Late gadolinium enhancement magnetic resonance imaging for the assessment of myocardial infarction: comparison of image quality between single and double doses of contrast agents

To compare the image quality of late gadolinium enhancement (LGE) cardiac magnetic resonance imaging (CMR) using a single dose of gadolinium contrast agent versus the conventional double dose for assessing myocardial infarction. This retrospective study examined 37 patients with chronic myocardial infarction who underwent LGE CMR using both inversion recovery (IR)-turbo fast low-angle shot magnitude-reconstructed and phase-sensitive images with two different dosages of gadolinium contrast agent: a single dose of 0.1 mmol/kg gadolinium-DTPA in 17 patients and a double dose of 0.2 mmol/kg in 20 patients. The contrast-to-noise ratio (CNR) and visual conspicuity between infarct and normal myocardium (CNR_{infarct-normal}, conspicuity_{infarct-normal}) and between infarct and left ventricular cavity (CNR_infarct-LVC, conspicuity_infarct-LVC) were compared. Interobserver agreement for the maximal transmural extent of infarction was also evaluated. CNR_{infarct-normal} was significantly higher with double-dose gadolinium contrast agent (15.5 ± 20.7 vs. 40.4 ± 16.1 in magnitude images and 9.5 ± 2.8 vs. 11.2 ± 2.7 in phase-sensitive images, P < 0.001) while conspicuity_{infarct-normal} showed no significant difference between the two groups (P > 0.05). Both CNR_infarct-LVC (7.7 ± 10.7 vs. −6.6 ± 19.0 in magnitude images and 4.1 ± 2.3 vs. −0.4 ± 4.1 in phase-sensitive images, P < 0.05) and conspicuity_infarct-LVC were significantly better with single-dose gadolinium contrast. Interobserver agreement for assessing the transmural extent of infarction was moderate in both groups: 0.591 for single-dose and 0.472 for double-dose. LGE CMR using a single dose of gadolinium contrast agent showed significantly better contrast between infarcted myocardium and left ventricular cavity lumen without a significant decrease in visual contrast between infarcted myocardium and normal myocardium, compared to a double dose.