Realtime Cine MRI in Mice with a Single-Shot EPI Sequence and The Karhunen–Loeve Transform

Background and Aims: Mouse models of cardiac disease play a major role in cardiovascular research but are frequently imaged with echocardiography rather than with MRI. While several groups have shown that MRI can image the mouse heart with an unparalleled level of breadth and detail, many in the cardiac research community remain concerned by the complexity and time-consuming nature of cardiac MRI in mice. Here we present a technique to perform realtime cine MRI in mice with an ungated single-shot echoplanar (EPI) gradient echo sequence. We further show that the quality of the realtime cine images can be significantly improved through the application of a Karhunen–Loeve transform (KLT) filter. The KLT filter is an eigenimage filter that exploits the high degree of temporal correlation in realtime cardiac MR images, and has been shown to boost the SNR of realtime MRI in humans.