Non-ECG-gated myocardial perfusion MRI using continuous magnetization-driven radial sampling

Purpose: Establishing a high-resolution non-ECG-gated first-pass perfusion (FPP) cardiac MRI technique may improve accessibility and diagnostic capability of FPP imaging. We propose a non-ECG-gated FPP imaging technique using continuous magnetization-driven golden-angle radial acquisition. The main purpose of this preliminary study is to evaluate whether, in the simple case of single-slice two-dimensional imaging, adequate myocardial contrast can be obtained for accurate visualization of hypoperfused territories in the setting of myocardial ischemia.

Methods: A T1-weighted pulse sequence with continuous golden-angle radial sampling was developed for non-ECG-gated FPP imaging. A sliding-window scheme with no temporal acceleration was used to reconstruct 8 frames/s. Canines were imaged at 3T with and without coronary stenosis using the proposed scheme and a conventional magnetization-prepared ECG-gated FPP method.

Results: Our studies showed that the proposed non-ECG-gated method is capable of generating high-resolution (1.7 × 1.7 × 6 mm(3) ) artifact-free FPP images of a single slice at high heart rates (92 ± 21 beats/min), while matching the performance of conventional FPP imaging in terms of hypoperfused-to-normal myocardial contrast-to-noise ratio (proposed: 5.18 ± 0.70, conventional: 4.88 ± 0.43). Furthermore, the detected perfusion defect areas were consistent with the conventional FPP images.

Conclusion: Non-ECG-gated FPP imaging using optimized continuous golden-angle radial acquisition achieves desirable image quality (i.e., adequate myocardial contrast, high spatial resolution, and minimal artifacts) in the setting of ischemia.