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

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.