An ultrasound model to calculate the brain blood outflow through collateral vessels: a pilot study

Abstract

BackgroundThe quantification of the flow returning from the head through the cervical veins and the collaterals of the internal jugular vein (IJV), is becoming of prominent interest in clinical practice. We developed a novel model to calculate the cerebral venous return, normalized to the arterial inflow, in the different segments of the IJV.MethodsWe assessed, by established Echo Colour Doppler (ECD) methodology, the head inflow (HBinF) defined as the sum of common carotids and vertebral arteries, as well as the cerebral flow (CBF) defined as the sum of internal carotid and vertebral arteries. We also assessed the head outflow (HBoutF) defined as the sum of the measurements at the junction of the IJV and the vertebral veins. In addition, we also calculated the collateral flow index (CFI) by estimating the flow which re-enters directly into the superior vena cava as the amount of blood extrapolated by the difference between the HBinF and the HBoutF. We preliminarily tested the model by comparing ten healthy controls (HC) with ten patients affected by chronic cerebral spinal venous insufficiency (CCSVI), a condition characterized by some blockages in the IJV which are bypassed by collateral circulation.ResultsIn HC the HBinF was 956+-105ml/min, whereas the HBoutF was > 90% of the HBinF, leading to a final CFI value of 1%. The last result shows that a very small amount of blood is drained by the collaterals. In upright we confirmed a reduction of the outflow through the IJV which increased CFI to 9%. When we applied the model to CCSVI, the HBinF was not significantly different from controls. In supine, the flow of CCSVI patients in the IJV junction was significantly lower (p < 0.001) while the correspondent CFI value significantly increased (61%, p < 0.0002).ConclusionsOur preliminary application of the novel model in the clinical setting suggests the pivotal role of the collateral network in draining the blood into the superior vena cava under CCSVI condition.

The Pathology of the Internal Jugular Vein Wall in Multiple Sclerosis

“…Finally, it has been shown how in MS patients the brain in-flow is not significantly different respect to controls. To the contrary, brain out-flow is significantly restricted, with increased proportion of the brain in-flow which is drained through the collaterals route [55].…”

On the consistency of flow rate color Doppler assessment for the internal jugular vein

“…[1][2][3][4]6,10 Of course this method includes a high risk of reliability loss since the TAV and CSA assessment sites could not remain the same when moving from L to T scanning plane. Aim of the present study is to evaluate different ways of CSA measurement and to identify a consistent methodology to assess the flow rate, so as to avoid the significance loss risk when moving from L to T scanning.…”

Comment on “Reproducibility of Cerebrospinal Venous Blood Flow and Vessel Anatomy with the Use of Phase Contrast–Vastly Undersampled Isotropic Projection Reconstruction and Contrast-Enhanced MRA”

“…One of our findings, also confirmed by Chambers et al, 3 is that the flow increases as blood nears the heart. 2,4 On the other hand, in Table 1 of their article, Schrauben et al 1 reported that flow slightly decreases nearing the heart, by considering the left and right IJVs both as separated or as one. It is beyond the scope of this letter to compare the potential of the 2 modalities in assessing cerebrospinal flow.…”

“…Therefore, we are working to improve the US diagnostic methodology by using indexes based on the quantification of flow in the cerebrospinal veins to extend the current qualitative approach. 2 Indeed, in our article, we proposed a simple model that, by assuming the conservation of mass criterion, allows us to work out the flow in the internal jugular veins (IJVs) and the collateral veins. One of our findings, also confirmed by Chambers et al, 3 is that the flow increases as blood nears the heart.…”