Objectives The aim of this study was to evaluate the feasibility and accuracy of free-breathing three-dimensional (3D) phase-sensitive inversion-recovery (PSIR) Turbo FLASH sequence for noninvasive assessment of left ventricular myocardial scar in swine.
Methods Nine Chinese minipigs with experimentally induced acute myocardial infarction (MI) were studied. At 1 week and the study endpoint 4 weeks after MI surgery, the 3D and 2D LGE imaging were performed randomly by using a 1.5T clinical MR imaging system. Comparisons of myocardial scar volume (in cubic centimetres), scar transmurality (on a 5 points scale) and image quality (on a 4 points Likert scale) were performed by using the Pearson correlation and Bland-Altman analysis (for myocardial scar volume) or κ statistics (for transmurality) or Wilcoxon signed rank test (for image quality).
Results In 6 of the 9 pigs, all procedures were successfully completed. In these pigs, a total of 26 segments with myocardial scars were detected by both 3D and 2D sequences, and there was good agreement for classification of scar transmurality (κ = 0.930). The scar volume determined by TTC staining (3.52 ± 1.40 cm3) showed a good correlation with both 3D (3.54 ± 1.36 cm3, r = 0.957, p = 0.003) and 2D sequence (3.53 ± 1.26 cm3, r = 0.942, p = 0.005) at 4 weeks. And there were good correlation between scar volumes obtained from 3D and 2D techniques (r = 0.859, p < 0.001) at both time points. Both 3D and 2D images detected a small reduction of scar volume from week 1 to week 4 by a factor of 1.179 and 1.176, respectively. Although a little more artefacts were observed on 2D PSIR images, the overall image quality was not significantly different between the two sequences (3.17 ± 0.83 for 2D vs. 3.25 ± 0.75 for 3D, p = 0.655).
Conclusions This animal study suggests that the new free-breathing 3D PSIR Turbo FLASH sequence is feasible for accurate assessment of left ventricular myocardial scar volume and transmurality, without the need of breath holds during the acquisition required for the 2D PSIR Turbo FLASH sequence.