Various MRS Application Tools for Alzheimer Disease and Mild Cognitive Impairment

Abstract

SUMMARY MR spectroscopy is a noninvasive technique that allows the detection of several naturally occurring compounds (metabolites) from well-defined regions of interest within the human brain. Alzheimer disease, a progressive neurodegenerative disorder, is the most common cause of dementia in the elderly. During the past 20 years, multiple studies have been performed on MR spectroscopy in patients with both mild cognitive impairment and Alzheimer disease. Generally, MR spectroscopy studies have found decreased N-acetylaspartate and increased myo-inositol in both patients with mild cognitive impairment and Alzheimer disease, with greater changes in Alzheimer disease than in mild cognitive impairment. This review summarizes the information content of proton brain MR spectroscopy and its related technical aspects, as well as applications of MR spectroscopy to mild cognitive impairment and Alzheimer disease. While MR spectroscopy may have some value in the differential diagnosis of dementias and assessing prognosis, more likely its role in the near future will be predominantly as a tool for monitoring disease response or progression in treatment trials. More work is needed to evaluate the role of MR spectroscopy as a biomarker in Alzheimer disease and its relationship to other imaging modalities.

On the early diagnosis of Alzheimer's Disease from multimodal signals: A survey

“…Furthermore, it provides a low spatial resolution. Consequently, MRS "is little used in the clinical evaluation of subjects with dementia" [164]. Furthermore, for the best of our knowledge, automatic AD diagnosis systems based on MRSI and machine learning techniques have not been reported up to date.…”

Quantitativein vivoneurochemical profiling in humans: where are we now?

“…These MRS studies report valuable observations about a variety of CNS disorders, but the range of detectable metabolites is almost completely limited only to NAA, tCr and tCho. Some recent publications of interest include reviews on Alzheimer disease and mild cognitive impairments, 51,52 common dementias, 53 psychiatric disorders, 54 autism spectrum disorders 55 and alcohol abuse disorders. 56 Recently, the MRS 63 Potential of in vivo neurochemical profiling in epidemiology…”

What can imaging tell us about cognitive impairment and dementia?

“…MRS is a technique to measure the biological metabolites in the target tissue, specifically the metabolites N-acetylaspartate (NAA), a marker of neuronal integrity, which decreases and myo-inositol, a marker of glial proliferation and neuronal damage, which increases. These changes are seen typically in the posterior cingulate gyrus, mesial temporal lobe, parieto-occipital lobes and the frontoparietal lobes [34] . Cerebral perfusion is imaged using blood…”

“…C PIB, Florbetapir 3 uptake in amyloid plaques [42] Tau specific ligands -PET, MRI-BOLD, fMRI↓connectivity in DMN, MR perfusion [38] , MR spectroscopy, DTI -↓ medial temporal lobe and precuneus [34] , VBM LBD Intracellular Lewy bodiesaggregates of α-synuclein particles in pre-synaptic terminals Overlaps with Parkinson's disease Atrophy in inferior frontal lobe, visual cortex, insula, hypothalamus, midbrain, caudate, putamen and anterior hippocampi (CA1 subregion) [86] SPECT -↓in putamen and caudate, visual cortex [88,89] FDG PET -↓in visual cortices [88][89][90] FP-CIT-↓uptake in putamen and caudate [79] Cholinergic PET/ SPECT-↓in medial occipital lobe [95] 123 I MIBG-↓cardiac uptake [96] Diffusion weighted MR-DTI, ↓ in visual association cortex and posterior putamen MRS, fMRI ASL-MR…”