scholarly journals Optimization and Reliability of Multiple Postlabeling Delay Pseudo-Continuous Arterial Spin Labeling during Rest and Stimulus-Induced Functional Task Activation

2014 ◽  
Vol 34 (12) ◽  
pp. 1919-1927 ◽  
Author(s):  
Melvin Mezue ◽  
Andrew R Segerdahl ◽  
Thomas W Okell ◽  
Michael A Chappell ◽  
Michael E Kelly ◽  
...  
Keyword(s):  
Arterial Spin Labeling ◽  
Motor Task ◽  
Region Of Interest ◽  
High Sensitivity ◽  
Spin Labeling ◽  
Brain Regions ◽  
Experimental Investigations ◽  
Good Test ◽  
Arterial Blood ◽  
Functional Task

Arterial spin labeling (ASL) sequences that incorporate multiple postlabeling delay (PLD) times allow estimation of when arterial blood signal arrives within a region of interest. Sequences that account for such variability may improve the reliability of ASL and therefore make the technique well suited for future clinical and experimental investigations of cerebral perfusion. This study assessed the within- and between-session reproducibility of an optimized pseudo-continuous ASL (pCASL) functional magnetic resonance imaging (FMRI) sequence that incorporates multiple postlabeling delays (multi-PLD pCASL). Healthy subjects underwent four identical scans separated by 30 minutes, 1 week, and 1 month using multi-PLD pCASL to image absolute perfusion (cerebral blood flow (CBF) and arterial arrival time (AAT)) during both rest and a visual-cued motor task. We show good test-retest reliability, with strong consistency across subjects and sessions during rest (inter-session within-subject coefficient of variation: gray matter (GM) CBF = 6.44%; GM AAT = 2.20%). We also report high sensitivity and reproducibility during the functional task, where we show robust task-related decreases in AAT corresponding with regions of increased CBF. Importantly, these results give insight into optimal PLD selection for future investigations using single-PLD ASL to image different brain regions, and highlight the necessity of multi-PLD ASL when imaging perfusion in the whole brain.

scholarly journals Dual-Echo Arterial Spin Labeling for Brain Perfusion Quantification and Functional Analysis

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
André Monteiro Paschoal ◽  
Fernando Fernandes Paiva ◽  
Renata Ferranti Leoni
Keyword(s):  
Arterial Spin Labeling ◽  
Pulse Sequence ◽  
Brain Connectivity ◽  
Motor Task ◽  
Brain Perfusion ◽  
Spin Labeling ◽  
Blood Oxygenation ◽  
Specific Response ◽  
Bivariate Correlation ◽  
Dual Echo

Arterial Spin Labeling (ASL) is a noninvasive MRI-based method to measure cerebral blood flow (CBF). Recently, the study of ASL as a functional tool has emerged once CBF fluctuation comes from capillaries in brain tissue, giving a more spatially specific response when compared to the standard functional MRI method, based on the blood oxygenation level-dependent (BOLD) contrast. Although the BOLD effect could be desirable to study brain function, if one aims to quantify CBF, such effect is considered contamination that can be more attenuated if short TE value is used in the image acquisition. An approach that provides both CBF and function information in a simultaneous acquisition is the use of a dual-echo ASL (DE-ASL) readout. Our purpose was to evaluate the information provided by DE-ASL regarding CBF quantification and functional connectivity with a motor task. Pseudocontinuous ASL of twenty healthy subjects (age: 32.4 ± 10.2 years, 13 male) was acquired at a 3T scanner. We analyzed the influence of TE on CBF values and brain connectivity provided by CBF and concurrent BOLD (cc-BOLD) time series. Brain networks were obtained by the general linear model and independent component analysis. Connectivity matrices were generated using a bivariate correlation (Fisher Z values). No effect of the sequence readout, but significant effect of the TE value, was observed on gray matter CBF values. Motor networks with reduced extension and more connections with important regions for brain integration were observed for CBF data acquired with short TE, proving its higher spatial specificity. Therefore, it was possible to use a dual-echo readout provided by a standard commercial ASL pulse sequence to obtain reliable quantitative CBF values and functional information simultaneously.

scholarly journals Comparison of cerebral blood flow measurement with [15O]-water positron emission tomography and arterial spin labeling magnetic resonance imaging: A systematic review

2016 ◽  
Vol 36 (5) ◽  
pp. 842-861 ◽  
Author(s):  
Audrey P Fan ◽  
Hesamoddin Jahanian ◽  
Samantha J Holdsworth ◽  
Greg Zaharchuk
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Arterial Spin Labeling ◽  
Brain Perfusion ◽  
Spin Labeling ◽  
Emission Tomography ◽  
Flow Measurements ◽  
Arterial Blood ◽  
Positron Emission

