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

Abstract

BACKGROUND AND PURPOSE The chronic cerebrospinal venous insufficiency hypothesis raises interest in cerebrospinal venous blood flow imaging, which is more complex and less established than in arteries. For accurate assessment of venous flow in chronic cerebrospinal venous insufficiency diagnosis and research, we must account for physiologic changes in flow patterns. This study examines day-to-day flow variability in cerebrospinal veins by use of 4D MR flow and contrast-enhanced MRA under typical, uncontrolled conditions in healthy individuals. MATERIALSANDMETHODS Ten healthy volunteers were scanned in a test-retest fashion by use of a 4D flow MR imaging technique and contrast-enhanced MRA. Flow parameters obtained from phase contrast-vastly undersampled isotropic projection reconstruction and contrast-enhanced MRA scoring measurements in the head, neck, and chest veins were analyzed for internal consistency and interscan reproducibility. RESULTS Internal consistency was satisfied at the torcular herophili, with an input-output difference of 2.2%. Percentages of variations in flow were 20.3%, internal jugular vein; 20.4%, azygos vein; 6.8%, transverse sinus; and 5.1%, common carotid artery. Retrograde flow was found in the lower internal jugular vein (4.8%) and azygos vein (7.2%). Contrast-enhanced MRA interscan κ values for the internal jugular vein (left: 0.474, right: 0.366) and azygos vein (−0.053) showed poor interscan agreement. CONCLUSIONS Phase contrast–vastly undersampled isotropic projection reconstruction blood flow measurements are reliable and highly reproducible in intracranial veins and in the common carotid artery but not in veins of the neck (internal jugular vein) and chest (azygos vein) because of normal physiologic variation. Retrograde flow normally may be observed in the lower internal jugular vein and azygos vein. Low interrater agreement in contrast-enhanced MRA scans was observed. These findings have important implications for imaging diagnosis and experimental research of chronic cerebrospinal venous insufficiency.

Neurovascular 4DFlow MRI (Phase Contrast MRA): emerging clinical applications

“…4DFlow MRI has been shown to be accurate and reproducible for measuring dural sinus flow velocity, flow rate and demonstrating streamline flow in normal subjects [79]. In the sagittal sinus, blood flow velocity and blood flow rate increases from anterior to posterior as the sagittal sinus increases in size.…”

“…Small venous structures are less reliably assessed due to limitations in spatial resolution and low signal due to very slow flow. Reference values for dural sinus velocity and blood flow rates in normal subjects are available for comparison across age groups and provide a foundation for developing clinical applications [79].…”

“…Including these images would likely have reduced the number of false positives. In addition to the magnitude images, 4DFlow provides objective blood flow data that allows for qualitative and quantitative assessment of treatment related improvements in dural sinus blood flow [79].…”

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.…”

Cerebral Veins-Why Functional MR Imaging is Worth the Trouble

“…However, previous MR venography studies were hampered by their low specificity: Extracranial large veins may collapse with the patient in a supine position and consequently lead to stenosis or occlusions in MR angiography, which is physiologic and only temporary. 12,13 In the current issue of the American Journal of Neuroradiology, Schrauben et al 14 evaluate the accuracy and reproducibility of blood flow analysis by using MR imaging in both intra-and extracranial veins in 10 healthy volunteers. They used both contrast-enhanced MR angiography and 3D phase-contrast MR imaging with 3D velocity-encoding.…”