Reliability and Reproducibility of Hadamard Encoded Pseudo-Continuous Arterial Spin Labeling in Healthy Elderly.

Katja Neumann,Matthias Günther,Tony Stöcker,Martin Schidlowski,Emrah Düzel

doi:10.3389/fnins.2021.711898

Abstract

The perfusion parameters cerebral blood flow (CBF) and arterial transit time (ATT) measured with arterial spin labeling (ASL) magnetic resonance imaging (MRI) provide valuable essentials to assess the integrity of cerebral tissue. Brain perfusion changes, due to aging, an intervention, or neurodegenerative diseases for example, could be investigated in longitudinal ASL studies with reliable ASL sequences. Generally, pseudo-continuous ASL (pCASL) is preferred because of its larger signal-to-noise ratio (SNR) compared to pulsed ASL (PASL) techniques. Available pCASL versions differ regarding their feature details. To date only little is known about the reliability and reproducibility of CBF and ATT measures obtained with the innovative Hadamard encoded pCASL variant, especially if applied on participants in old age. Therefore, we investigated an in-house developed Hadamard encoded pCASL sequence on a group of healthy elderly at two different 3 Tesla Siemens MRI systems (Skyra and mMR Biograph) and evaluated CBF and ATT reliability and reproducibility for several regions-of-interests (ROI). Calculated within-subject coefficients of variation (wsCV) demonstrated an excellent reliability of perfusion measures, whereas ATT appeared to be even more reliable than CBF [e.g., wsCV(CBF) = 2.9% vs. wsCV(ATT) = 2.3% for a gray matter (GM) ROI on Skyra system]. Additionally, a substantial agreement of perfusion values acquired on both MRI systems with an inter-session interval of 78 ± 17.6 days was shown by high corresponding intra-class correlation (ICC) coefficients [e.g., ICC(CBF) = 0.704 and ICC(ATT) = 0.754 for a GM ROI]. The usability of this novel Hadamard encoded pCASL sequence might improve future follow-up perfusion studies of the aging and/or diseased brain.

Highlights

Arterial Spin Labeling (ASL) is a magnetic resonance imaging (MRI) technique that provides insights to microvascular brain perfusion (Williams et al, 1992)
An analysis of the variance (ANOVA) showed that the overall translation in y-direction during the first run of the pseudocontinuous ASL (pCASL) scan was significantly less if acquired at the Skyra system
We investigated the cerebral perfusion obtained with a 7block Hadamard encoded 3D pCASL sequence on a group of healthy elderly at two different 3T Siemens MR systems (Skyra, mMR Biograph)

Summary

Introduction

Arterial Spin Labeling (ASL) is a magnetic resonance imaging (MRI) technique that provides insights to microvascular brain perfusion (Williams et al, 1992). CBF gives the volume of blood [in unit (ml)] being delivered to a certain mass of tissue (usually 100 g is used) during a given time period (e.g., 1 min). This results in the common unit (ml/100 g/min) for CBF. The spatial structure of the cerebral vasculature reflects the respective demand of oxygen and nutrients in gray and white matter tissue and its need to adapt appropriately to changing conditions. This explains why the ATT for gray matter is usually lower than for white matter. An accurate measure of the ATT is valuable for a correct CBF quantification

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Conclusion