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 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 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.

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.

scholarly journals Evaluation of Arterial Spin Labeling MRI—Comparison with 15O-Water PET on an Integrated PET/MR Scanner

Diagnostics ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 821
Author(s):  
Markus Fahlström ◽  
Lieuwe Appel ◽  
Eva Kumlien ◽  
Torsten Danfors ◽  
Mathias Engström ◽  
...  
Keyword(s):  
Arterial Spin Labeling ◽  
Focal Epilepsy ◽  
Negative Relationship ◽  
Compartment Model ◽  
Spin Labeling ◽  
Clinical Value ◽  
Arterial Blood ◽  
Positron Emission ◽  
Continuous Arterial Spin Labeling ◽  
Subcortical Regions

Cerebral blood flow (CBF) measurements are of high clinical value and can be acquired non-invasively with no radiation exposure using pseudo-continuous arterial spin labeling (ASL). The aim of this study was to evaluate accordance in resting state CBF between ASL (CBFASL) and 15O-water positron emission tomography (PET) (CBFPET) acquired simultaneously on an integrated 3T PET/MR system. The data comprised ASL and dynamic 15O-water PET data with arterial blood sampling of eighteen subjects (eight patients with focal epilepsy and ten healthy controls, age 21 to 61 years). 15O-water PET parametric CBF images were generated using a basis function implementation of the single tissue compartment model. Cortical and subcortical regions were automatically segmented using Freesurfer. Average CBFASL and CBFPET in grey matter were 60 ± 20 and 75 ± 22 mL/100 g/min respectively, with a relatively high correlation (r = 0.78, p < 0.001). Bland-Altman analysis revealed poor agreement (bias = −15 mL/100 g/min, lower and upper limits of agreements = −16 and 45 mL/100 g/min, respectively) with a negative relationship. Accounting for the negative relationship, the width of the limits of agreement could be narrowed from 61 mL/100 g/min to 35 mL/100 g/min using regression-based limits of agreements. Although a high correlation between CBFASL and CBFPET was found, the agreement in absolute CBF values was not sufficient for ASL to be used interchangeably with 15O-water PET.

scholarly journals Non-Invasive Measurement of Choroid Plexus Blood Flow with Arterial Spin Labeling

2020 ◽  
Author(s):  
Li Zhao ◽  
Manuel Taso ◽  
Weiying Dai ◽  
Daniel Z. Press ◽  
David C. Alsop
Keyword(s):  
Blood Flow ◽  
Choroid Plexus ◽  
Gray Matter ◽  
Arterial Spin Labeling ◽  
Spin Labeling ◽  
Non Invasive ◽  
Arterial Blood ◽  
Feasible Option ◽  
Blood Flow Dynamics ◽  
Arterial Transit Time

Abstract Background The choroid plexus is a major contributor to the generation of cerebrospinal fluid (CSF) and the maintenance of its electrolyte and metabolite balance. Here, we sought to characterize the blood flow dynamics of the choroid plexus using arterial spin labeling (ASL) MRI to establish ASL as a non-invasive tool for choroid plexus function and disease studies.Methods Seven healthy volunteers were imaged on a 3T MR scanner. ASL images were acquired with 12 labeling durations and post labeling delays. Regions of the choroid plexus were manually segmented on high-resolution T1 weighted images. Choroid plexus perfusion was characterized with a dynamic ASL perfusion model. Cerebral gray matter perfusion was also quantified for comparison.Results Kinetics of the ASL signal were clearly different in the choroid plexus than in gray matter. The choroid plexus has a significantly longer T1 (2.33 ± 0.30 s vs. 1.85 ± 0.10 s, p < 0.02) and a trend of lower arterial transit time (1.24±0.20 s vs.1.31 ± 0.12 s) than the gray matter. Blood flow to the choroid plexus was measured to be 39.5 ± 10.1 ml/100 g/min and 0.80 ± 0.31 ml/min integrated over the posterior lateral ventricles in both hemispheres.Conclusions Our findings suggest that ASL can provide a clinically feasible option to quantify the dynamic characteristics of choroid plexus blood flow. It also provides useful reference values of the choroid plexus perfusion. The long T1 of the choroid plexus may suggest the transport of water from arterial blood to the CSF, potentially providing a method to quantify CSF generation.

scholarly journals Non-invasive measurement of choroid plexus apparent blood flow with arterial spin labeling

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Li Zhao ◽  
Manuel Taso ◽  
Weiying Dai ◽  
Daniel Z. Press ◽  
David C. Alsop
Keyword(s):  
Blood Flow ◽  
Choroid Plexus ◽  
Gray Matter ◽  
Arterial Spin Labeling ◽  
Spin Labeling ◽  
Non Invasive ◽  
Arterial Blood ◽  
Feasible Option ◽  
Blood Flow Dynamics ◽  
Arterial Transit Time

Abstract Background The choroid plexus is a major contributor to the generation of cerebrospinal fluid (CSF) and the maintenance of its electrolyte and metabolite balance. Here, we sought to characterize the blood flow dynamics of the choroid plexus using arterial spin labeling (ASL) MRI to establish ASL as a non-invasive tool for choroid plexus function and disease studies. Methods Seven healthy volunteers were imaged on a 3T MR scanner. ASL images were acquired with 12 labeling durations and post labeling delays. Regions of the choroid plexus were manually segmented on high-resolution T1 weighted images. Choroid plexus perfusion was characterized with a dynamic ASL perfusion model. Cerebral gray matter perfusion was also quantified for comparison. Results Kinetics of the ASL signal were clearly different in the choroid plexus than in gray matter. The choroid plexus has a significantly longer T1 than the gray matter (2.33 ± 0.30 s vs. 1.85 ± 0.10 s, p < 0.02). The arterial transit time was 1.24 ± 0.20 s at the choroid plexus. The apparent blood flow to the choroid plexus was measured to be 39.5 ± 10.1 ml/100 g/min and 0.80 ± 0.31 ml/min integrated over the posterior lateral ventricles in both hemispheres. Correction with the choroid plexus weight yielded a blood flow of 80 ml/100 g/min. Conclusions Our findings suggest that ASL can provide a clinically feasible option to quantify the dynamic characteristics of choroid plexus blood flow. It also provides useful reference values of the choroid plexus perfusion. The long T1 of the choroid plexus may suggest the transport of water from arterial blood to the CSF, potentially providing a method to quantify CSF generation.

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