Intraindividual comparison of T1 relaxation times after gadobutrol and Gd-DTPA administration for cardiac late enhancement imaging

Abstract

PurposeTo evaluate T1-relaxation times of chronic myocardial infarction (CMI) using gadobutrol and gadopentetate dimeglumine (Gd-DTPA) over time and to determine the optimal imaging window for late enhancement imaging with both contrast agents. Material and methodsTwelve patients with CMI were prospectively included and examined on a 1.5T magnetic resonance (MR) system using relaxivity-adjusted doses of gadobutrol (0.15mmol/kg) and Gd-DTPA (0.2mmol/kg) in random order. T1-relaxation times of remote myocardium (RM), infarcted myocardium (IM), and left ventricular cavity (LVC) were assessed from short-axis TI scout imaging using the Look–Locker approach and compared intraindividually using a Wilcoxon paired signed-rank test (α<0.05). ResultsWithin 3min of contrast agent administration (CA), IM showed significantly lower T1-relaxation times than RM with both contrast agents, indicating beginning cardiac late enhancement. Differences between gadobutrol and Gd-DTPA in T1-relaxation times of IM and RM were statistically not significant through all time points. However, gadobutrol led to significantly higher T1-relaxation times of LVC than Gd-DTPA from 6 to 9min (220±15ms vs. 195±30ms p<0.01) onwards, resulting in a significantly greater ΔT1 of IM to LVC at 9–12min (−20±35ms vs. 0±35ms, p<0.05) and 12–15min (−25±45ms vs. −10±60ms, p<0.05). Using Gd-DTPA, comparable ΔT1 values were reached only after 25–35min. ConclusionThis study indicates good delineation of IM to RM with both contrast agents as early as 3min after administration. However, we found significant differences in T1 relaxation times with greater ΔT1 IM–LVC using 0.15mmol/kg gadobutrol compared to 0.20mmol/kg Gd-DTPA after 9–15min post-CA suggesting earlier differentiability of IM and LVC using gadobutrol.