Quantitative Assessment of Cerebral Hemodynamic Parameters by QUASAR Arterial Spin Labeling in Alzheimer's Disease and Cognitively Normal Elderly Adults at 3-Tesla

Article type: Research Article

Authors: Mak, Henry K.F.^{a; b; c; *} | Chan, Queenie^d | Zhang, Zhipeng^a | Petersen, Esben T.^e | Qiu, Deqiang^a | Zhang, Linda^a | Yau, Kelvin K.W.^f | Chu, Leung-Wing^{g; b; c} | Golay, Xavier^h

Affiliations: [a] Department of Diagnostic Radiology, The University of Hong Kong, HKSAR, Pokfulam, Hong Kong | [b] Alzheimer's Disease Research Network, The University of Hong Kong, HKSAR, Pokfulam, Hong Kong | [c] Research Centre of Heart, Brain, Hormone and Healthy Aging, Li Ka Shing Faculty of Medicine, The University of Hong Kong, HKSAR, Pokfulam, Hong Kong | [d] Philips Healthcare Hong Kong, HKSAR, Wanchai, Hong Kong | [e] Center of Functionally Integrative Neuroscience, Department of Neuroradiology, Aarhus University Hospital, Aarhus C, Denmark | [f] Department of Management Sciences, City University of Hong Kong, HKSAR, Pokfulam, Hong Kong | [g] University Department of Medicine, Division of Geriatric Medicine, Queen Mary Hospital, HKSAR, Pokfulam, Hong Kong | [h] Department of Brain Repair and Rehabilitation, UCL Institute of Neurology>, National Hospital for Neurology and Neurosurgery, London, United Kingdom

Correspondence: [*] Correspondence to: Henry K.F. Mak, Room 406, Block K, Queen Mary Hospital, 102 Pokfulam Road, Pokfulam, Hong Kong. Tel.: +852 22553307; Fax: +852 28174013; E-mail: makkf@hkucc.hku.hk.

Abstract: QUASAR arterial spin labeling (ASL) was used to investigate the role of vascular impairment in Alzheimer's disease (AD). We hypothesized that the hemodynamic parameters monitoring cerebrovascular integrity, i.e., cerebral blood flow (CBF), arterial blood volume (aBV), and arterial transit time (aTT), would be affected. 13 AD patients and 15 healthy control (HC) subjects underwent 3T MRI scanning. Two separate blood flow acquisitions were obtained with 1 slice overlap for whole brain coverage. CBF, aBV, and aTT maps were calculated using in-house software. Preprocessing and statistical analyses were performed on SPM5. Region-of-interest (ROI) studies of ten selected cerebral regions were also conducted. There were significant differences in Mini Mental Status Exam (MMSE) (AD: 16.3 ± 4.55, HC: 28.5 ± 2.00) and Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) scores (AD: 25.25 ± 9.64, HC: 5.51 ± 2.62) between the 2 groups (p < 0.001) but none in age (p = 0.068). CBF decreased significantly (p < 0.01) in AD compared to controls in the right middle cingulate, left cuneus, left inferior and middle frontal, right superior frontal, left inferior parietal, and right supramarginal gyri. ROI studies confirmed significant hemodynamic impairments in AD compared to HC (p < 0.05): CBF in middle and posterior cingulate, aBV in left superior temporal, right inferior parietal, and posterior cingulate, and aTT in left inferior frontal and middle cingulate gyri. CBF correlated positively while aTT correlated negatively to MMSE, and vice versa for ADAS-cog. Using QUASAR ASL, we found patterns of regional hemodynamic impairment typical of moderate AD, suggesting underlying vascular abnormality. As potential biomarkers, these hemodynamic parameters could differentiate patients from volunteers, and possibly indicate the conversion from healthy aging to mild cognitive impairment to AD.

Keywords: Alzheimer's disease, arterial blood volume, arterial spin labeling, arterial transit time, cerebral blood flow, magnetic resonance imaging, mild cognitive impairment, QUASAR

DOI: 10.3233/JAD-2012-111877

Journal: Journal of Alzheimer's Disease, vol. 31, no. 1, pp. 33-44, 2012