Fast and robust 3D T-1 mapping using spiral encoding and steady RF excitation at 7T: application to cardiac manganese enhanced MRI (MEMRI) in mice

摘要

Mapping longitudinal relaxation times in 3D is a promising quantitative and non-invasive imaging tool to assess cardiac remodeling. Few methods are proposed in the literature allowing us to perform 3D T-1 mapping. These methods often require long scan times and use a low number of 3D images to calculate T-1. In this project, a fast 3D T-1 mapping method using a stack-of-spirals sampling scheme and regular RF pulse excitation at 7T is presented. This sequence, combined with a newly developed fitting procedure, allowed us to quantify T-1 of the whole mouse heart with a high spatial resolution of 208 x 208 x 315 mu m(3) in 10-12min acquisition time. The sensitivity of this method for measuring T-1 variations was demonstrated on mouse hearts after several injections of manganese chloride (doses from 25 to 150 mu molkg(-1)). T-1 values were measured in vivo in both pre- and post-contrast experiments. This protocol was also validated on ischemic mice to demonstrate its efficiency to visualize tissue damage induced by a myocardial infarction. This study showed that combining spiral gradient shape and steady RF excitation enabled fast and robust 3D T-1 mapping of the entire heart with a high spatial resolution. Copyright (c) 2015 John Wiley & Sons, Ltd.