Correlating brain blood oxygenation level dependent (BOLD) fractal dimension mapping with magnetic resonance spectroscopy (MRS) in Alzheimer’s disease
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To correlate temporal fractal structure of resting state blood oxygen level dependent (rsBOLD) functional magnetic resonance imaging (fMRI) with in vivo proton magnetic resonance spectroscopy (1H-MRS), in Alzheimer’s disease (AD) and healthy age-matched normal controls (NC).
Materials and methods
High temporal resolution (4 Hz) rsBOLD signal and single voxel (left putamen) magnetic resonance spectroscopy data was acquired in 33 AD patients and 13 NC. The rsBOLD data was analyzed using two types of fractal dimension (FD) analysis based on relative dispersion and frequency power spectrum. Comparisons in FD were performed between AD and NC, and FD measures were correlated with 1H-MRS findings.
Temporal fractal analysis of rsBOLD, was able to differentiate AD from NC subjects (P = 0.03). Low FD correlated with markers of AD severity including decreased concentrations of N-acetyl aspartate (R = 0.44, P = 0.015) and increased myoinositol (mI) (R = −0.45, P = 0.012).
Based on these results we suggest fractal analysis of rsBOLD could provide an early marker of AD.
KeywordsFractals Magnetic resonance imaging Magnetic resonance spectroscopy
This work was supported by the Canadian Institute of Health Research (CHIR) FRN79779 (WM) and the Ontario Graduate Scholarship in Science and Technology Fund Raymond Moore Scholarship (MAW).
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