Irreversible myocardial injury: Assessment with cardiovascular delayed-enhancement MR imaging and comparison of 1.5 and 3.0 T - Initial experience

Purpose: To prospectively compare visualization and quantification of irreversible myocardial injury in patients with chronic myocardial infarction at 1.5- and 3.0-T magnetic resonance ( MR) imaging. Materials and Methods: The institutional research ethics committee approved the study. Participants gave written informed consent. Sixteen male patients ( mean age, 66 years +/- 13 [ standard deviation]) with myocardial infarction were imaged with the same sequence by the same operator at 1.5 and 3.0 T. After cine imaging, a bolus of gadodiamide was administered. Short-axis images of entire left ventricle ( LV) were acquired with a breath-hold T1-weighted segmented inversion-recovery turbo fast low-angle shot ( FLASH) sequence. Agreement for myocardial hyperenhancement ( HE) mass between field strengths was assessed with Bland-Altman method; agreement for detection and transmural extent of HE was assessed with kappa statistics. Intra- and interobserver reproducibility of mass and transmural extent of HE were assessed at 1.5 and 3.0 T. Results: Bland-Altman analysis revealed no systematic bias ( mean difference, 0.2 g; 95% confidence interval: -0.7 g, 1.2 g) and acceptable limits of agreement ( -3.3 to 3.8 g) between field strengths for HE mass. HE mass measurements were strongly correlated ( R-2 = 0.99); there was no significant difference in measurements at 1.5 and 3.0 T ( 28.1 g +/- 15.7 [ 22.6% +/- 10.9 of LV mass] vs 27.8 g +/- 15.7 [ 22.3% +/- 10.7 of LV mass], respectively; P = .599). For all segments, there was a high degree of agreement for HE detection ( kappa = 0.90) and transmural grade ( kappa = 0.79) between field strengths. Intra- and interobserver variability were low between both field strengths. Initial inversion time selected to null the signal of normal myocardium at 3.0 T was 57 msec +/- 20 longer than at 1.5 T ( P < .01). Conclusion: By using the same turbo FLASH MR pulse sequence, there was strong agreement in mass and transmural extent of myocardial HE between 1.5 and 3.0 T.