Low dose gadobenate dimeglumine for imaging of chronic myocardial infarction in comparison with standard dose gadopentetate dimeglumine.

OBJECTIVES: Gadobenate dimeglumine has a 2-fold higher T1 relaxivity compared with gadopentetate dimeglumine and can be used for imaging delayed enhancement in the assessment of myocardial infarction. The purpose of this study was to compare 0.1 mmoL/kg gadobenate dimeglumine (Gd-BOPTA, MultiHance, Bracco Imaging SpA, Milan, Italy) with 0.2 mmoL/kg gadopentetate dimeglumine (Gd-DTPA, Magnevist, Bayer-Schering Pharma AG, Berlin, Germany) in cardiac magnetic resonance imaging.
MATERIALS AND METHODS: The study was performed in accordance with the institutional review board. Two groups of 20 patients underwent magnetic resonance examinations for evaluation of chronic myocardial infarction. Although group 1 received gadobenate dimeglumine at a dose of 0.1 mmoL/kg, group 2 received gadopentetate dimeglumine at a dose of 0.2 mmoL/kg. Single shot inversion recovery (IR) steady-state free precession (SSFP), and IR gradient echo sequence (GRE) sequences were used for imaging delayed enhancement. The sizes of myocardial infarctions were measured for both contrast agents in both imaging techniques by 2 readers. Bland-Altman analyses were performed for each sequence and gadolinium chelate. Furthermore, the transmural extent of myocardial infarction was assessed by 2 readers according to the 17-segment model for both contrast media and both sequences and kappa values were calculated. Signal-to-noise ratios for infarcted myocardium, normal myocardium, and the left ventricular cavity were measured, and the contrast-to-noise ratios of infarcted compared with normal myocardium (CNRinf-myo) and infarcted myocardium in relation to the left ventricular cavities (CNRinf-LVC) were calculated.
RESULTS: The Bland-Altman plots in the assessment of infarction size did not reveal a systematic bias between the 2 readers. The mean difference between reader 1 and 2 was less than 0.9 cm3 of mean infarction volume. Assessment of interobserver agreement regarding the transmural extent of myocardial infarction resulted in kappa values of kappa = 0.845 (IR SSFP) and kappa = 0.874 (IR GRE) in gadobenate-enhanced images and kappa = 0.841 (IR SSFP) and kappa = 0.833 (IR GRE) after administration of gadopentetate. CNRinf-normal was significantly higher on the images of group 1 (gadobenate) compared with group 2 (gadopentetate) in both sequences (single shot IR SSFP: 18.1 +/- 10.1 vs. 12.1 +/- 6.7; P = 0.032 and IR GRE: 27.2 +/- 5.8 vs. 19.7 +/- 5.9; P = 0.005). The mean value of CNRinf-LVC for the group examined with Gd-BOPTA was lower, though not significantly, compared with the group examined with Gd-DTPA in IR GRE technique, whereas CNRinf-LVC for IR SSFP resulted in equal values (single shot IR SSFP: 1.2 +/- 5.2 vs. 1.1 +/- 6.8; P = n.s. and IR GRE 2.4 +/- 5.8 vs. 5.8 +/- 7.9; P = n.s.).
CONCLUSIONS: Low dose Gd-BOPTA resulted in significantly higher CNRinf-myo compared with standard dose Gd-DTPA in imaging of myocardial infarction with IR SSFP and IR GRE sequences. Demarcation of infarcted myocardium from the left ventricular cavity assessed by CNR showed no significant difference after application of either contrast media in both imaging techniques.