Self-Gated Late Gadolinium Enhancement at 7T to Image Rats with Reperfused Acute Myocardial Infarction

Objective: A failed electrocardiography (ECG)-trigger often leads to a long acquisition time (TA) and deterioration in image quality. The purpose of this study was to evaluate and optimize the technique of self-gated (SG) cardiovascular magnetic resonance (CMR) for cardiac late gadolinium enhancement (LGE) imaging of rats with myocardial infarction/reperfusion. Materials and Methods: Cardiovascular magnetic resonance images of 10 rats were obtained using SG-LGE or ECG with respiration double-gating (ECG-RESP-gating) method at 7T to compare differences in image interference and TA between the two methods. A variety of flip angles (FA: 10 degrees-80 degrees) and the number of repetitions (NR: 40, 80, 150, and 300) were investigated to determine optimal scan parameters of SG-LGE technique based on image quality score and contrast-to-noise ratio (CNR). Results: Self-gated late gadolinium enhancement allowed successful scan in 10 (100%) rats. However, only 4 (40%) rats were successfully scanned with the ECG-RESP-gating method. TAs with SG-LGE varied depending on NR used (TA: 41, 82, 154, and 307 seconds, corresponding to NR of 40, 80, 150, and 300, respectively). For the ECG-RESP-gating method, the average TA was 220 seconds. For SG-LGE images, CNR (42.5 +/- 5.5, 43.5 +/- 7.5, 54 +/- 9, 59.5 +/- 8.5, 56 +/- 13, 54 +/- 8, and 41 +/- 9) and image quality score (1.85 +/- 0.75, 2.20 +/- 0.83, 2.85 +/- 0.37, 3.85 +/- 0.52, 2.8 +/- 0.51, 2.45 +/- 0.76, and 1.95 +/- 0.60) were achieved with different FAs (10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, and 40 degrees, respectively). Optimal FAs of 20 degrees-30 degrees and NR of 80 were recommended. Conclusion: Self-gated technique can improve image quality of LGE without irregular ECG or respiration gating. Therefore, SG-LGE can be used an alternative method of ECG-RESP-gating.