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

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.

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

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x16636393 ◽

2016 ◽

Vol 36 (5) ◽

pp. 842-861 ◽

Cited By ~ 60

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.

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Reliability of two-dimensional and three-dimensional pseudo-continuous arterial spin labeling perfusion MRI in elderly populations: Comparison with 15o-water positron emission tomography

Journal of Magnetic Resonance Imaging ◽

10.1002/jmri.24246 ◽

2013 ◽

Vol 39 (4) ◽

pp. 931-939 ◽

Cited By ~ 46

Author(s):

Emily Kilroy ◽

Liana Apostolova ◽

Collin Liu ◽

Lirong Yan ◽

John Ringman ◽

...

Keyword(s):

Positron Emission Tomography ◽

Arterial Spin Labeling ◽

Three Dimensional ◽

Spin Labeling ◽

Perfusion Mri ◽

Emission Tomography ◽

Two Dimensional ◽

Positron Emission ◽

Elderly Populations ◽

Continuous Arterial Spin Labeling

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Spatial coefficient of variation in pseudo-continuous arterial spin labeling cerebral blood flow images as a hemodynamic measure for cerebrovascular steno-occlusive disease: A comparative 15O positron emission tomography study

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x18781667 ◽

2018 ◽

Vol 39 (1) ◽

pp. 173-181 ◽

Cited By ~ 6

Author(s):

Masanobu Ibaraki ◽

Kazuhiro Nakamura ◽

Hideto Toyoshima ◽

Kazuhiro Takahashi ◽

Keisuke Matsubara ◽

...

Keyword(s):

Positron Emission Tomography ◽

Blood Flow ◽

Cerebral Blood Flow ◽

Coefficient Of Variation ◽

Arterial Spin Labeling ◽

Cerebral Perfusion ◽

Spin Labeling ◽

Emission Tomography ◽

Positron Emission ◽

Continuous Arterial Spin Labeling

Pseudo-continuous arterial spin labeling (pCASL) is a completely non-invasive method of cerebral perfusion measurement. However, cerebral blood flow (CBF) quantification is hampered by arterial transit artifacts characterized by bright vascular signals surrounded by decreased signals in tissue regions, which commonly appear in patients with reduced cerebral perfusion pressure. The spatial coefficient of variation (CoV) of pCASL CBF images has been proposed as an alternative region-of-interest (ROI)-based hemodynamic measure to predict prolonged arterial transit time (ATT). This retrospective study investigates the utility of spatial CoV by comparison with 15O positron emission tomography (PET). For patients with cerebrovascular steno-occlusive disease ( n = 17), spatial CoV was positively correlated with ATT independently measured by pulsed arterial spin labeling ( r = 0.597, p < 0.001), confirming its role as an ATT-like hemodynamic measure. Comparisons with 15O PET demonstrated that spatial CoV was positively correlated with vascular mean transit time ( r = 0.587, p < 0.001) and negatively correlated with both resting CBF ( r = −0.541, p = 0.001) and CBF response to hypercapnia ( r = −0.373, p = 0.030). ROI-based spatial CoV calculated from single time-point pCASL can potentially detect subtle perfusion abnormalities in clinical settings.

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