Noninvasive imaging of cerebral blood flow provides critical information to understand normal brain physiology as well as to identify and manage patients with neurological disorders. To date, the reference standard for cerebral blood flow measurements is considered to be positron emission tomography using injection of the [15O]-water radiotracer. Although [15O]-water has been used to study brain perfusion under normal and pathological conditions, it is not widely used in clinical settings due to the need for an on-site cyclotron, the invasive nature of arterial blood sampling, and experimental complexity. As an alternative, arterial spin labeling is a promising magnetic resonance imaging technique that magnetically labels arterial blood as it flows into the brain to map cerebral blood flow. As arterial spin labeling becomes more widely adopted in research and clinical settings, efforts have sought to standardize the method and validate its cerebral blood flow values against positron emission tomography-based cerebral blood flow measurements. The purpose of this work is to critically review studies that performed both [15O]-water positron emission tomography and arterial spin labeling to measure brain perfusion, with the aim of better understanding the accuracy and reproducibility of arterial spin labeling relative to the positron emission tomography reference standard.

scholarly journals Noninvasive Assessment of Arterial Compliance of Human Cerebral Arteries with Short Inversion Time Arterial Spin Labeling

2015 ◽  
Vol 35 (3) ◽  
pp. 461-468 ◽  
Author(s):  
Esther AH Warnert ◽  
Kevin Murphy ◽  
Judith E Hall ◽  
Richard G Wise
Keyword(s):  
Arterial Spin Labeling ◽  
Arterial Input Function ◽  
Arterial Compliance ◽  
Cerebral Arteries ◽  
Spin Labeling ◽  
Input Function ◽  
Inversion Time ◽  
Arterial Blood ◽  
Left Posterior ◽  
Middle Cerebral Arteries

A noninvasive method of assessing cerebral arterial compliance (AC) is introduced in which arterial spin labeling (ASL) is used to measure changes in arterial blood volume (aBV) occurring within the cardiac cycle. Short inversion time pulsed ASL (PASL) was performed in healthy volunteers with inversion times ranging from 250 to 850 ms. A model of the arterial input function was used to obtain the cerebral aBV. Results indicate that aBV depends on the cardiac phase of the arteries in the imaging volume. Cerebral AC, estimated from aBV and brachial blood pressure measured noninvasively in systole and diastole, was assessed in the flow territories of the basal cerebral arteries originating from the circle of Willis: right and left middle cerebral arteries (RMCA and LMCA), right and left posterior cerebral arteries (RPCA and LPCA), and the anterior cerebral artery (ACA). Group average AC values calculated for the RMCA, LMCA, ACA, RPCA, and LPCA were 0.56%±0.2%, 0.50%±0.3%, 0.4%±0.2%, 1.1%±0.5%, and 1.1%±0.3% per mm Hg, respectively. The current experiment has shown the feasibility of measuring AC of cerebral arteries with short inversion time PASL.

scholarly journals Improved calculation of the equilibrium magnetization of arterial blood in arterial spin labeling

2018 ◽  
Vol 80 (5) ◽  
pp. 2223-2231 ◽  
Author(s):  
André Ahlgren ◽  
Ronnie Wirestam ◽  
Linda Knutsson ◽  
Esben Thade Petersen
Keyword(s):  
Arterial Spin Labeling ◽  
Spin Labeling ◽  
Arterial Blood ◽  
Equilibrium Magnetization

scholarly journals Arterial spin labeling perfusion: Prospective MR imaging in differentiating neoplastic from non-neoplastic intra-axial brain lesions

2018 ◽  
Vol 31 (6) ◽  
pp. 544-553 ◽  
Author(s):  
Neetu Soni ◽  
Karthika Srindharan ◽  
Sunil Kumar ◽  
Prabhakar Mishra ◽  
Girish Bathla ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Arterial Spin Labeling ◽  
Region Of Interest ◽  
Spin Labeling ◽  
Brain Lesions ◽  
Cutoff Value ◽  
Magnetic Resonance Perfusion ◽  
Perilesional Edema ◽  
Clinical Magnetic Resonance Imaging ◽  
Neoplastic Lesions

