期刊
NEUROIMAGE-CLINICAL
卷 15, 期 -, 页码 348-358出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.nicl.2017.05.009
关键词
Calibrated fMRI; Alzheimer's disease; Cerebral blood flow; Oxidative metabolism; Oxygen extraction fraction; BOLD calibration constant; Cerebrovascular reactivity
类别
资金
- Canadian Institutes of Health Research [MOP 123492]
- Canada Foundation for Innovation [17380]
- Natural Sciences and Engineering Research Council of Canada [R0018142]
- Consortium quebecois sur la decouverte du medicament (CQDM)
Calibrated fMRI based on arterial spin-labeling (ASL) and blood oxygen-dependent contrast (BOLD), combined with periods of hypercapnia and hyperoxia, can provide information on cerebrovascular reactivity (CVR), resting blood flow (CBF), oxygen extraction fraction (OEF), and resting oxidative metabolism (CMRO2). Vascular and metabolic integrity are believed to be affected in Alzheimer's disease (AD), thus, the use of calibrated fMRI in AD may help understand the disease and monitor therapeutic responses in future clinical trials. In the present work, we applied a calibrated fMRI approach referred to as Quantitative O2 (QUO2) in a cohort of probable AD dementia and age-matched control participants. The resulting CBF, OEF and CMRO2 values fell within the range from previous studies using positron emission tomography (PET) with O-15 labeling. Moreover, the typical parietotemporal pattern of hypoperfusion and hypometabolism in AD was observed, especially in the precuneus, a particularly vulnerable region. We detected no deficit in frontal CBF, nor in whole grey matter CVR, which supports the hypothesis that the effects observed were associated specifically with AD rather than generalized vascular disease. Some key pitfalls affecting both ASL and BOLD methods were encountered, such as prolonged arterial transit times (particularly in the occipital lobe), the presence of susceptibility artifacts obscuring medial temporal regions, and the challenges associated with the hypercapnic manipulation in AD patients and elderly participants. The present results are encouraging and demonstrate the promise of calibrated fMRI measurements as potential biomarkers in AD. Although CMRO2 can be imaged with O-15 PET, the QUO2 method uses more widely available imaging infrastructure, avoids exposure to ionizing radiation, and integrates with other MRIbased measures of brain structure and function.
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