Assessment of Myocardial Viability by Late Enhancement MR Imaging at 3.0 Tesla versus 1.5 Tesla

Purpose: In patients suffering from coronary artery disease, determination of myocardial viability by late enhancement (LE) MR imaging (MRI) is of increasing relevance. Despite good results at 1.5T, imaging at 3.0T should provide a significant improvement in contrast (CNR) and signal (SNR) to noise ratio. Aim of this study was to investigate SNR, CNR and image quality of LE-MRI at 3.0T in comparison to 1.5T.

Methods: In 15 patients with myocardial infarction cardiac MRI was performed at 1.5T (Magnetom Sonata, Siemens, Germany) and in 15 patients at 3.0T (Magnetom Trio, Siemens, Germany). Myocardial function was assessed by 2D-Cine trueFISP sequences acquired in long and short axes views. After administration of 0.15 mmol Gd-DTPA/kg late enhancement images were obtained using a segmented inversion recovery prepared Turbo FLASH sequence (Sonata: TR 600, TE 4.38, flip 25°, matrix 208×256, Trio: TR 750, TE 4.3, flip 30° matrix 166×256). For image analysis measurements of SNR and CNR were performed in infarcted and normal myocardial regions. Furthermore, two independent observers rated image quality on a 4-point scale (0=poor, 3=excellent).

Results: High quality images were obtained in all patients at 1.5 and 3.0T. In infarcted myocardium the average SNR was 47.3+13.5 at 3.0T versus 25.9+13.0 at 1.5T (p<0.001). In normal myocardium SNR was 6.6+2,4 at 3.0T and 7.48+2.6 at 1.5T (p=0.67 (non significant)). CNR was 40.6+13.1 at 3.0T and 18.5+12.1 at 1.5T (p<0.001). Rating of image quality was 2.5+0.4 at 1.5T and 2.9+0.1 (p<0.05) at 3.0T.

Conclusion: Evaluation of myocardial viability at 3.0T is feasible. Our results indicate that SNR as well as CNR are substantially increased at 3.0T using identical contrast doses. The potential clinical benefit of late enhancement MRI at 3.0T has to be investigated by further trials.