Objectives: To compare 0.15 mmol/kg gadobutrol with 0.20 mmol/kg gadopentetate dimeglumine with regard to late gadolinium enhancement (LGE) of infarcted myocardium at magnetic resonance (MR) imaging.
Materials and methods: Twenty patients with history of chronic myocardial infarction underwent 2 cardiac MR examinations at 1.5 Tesla. For the evaluation of myocardial infarction, late gadolinium enhancement (LGE) imaging was performed with an inversion recovery-prepared gradient-echo sequence 15 minutes after administration of either gadobutrol (r1 = 5.2 mmol(-1)s(-1)) or gadopentetate dimeglumine (r1 = 4.1 mmol(-1)s(-1)). The dose of the contrast agents was adjusted based on the relaxivity of both contrast agents. Hence, gadobutrol and gadopentetate dimeglumine were administered at 0.15 mmol/kg and 0.20 mmol/kg, respectively. Contrast-to-noise ratios (CNR) between infarcted myocardium and remote myocardium (CNR remote) and between infarcted myocardium and left ventricular lumen (CNR lumen) were assessed by 2 independent readers. Additionally, infarct size was assessed semiautomatically by using a threshold of 5 standard deviations above the mean signal intensity of remote myocardium.
Results: Subendocardial or transmural LGE was present in 16 of 20 (80%) patients. The optimal inversion time for LGE imaging did not differ significantly between gadobutrol and gadopentetate dimeglumine (275 ± 21 milliseconds [range, 240-320 milliseconds] and 282 ± 23 milliseconds [range, 240-330 milliseconds], respectively; P = 0.32). The CNR remote after administration of gadobutrol (40.0 ± 4.6; 95% confidence interval [CI]: 30.3; 49.7) and gadopentetate dimeglumine (40.6 ± 4.6; 95% CI: 30.9; 50.3) did not show significant differences (P = 0.90), whereas gadobutrol yielded a significantly higher CNR lumen (6.2 ± 3.6; 95% CI: -1.5; 13.9) compared with gadopentetate dimeglumine (0.8 ± 3.6; 95% CI: -6.9; 8.5). Infarct size after administration of gadobutrol (23.7 ± 4.7 mL; 95% CI: 13.6; 33.7) and gadopentetate dimeglumine (23.7 ± 4.7 mL;95% CI: 13.7; 33.8) was not statistically different (P = 0.94). There was an excellent correlation between gadobutrol- and gadopentetate dimeglumine-enhanced assessment of infarct size (Spearman r = 0.99 and r = 0.97 for reader 1 and 2, respectively).
Conclusion: This pilot study shows that 0.15 mmol/kg gadobutrol is an effective contrast agent for LGE imaging with better delineation of infarcted myocardium from left ventricular lumen than 0.20 mmol/kg gadopentetate dimeglumine.