Purpose The purpose of this article is to assess the diagnostic performance of arterial spin-labeling (ASL) magnetic resonance perfusion imaging to differentiate neoplastic from non-neoplastic brain lesions. Material and methods This prospective study included 60 consecutive, newly diagnosed, untreated patients with intra-axial lesions with perilesional edema (PE) who underwent clinical magnetic resonance imaging including ASL sequences at 3T. Region of interest analysis was performed to obtain mean cerebral blood flow (CBF) values from lesion (L), PE and normal contralateral white matter (CWM). Normalized (n) CBF ratio was obtained by dividing the mean CBF value of L and PE by mean CBF value of CWM. Discriminant analyses were performed to determine the best cutoff value of nCBFL and nCBFPE in differentiating neoplastic from non-neoplastic lesions. Results Thirty patients were in the neoplastic group (15 high-grade gliomas (HGGs), 15 metastases) and 30 in the non-neoplastic group (12 tuberculomas, 10 neurocysticercosis, four abscesses, two fungal granulomas and two tumefactive demyelination) based on final histopathology and clincoradiological diagnosis. We found higher nCBFL (6.65 ± 4.07 vs 1.68 ± 0.80, p < 0.001) and nCBFPE (1.86 ± 1.43 vs 0.74 ± 0.21, p < 0.001) values in the neoplastic group than non-neoplastic. For predicting neoplastic lesions, we found an nCBFL cutoff value of 1.89 (AUC 0.917; 95% CI 0.854 to 0.980; sensitivity 90%; specificity 73%) and nCBFPE value of 0.76 (AUC 0.783; 95% CI 0.675 to 0.891; sensitivity 80%; specificity 58%). Mean nCBFL was higher in HGGs (8.70 ± 4.16) compared to tuberculomas (1.98 ± 0.87); and nCBFPE was higher in HGGs (3.06 ± 1.53) compared to metastases (0.86 ± 0.34) and tuberculomas (0.73 ± 0.22) ( p < 0.001). Conclusion ASL perfusion may help in distinguishing neoplastic from non-neoplastic brain lesions.

Calibration: Estimating Arterial Blood Magnetization

2017 ◽  
Author(s):  
Michael Chappell ◽  
Bradley MacIntosh ◽  
Thomas Okell
Keyword(s):  
Arterial Spin Labeling ◽  
Spin Labeling ◽  
Calibration Factor ◽  
Perfusion Mri ◽  
Reference Region ◽  
Arterial Blood ◽  
Mri Measurements ◽  
Calibration Step

To get a measure of perfusion in absolute units from arterial spin labeling (ASL) perfusion MRI measurements, a further calibration step is required. Using a separate image acquired at the same time as the main ASL data, a number of options exist to calculate the required value of arterial blood magnetization. This chapter outlines common approaches, along with their differing strengths and weaknesses, including using a reference region of tissue, or computation of the necessary calibration factor in each voxel of the image.

Quantification of Perfusion Changes during a Motor Task Using Arterial Spin Labeling

2011 ◽  
Vol 24 (1) ◽  
pp. 85-91 ◽  
Author(s):  
P. Vilela ◽  
M. Pimentel ◽  
I. Sousa ◽  
P. Figueiredo
Keyword(s):  
Arterial Spin Labeling ◽  
Motor Task ◽  
Spin Labeling

scholarly journals Multivariate and Univariate Analysis of Continuous Arterial Spin Labeling Perfusion MRI in Alzheimer's Disease

2007 ◽  
Vol 28 (4) ◽  
pp. 725-736 ◽  
Author(s):  
Iris Asllani ◽  
Christian Habeck ◽  
Nikolaos Scarmeas ◽  
Ajna Borogovac ◽  
Truman R Brown ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Multivariate Analysis ◽  
Arterial Spin Labeling ◽  
Spin Echo ◽  
Univariate Analysis ◽  
Region Of Interest ◽  
Spin Labeling ◽  
Planar Imaging ◽  
Continuous Arterial Spin Labeling

Continuous arterial spin labeling (CASL) magnetic resonance imaging (MRI) was combined with multivariate analysis for detection of an Alzheimer's disease (AD)-related cerebral blood flow (CBF) covariance pattern. Whole-brain resting CBF maps were obtained using spin echo, echo planar imaging (SE-EPI) CASL in patients with mild AD ( n=12, age=70.7±8.7 years, 7 males, modified Mini-Mental State Examination (mMMS)=38.7/57±11.1) and age-matched healthy controls (HC) ( n=20; age=72.1±6.5 years, 8 males). A covariance pattern for which the mean expression was significantly higher ( P<0.0005) in AD than in HC was identified containing posterior cingulate, superior temporal, parahippocampal, and fusiform gyri, as well as thalamus, insula, and hippocampus. The results from this analysis were supplemented with those from the more standard, region of interest (ROI) and voxelwise, univariate techniques. All ROIs (17/hemisphere) showed significant decrease in CBF in AD ( P<0.001 for all ROIs, αcorrected=0.05). The area under the ROC curve for discriminating AD versus HC was 0.97 and 0.94 for covariance pattern and gray matter ROI, respectively. Fewer areas of depressed CBF in AD were detected using voxelwise analysis (corrected, P<0.05). These areas were superior temporal, cingulate, middle temporal, fusiform gyri, as well as inferior parietal lobule and precuneus. When tested on extensive split-half analysis to map out the replicability of both multivariate and univariate approaches, the expression of the pattern from multivariate analysis was superior to that of the univariate.

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