Detection of Myocardial Edema with Low-b-value Diffusion-weighted Echo-planar Imaging Sequence in Patients with Acute Myocarditis

Abstract

To evaluate the performance of a low-b-value diffusion-weighted (DW) echo-planar (EP) imaging sequence for detection of regional and diffuse myocardial edema in patients with acute myocarditis. This study was approved by the institutional review board, and informed consent was obtained from all subjects. Thirteen patients with acute myocarditis and a control group of seven healthy adults underwent low-b-value (50 sec/mm(2)) DW cardiac magnetic resonance imaging. DW EP images were acquired in the four-chamber long-axis section and analyzed qualitatively and quantitatively. Short inversion time inversion-recovery (STIR) T2-weighted and late gadolinium chelate enhancement images were acquired in the same plane and analyzed. Late gadolinium chelate enhancement was used as the reference standard. Statistical analyses were performed with a receiver operating characteristic analysis and a nonparametric Wilcoxon test. Qualitative analysis showed myocardial high-signal-intensity areas in 100% (13 of 13) of patients on DW EP, 38% (five of 13) on STIR T2-weighted, and 100% (13 of 13) on late gadolinium chelate enhancement images. In eight patients (61%), high-signal-intensity areas were exhibited on DW EP images that were not detected on STIR T2-weighted images, but were colocalized with lesions detected on late gadolinium chelate enhancement images. Similar results were obtained by using an automatic analysis with dedicated cardiac software. The global myocardial signal intensity ratio was significantly higher (P = .03) in patients than in controls for DW EP (2.2 ± 0.4 [standard deviation] vs 1.1 ± 0.4, respectively), and exhibited no significant difference (P = .14) for STIR T2-weighted (1.7 ± 0.6 vs 1.4 ± 0.1, respectively) images. Sensitivity and diagnostic accuracy were higher for DW EP images than for STIR T2-weighted images (92% vs 54%, and 95% vs 70%, respectively), and specificity was the same (100% vs 100%). A low-b-value DW EP imaging sequence is a feasible alternative to the standard STIR T2-weighted sequence for detection of regional and global myocardium edema in patients with acute myocarditis. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13121811/-/DC1.