion, and density imaging, soma and neurite density imaging, etc. 12 ).…”

Evaluation of 3‐dimensional stereotactic surface projection rendering of arterial spin labeling data in a clinical cohort

“…Intracranial PET and SPECT imaging provides information regarding brain metabolic activity and the cerebral perfusion coupled to it 6,9,21–26 . Like ASL, the evaluation of intracranial PET and SPECT imaging and the comparison of PET and SPECT findings between subjects are challenging due to regional anatomic variations in the size and stereotactic location of brain parenchymal structures.…”

“…Intracranial PET and SPECT imaging provides information regarding brain metabolic activity and the cerebral perfusion coupled to it. 6,9,[21][22][23][24][25][26] Like ASL, the evaluation of intracranial PET and SPECT imaging and the comparison of PET and SPECT findings between subjects are challenging due to regional anatomic variations in the size and stereotactic location of brain parenchymal structures. In the field of nuclear medicine, these radiological challenges have been addressed by the incorporation of various automated 3-dimensional surfacerendered/projected visualization as typically produced by statistical parametric mapping.…”