Four‐dimensional velocity mapping of the hepatic and splanchnic vasculature with radial sampling at 3 tesla: A feasibility study in portal hypertension

Abstract

Purpose To demonstrate the feasibility of PC-VIPR (Phase Contrast Vastly undersampled Imaging with Projection Reconstruction) for the depiction and hemodynamic analysis of hepatic and splanchnic vessels in patients with portal hypertension. Methods & Materials 24 cirrhotic patients (55.9±10.4years) were scanned using 5-point PC-VIPR for high spatial resolution imaging with large volume coverage at 3T using a 32-channel body coil. Vessel segmentation and hemodynamic visualization included color-coded 3D streamlines and particle traces. Segmentation quality was compared to contrast-enhanced multi-phase liver imaging. Flow pattern analysis was performed in consensus of 3 readers. The MELD score was calculated to estimate disease severity and was correlated to image quality. Results Good to excellent visualization quality was achieved in 23/24 cases. All arterial vessels and 144/168 vessels of the portal venous (PV) circulation were unambiguously identified. No correlation with the MELD score was found. 8/148 vessels of the PV circulation demonstrated reverse (hepatofugal) flow. Hepatofugal flow small tributaries to PV flow were present in three cases despite hepatopetal flow in the PV. Conclusion This feasibility study demonstrates the feasibility of PC-VIPR for simultaneous morphological and hemodynamic assessment of the hepatic and splanchnic vasculature in cirrhosis and portal hypertension. Future studies with quantitative analyses are warranted.

Vascular assessment of liver disease—towards a new frontier in MRI

“…47,60 Studies in a small cohort of patients with cirrhosis also failed to show correlation with MELD scores 61 or differences in patients with known portal hypertension. 62 …”

Emerging Applications of Abdominal 4D Flow MRI

“…For all cases presented in this article, 4D flow MRI was performed with a 5-point radially undersampled phase-contrast acquisition (i.e., phase contrast with vastly undersampled isotropic projection reconstruction) because of its increased velocity sensitivity performance [27, 28] and complete coverage of the upper abdomen [22–25]. Studies were conducted on a clinical 3-T scanner (Discovery MR750, GE Healthcare) with a 32-channel phased-array body coil (catalog number NC004000, NeoCoil).…”

“…Furthermore, a single velocity-encoding setting limits the evaluation of flow to the portal and splanchnic venous vasculature. Alternatively, 3D radial undersampling strategies have shown the feasibility of both qualitative and quantitative flow assessment of the mesenteric hemodynamics with high spatial resolution and large volumetric coverage in reasonable scanning times, on the order of 10–15 minutes [22–25]. More recently, a method combining spiral sampling with compressed sensing reconstruction introduced a major acceleration to the 4D flow MRI acquisition in a single breath-hold, although with limited spatial and temporal resolution [26].…”

Comparison of radial 4D Flow-MRI with perivascular ultrasound to quantify blood flow in the abdomen and introduction of a porcine model of pre-hepatic portal hypertension

“…Recent advances in time-resolved, three-dimensional and three-directionally velocity sensitive magnetic resonance imaging (“4D Flow-MRI”) have made the noninvasive quantification of blood flow to the entire hepatic vasculature possible [4–9]. Radial [4–6, 10, 11] and Cartesian [7–9, 12–14] data sampling schemes have been successfully applied and compared [15] to evaluate upper abdominal and hepatic blood flow.…”

“…Radial [4–6, 10, 11] and Cartesian [7–9, 12–14] data sampling schemes have been successfully applied and compared [15] to evaluate upper abdominal and hepatic blood flow. In principle, Cartesian scans have had limited volumetric coverage and are typically focused on the hepatic vessel supply including the portal vein and its proximal tributaries and branches as well as the hepatic artery [7, 9, 16].…”