In vitro model of arterial stenosis: correlation of MR signal dephasing and trans-stenotic pressure gradients.

Overview

PURPOSE: Turbulent flow just distal to stenoses causes signal loss (dephasing) on magnetic resonance angiography (MRA). This study correlates dephasing with trans-stenotic pressure gradients in an in vitro model of arterial stenosis. MATERIALS AND METHODS: Three-dimensional (3D) phase contrast, 2D time-of-flight, and 3D spoiled gradient echo MRA with/without gadolinium and varied echo time were performed for a system consisting of a peristaltic perfusion pump and a silastic vessel with stenoses of varying caliber. Length and diameter of dephasing jets were measured, and volumes calculated at varying pressure gradients and echo times, then correlated with percentage cross-sectional area stenosis as measured by conventional angiography. RESULTS: Dephasing occurred in all sequences at pressure gradients of > or =4 mmHg (1 mmHg = 133 Pa) and stenoses of greater than 70%, and varied directly with pressure gradient. The dephasing was greatest for 3D phase contrast (PC). Gadolinium did not diminish dephasing. CONCLUSIONS: MRA signal dephasing at stenoses varies directly with pressure gradient. MRA may provide a non-invasive means for determining the hemodynamic significance of arterial stenoses.