Oscillating dual-equilibrium steady state angiography using magnetic resonance imaging

Abstract

A method of oscillating dual-equilibrium steady-state angiography (ODESSA), utilizes a modified steady state free precession (SSFP) pulse sequence. The SSFP sequence is modified such that flowing material reaches a steady state which oscillates between two equilibrium values, while stationary material attains a standard, non-oscillatory steady state. When alternating sequences are employed, subtraction of adjacent echoes results in large, uniform signal from all flowing spins and zero signal from stationary spins. Venous signal can be suppressed based on its reduced T2. ODESSA arterial signal is more than three times as large as that of traditional phase-contrast angiography (PCA) in the same scan time, and also compares favorably with other techniques of MR angiography. Pulse sequences are implemented in 2D, 3D, and volumetric projection modes. Angiograms of the lower leg, generated in as few as 5 s, show high arterial SNR and full suppression of other tissues.

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