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Positron emission tomography–guided magnetic resonance spectroscopy in Alzheimer disease
Author(s) -
SheikhBahaei Nasim,
Sajjadi S. Ahmad,
Manavaki Roido,
McLean Mary,
O'Brien John T.,
Gillard Jonathan H.
Publication year - 2018
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.25202
Subject(s) - pittsburgh compound b , positron emission tomography , nuclear medicine , magnetic resonance imaging , standardized uptake value , creatine , choline , medicine , alzheimer's disease , fluorodeoxyglucose , nuclear magnetic resonance , pathology , disease , radiology , physics
Objective To determine whether the level of metabolites in magnetic resonance spectroscopy (MRS) is a representative marker of underlying pathological changes identified in positron emission tomographic (PET) images in Alzheimer disease (AD). Methods We performed PET‐guided MRS in cases of probable AD, mild cognitive impairment (MCI), and healthy controls (HC). All participants were imaged by 11 C‐Pittsburgh compound B ( 11 C‐PiB) and 18 F‐fluorodeoxyglucose ( 18 F‐FDG) PET followed by 3T MRS. PET images were assessed both visually and using standardized uptake value ratios (SUVRs). MRS voxels were placed in regions with maximum abnormality on amyloid (Aβ+) and FDG (hypometabolic) areas on PET scans. Corresponding normal areas were selected in controls. The ratios of total N‐acetyl (tNA) group, myoinositol (mI), choline, and glutamate + glutamine over creatine (Cr) were compared between these regions. Results Aβ + regions had significantly higher ( p = 0.02) mI/Cr and lower tNA/Cr ( p = 0.02), whereas in hypometabolic areas only tNA/Cr was reduced ( p = 0.003). Multiple regression analysis adjusting for sex, age, and education showed mI/Cr was only associated with 11 C‐PiB SUVR ( p < 0.0001). tNA/Cr, however, was associated with both PiB ( p = 0.0003) and 18 F‐FDG SUVR ( p = 0.006). The level of mI/Cr was not significantly different between MCI and AD ( p = 0.28), but tNA/Cr showed significant decline from HC to MCI to AD ( p = 0.001, p = 0.04). Interpretation mI/Cr has significant temporal and spatial associations with Aβ and could potentially be considered as a disease state biomarker. tNA is an indicator of early neurodegenerative changes and might have a role as disease stage biomarker and also as a valuable surrogate marker for treatment response. Ann Neurol 2018;83:771–778