High speed cardiac cine MR imaging using keyhole method

While EGG-gated magnetic resonance imaging is widely used for cardiac imaging, it has several disadvantages such as long imaging time, respiratory artifacts, and motion artifacts induced by arrhythmia. An MR image can be acquired during about 0.3 seconds by using a fast gradient echo imaging method. When this method is continuously applied, only two to three images can be obtained during a single cardiac cycle. The goal of this study is to obtain cine MR images in a single cardiac cycle using a fast gradient echo imaging combined with "keyhole" method. The optimal condition of the keyhole method for cardiac cine imaging was considered with a computer simulation based on a simplified cardiac model. When the read-out direction was set parallel to the cardiac short axis, left ventricular motion was almost correctly reproduced by the keyhole method of which the acquisition time was reduced to one fourth.