4D flow MRI for non-invasive measurement of blood flow in the brain: A systematic review

Abstract

The brain’s vasculature is essential for brain health and its dysfunction contributes to the onset and development of many dementias and neurological disorders. While numerous in vivo imaging techniques exist to investigate cerebral haemodynamics in humans, phase-contrast magnetic resonance imaging (MRI) has emerged as a reliable, non-invasive method of quantifying blood flow within intracranial vessels. In recent years, an advanced form of this method, known as 4D flow, has been developed and utilised in patient studies, where its ability to capture complex blood flow dynamics within any major vessel across the acquired volume has proved effective in collecting large amounts of information in a single scan. While extremely promising as a method of examining the vascular system’s role in brain-related diseases, the collection of 4D data can be time-consuming, meaning data quality has to be traded off against the acquisition time. Here, we review the available literature to examine 4D flow’s capabilities in assessing physiological and pathological features of the cerebrovascular system. Emerging techniques such as dynamic velocity-encoding and advanced undersampling methods, combined with increasingly high-field MRI scanners, are likely to bring 4D flow to the forefront of cerebrovascular imaging studies in the years to come.

Cerebrovascular Reactivity Measurement Using Magnetic Resonance Imaging: A Systematic Review

“…However, calibrated fMRI models depend on the initialisation values of model parameters, model assumptions such as the oxygen metabolism not being altered during hypercapnia and hyperoxia stimuli (Germuska and Wise, 2019), and are more complex to implement. PC-MRI (12/235, 5%) measures CVR at the large-vessel level and generally provides limited spatial coverage; although 4D phasecontrast flow imaging (Miller et al, 2019;Morgan et al, 2020) is developing rapidly, the long scan duration currently limits applicability for measuring CVR in patients. Several different paradigms were used, which varied in duration and number of repetitions.…”

Cerebral arterial pulsatility is linked to hippocampal microvascular function and episodic memory in healthy older adults

“…In 4D flow MRI (3D PC), velocities are encoded in all three spatial directions simultaneously, time-resolved over the cardiac cycle and with full brain coverage. [25][26][27][28] Previously, we have shown that by sampling and averaging flow waveforms from numerous arterial cross sections in a 4D flow MRI volume, a whole-brain representation of the cardiac related waveform can be obtained in small, distal cerebral arteries. 29 Here, we use high-resolution 4D flow MRI to examine cerebral arterial hemodynamics in a populationbased cohort of healthy older adults.…”

Hemodynamic Disturbances in Posterior Circulation Stroke: 4D Flow Magnetic Resonance Imaging Added to Computed Tomography Angiography

“…A development of 2D PCMRI is 4D flow MRI ( Gu et al, 2005 ; Morgan et al, 2020 ). It provides the ability to simultaneously measure blood flow rates in all major arteries following a single acquisition ( Strater et al, 2018 ).…”