Black blood gradient echo cine magnetic resonance imaging of the mouse heart

A black blood gradient echo sequence for multiphase cardiac MRI of the mouse heart was implemented on a 4.7-T scanner and compared to a conventional bright blood sequence. Black blood was achieved using the double inversion recovery technique. Ten mice were imaged using both the bright and the black blood sequences, and 2 of the mice were additionally imaged using bright and black blood sequences modified to perform myocardial tagging. Manual planimetry of the images was performed by two independent observers to detect the endocardial and epicardial borders and subsequently to compute chamber volumes and myocardial mass. Weight of the excised left ventricle was used as a gold standard for myocardial mass. Bland-Altman analysis demonstrated reduced interobserver variability for the measurement of cardiac volumes using the black blood sequence compared to the bright blood sequence (95% confidence interval was -0.89-0.73 μL for black blood versus -1.85-1.28 μL for bright blood). Also, Bland-Altman analysis showed that the black blood sequence provides improved accuracy for the measurement of myocardial mass compared to the bright blood sequence (average difference between MRI versus weight was 0.9 μg for black blood and -11.2 μg for bright blood, P <0.01). For myocardial tagging, qualitative assessment demonstrated improved endocardial border definition using the black blood sequence. Black blood cine MRI in mice provides reduced interobserver variability and improved accuracy for the measurement of myocardial volumes and mass compared to the conventional bright blood technique.