The manifestation of vortical and secondary flow in the cerebral venous outflow tract: An in vivo MR velocimetry study

Abstract

Aberrations in flow in the cerebral venous outflow tract (CVOT) have been implicated as the cause of several pathologic conditions including idiopathic intracranial hypertension (IIH), multiple sclerosis (MS), and pulsatile tinnitus (PT). The advent of 4D Flow magnetic resonance imaging (4D-Flow MRI) has recently allowed researchers to evaluate blood flow patterns in the arterial structures with great success. We utilized similar imaging techniques and found several distinct flow characteristics in the CVOT of subjects with and without lumenal irregularities. We present the flow patterns of 8 out of 38 subjects who have varying heights of the internal jugular bulb and varying lumenal irregularities including stenosis and diverticulum. In the internal jugular vein (IJV) with an elevated jugular bulb (JB), 4DFlow MRI revealed a characteristic spiral flow that was dependent on the level of JB elevation. Vortical flow was also observed in the diverticula of the venous sinuses and IJV. The diversity of flow complexity in the CVOT illustrates the potential importance of hemodynamic investigations in elucidating venous pathologies.

Jugular Anomalies in Multiple Sclerosis Are Associated with Increased Collateral Venous Flow

“…Advanced MR techniques such as 4D flow can successfully capture the spiral/vortexed flow property at the jugular bulb in persons with and without luminal irregularities 34 . In a recent study, application of a 4D flow technique combined with 3D contrast-enhanced MRA and Doppler ultrasound was used to evaluate venous structure and function in MS and other neurological diseases.…”

“…While these findings are discordant with ours, the study suffers from two notable drawbacks: the low intra-observer agreement using 3D MRA to assess venous stenosis, as well as the large age ranges used in their group comparisons yielding high variability in the flow estimates. Although 4D flow MRI enables diverse velocity-field-based analyses, it is limited by low spatial and temporal resolution, systematic errors and noise, as well as inability to resolve instantaneous and small-scale velocities 34 . Further improvements in reliability and validity of this promising approach are needed before these discrepancies can be resolved.…”

Flow patterns in the jugular veins of pulsatile tinnitus patients

“…This study was motivated by our preliminary observations of complex flow within the jugular vein (Acevedo-Bolton et al, 2015; Kefayati et al, 2016). Those studies reveal a pronounced vortex core surrounded by a peripheral circulating flow pattern.…”

“…MR velocimetry overcomes this limitation through its ability to define the full velocity vector in three-dimensional space throughout the pulsatile cycle – a method referred to as 4D MR Velocimetry (4D-MRV) (Markl et al, 2012; Nayak et al, 2015). 4D-MRV has been explored in application to the cerebral venous sinuses for both in vivo and in vitro models (Acevedo-Bolton et al, 2015, Kefayati et al, 2016). However, 4D-MRV is restricted in both spatial and temporal resolution.…”

Brain Venous Blood Outflow

“…Bolstered by this landmark paper, the simultaneous study of pressure and flow can broaden the horizons in brain fluid dynamics. It is complex and intellectually challenging, but with an advent of 4D PCMRI [9] it may increase understanding of many neurological diseases.…”