Longitudinal Changes in Cerebral Blood Flow Calculated by Arterial Spin Labeling MRI in Parkinson’s Disease
Dilek Betul Arslan1, Sevim Cengiz1, Kardelen Eryurek2, Ozan Genc1, Ani Kicik2, Emel Erdogdu2,3, Zeynep Tufekcioglu4, Basar Bilgic4, Hasmet Hanagasi4, Aziz Mufit Ulug1, Ibrahim Hakan Gurvit4, Tamer Demiralp2,5, and Esin Ozturk-Isik1

1Biomedical Engineering Institute, Bogazici University, Istanbul, Turkey, 2Hulusi Behcet Life Sciences Research Center, Istanbul University, Istanbul, Turkey, 3Institute of Psychology and Cognition Research, University of Bremen, Bremen, Germany, 4Department of Neurology, Istanbul University, Istanbul, Turkey, 5Department of Physiology, Istanbul University, Istanbul, Turkey


The aim of this study is to monitor perfusion changes over one and a half years in Parkinson’s disease with mild cognitive impairment (PD-MCI). Cerebral blood flow (CBF) maps were created for baseline and follow-up scans by fitting a kinetic curve model for each pixel of arterial spin labeling MR images. The CBF maps were registered to MNI152 brain atlas, and perfusion changes were assessed at 119 distinct brain regions. The CBF of PD-MCI patients decreased at occipital fusiform gyrus, right occipital fusiform gyrus, anterior part of left supramarginal gyrus, and anterior part of right middle temporal gyrus over time.


Mild cognitive impairment in Parkinson’s disease (PD-MCI) is an intermediate stage between cognitively normal PD (PD-CN) and dementia (PDD). PD-MCI patients have an increased risk of developing dementia.1 Previous studies have reported that abnormal perfusion patterns could provide information about the diagnosis of cognitive decline in PD.2,4 Arterial spin labeling MRI (ASL-MRI) provides information about perfusion parameters by measuring cerebral blood flow (CBF).5 The main aim of this study is to quantify the longitudinal change in perfusion measurements of PD-MCI patients.


23 PD-MCI patients, who were previously diagnosed based on an extensive neuropsychological test battery, were included in this study. All participants were scanned on a 3T Philips MR scanner with a 32-channel head coil after they received their medications to reduce motion artifacts. ASL-MR images were obtained from six slices at eight different inversion times (TIs) by using STAR labeling with Look-Locker readout. For each slice, data acquisition was repeated 30 times to increase signal to noise (SNR). Also, acquisition was repeated three times to cover the whole brain. Follow-up analysis was carried out after one and a half years, and the patients were scanned by employing the same ASL-MRI sequence. A program was written in MATLAB R2018a (MathWorks Inc., Natick, MA) to calculate the CBF maps. The main magnetization, M0, was calculated for each pixel of control images by fitting multiple TI data to the longitudinal relaxation equation by taking into account the flip angle effect. CBF maps were calculated by using the combination of the model proposed by Gunther et al. 6 and the correction of arterial blood volume proposed by Chappell et al 7. CBF maps were registered into MNI152 brain atlas by using FMRIB Software Library (FSL) (http://fsl.fmrib.ox.ac.uk/fsl/fslwiki/). CBF values were estimated at 119 distinct brain regions defined by Harvard-Oxford cortical and subcortical structural atlases and the MNI structural atlas. A Wilcoxon signed-rank test was used to assess the CBF changes over time. A P-value of less than 0.05 was considered as statistically significant.


Figure 1 shows CBF maps calculated for one PD-MCI subject at baseline (a) and follow-up (b) time points. Based on neuropsychological test assessments, five PD-MCI patients converted from MCI to CN, while the status of 18 PD-MCI patients didn’t change. Table 1 shows the mean (+std) CBF values of 18 PD-MCI patients at the brain regions that had a change over time. At follow-up, PD-MCI patients had lower perfusion at occipital fusiform gyrus, right occipital fusiform gyrus, anterior part of left supramarginal gyrus and anterior part of right middle temporal gyrus compared to baseline measurements. There were not any statistically significant differences between baseline and follow-up CBF values of the patients who converted to CN.


In line with our study results, previous studies have reported hypoperfusion primarily at the parieto-occipital areas for PD.2-4 Right anterior temporal gyrus has been correlated with visual recognition scores.8 The supramarginal gyrus, which is a portion of the parietal lobe, has a role in visual word recognition.9 The progressive perfusion decrease might be related to visual deficits of PD.


In conclusion, CBF values measured by ASL-MRI might help in monitoring the progression of PD-MCI, and might be useful for providing a biomarker for the cognitive assessment of Parkinson’s disease. In future, CBF values will be assessed at brain parcellations obtained from resting state fMRI.10 Partial volume correction will be applied in ASL data analysis to compare pure gray matter perfusion values of subjects.11


This study was supported by TUBITAK project #115S219 and the Ministry of Development project #2010K120330.


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Figure 1. The CBF maps of one example PD-MCI patient at baseline (a) and follow up (b) time points.

Table 1. Regions indicating a statistically significant difference between follow-up and baseline CBF values and P values calculated by a Wilcoxon signed-rank test.

Proc. Intl. Soc. Mag. Reson. Med. 27 (2019)