Materials and Methods: Nine mongrel dogs were subjected to whole-heart coronary MRA in 2 separate sessions at 7-day intervals with a 3 T scanner using the FLASH sequence with either gadoterate meglumine (Gd-DOTA) or the ESPIO (KEG3). Coronary MRA was performed twice at each MR examination: the first scan during the administration of the contrast agent and the subsequent second scan at 15 minutes after contrast injection. Objective measurements of the Gd-DOTA and ESPIO images, including the signal-to-noise ratios (SNRs) for the coronary arteries and cardiac veins, contrast-to-noise ratios (CNRs) between the vessels and fat (CNRfat) and the vessels and the myocardium (CNRmyocardium), and subjective image quality scores on a 4-point scale were evaluated and compared.
Results: The mean SNRs and CNRs of all vascular regions in the ESPIO images were similar to those of the corresponding regions in the Gd-DOTA images in the first scan (98.1 +/- 32.5 vs 79.1 +/- 38.4 for SNR of coronary arteries, P = 0.3; 74.2 +/- 30.1 vs 61.4 +/- 38.5 for CNR, P = 0.7) and more than 2 times higher than the latter in the second scan (95.2 +/- 31.3 vs 32.1 +/- 8.1 for SNR of coronary arteries, P = 0.008; 76.1 +/- 35.8 vs 17.6 +/- 19.2 for CNR, P 0.008). Similarly, the mean values of the subjective measurements of the ESPIO images were similar to those of the Gd-DOTA images (3.9 +/- 0.3 vs 3.3 +/- 0.8 for coronary arteries, P = 0.1) in the first scan and significantly better than the latter in the second scan (3.9 +/- 0.2 vs 2.1 +/- 0.6 for coronary arteries, P = 0.007).
Conclusions: The experimental blood pool agent KEG3 offers equivalent image quality for whole-heart coronary MRA at 3 T upon contrast administration and persistent better quality in the subsequent scans, compared with a traditional extracellular gadolinium-based contrast agent.
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