Fast magnetization-driven preparation for imaging of contrast-enhanced coronary arteries during intra-arterial injection of contrast agent

Purpose: To implement a short-duration magnetization preparation sequence, which consists of a saturation followed by multiple inversion pulses, for imaging of short-T₁ species and suppression of long-T₁ species. Materials and Methods: Computer optimizations were performed to derive preparation schemes that 1) suppress long-T₁ background species with T₁ > 250 msec, 2) maximize the M_z of contrast-enhanced (CE) structures with T₁ ≤ 50 msec, and 3) have a preparation duration in the range of 200 msec. The optimized sequences were tested on a phantom and a pig model instrumented with an intracoronary catheter for infusion of contrast media. Results: Computer simulations generated preparation schemes with durations of 165-225 msec depending on the number of preparation pulses used, which generated saturation of over 98% for T₁ > 250 msec, and about a 30% reduction for 20 msec < T₁ < 50 msec. The phantom studies validated the performance of the optimized sequences. Coronary artery angiograms (380 msec for preparation and image acquisition) demonstrated signal-to-noise ratios (SNRs) in the range of 13-15.5 and contrast-to-noise ratios (CNRs) in the range of 6.3-7.1 in the CE coronary vessels. Conclusion: This work demonstrates that fast magnetization-driven preparation schemes can be implemented for fast imaging of CE coronary vessels with efficient saturation of background species.