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

Purpose: Turbulent how 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 greater than or equal to 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. (C) 1998 Elsevier Science Inc.