Accelerated cardiac magnetic resonance imaging in the mouse using an eight‐channel array at 9.4 Tesla

Abstract

MRI has become an important tool to noninvasively assess global and regional cardiac function, infarct size, or myocardial blood flow in surgically or genetically modified mouse models of human heart disease. Constraints on scan time due to sensitivity to general anesthesia in hemodynamically compromised mice frequently limit the number of parameters available in one imaging session. Parallel imaging techniques to reduce acquisition times require coil arrays, which are technically challenging to design at ultrahigh magnetic field strengths. This work validates the use of an eight-channel volume phased-array coil for cardiac MRI in mice at 9.4 T. Two- and three-dimensional sequences were combined with parallel imaging techniques and used to quantify global cardiac function, T1-relaxation times and infarct sizes. Furthermore, the rapid acquisition of functional cine-data allowed for the first time in mice measurement of left-ventricular peak filling and ejection rates under intravenous infusion of dobutamine. The results demonstrate that a threefold accelerated data acquisition is generally feasible without compromising the accuracy of the results. This strategy may eventually pave the way for routine, multiparametric phenotyping of mouse hearts in vivo within one imaging session of tolerable duration. Magn Reson Med, 2010. © 2010 Wiley-Liss, Inc.

Development of Real-Time Magnetic Resonance Imaging of Mouse Hearts at 9.4 Tesla— Simulations and First Application

“…Furthermore, time-volume analysis of the entire left ventricle showed that both diastole and systole have periods of 15–20ms, during which very little changes in left-ventricular volumes are observed (Fig. 6 of reference [12]). This is in line with early reports claiming that a temporal resolution of ~10 ms suffices to least determine end-diastole and end-systole with physiologically acceptable accuracy [1].…”

Functional and Morphological Cardiac Magnetic Resonance Imaging of Mice Using a Cryogenic Quadrature Radiofrequency Coil

“…RF coils tailored for CMR are dedicated birdcage volume coils or surface coil arrays with the geometry adjusted to the size of a mice (25–35 mm inner diameter or 15–26 mm side length respectively) [2], [4], [5], [6], [7], [8], [10]. An emerging RF coil technology for MRI of small rodents is the cryo-cooling of RF coils, which reduces the electronic noise.…”

High field magnetic resonance imaging of rodents in cardiovascular research

“…T1-mapping is commonly acquired with a sequence based on the look-locker method although some authors described SNAPSHOT-FLASH Inversion Recovery (SNAP-IR) [24,124] or variable flip angle [39] strategies for the acquisition. In mouse, the acquisition is mainly made in combination with a contrast agent, gadolinium [24,39,138] or manganese [8,77,87,88,168,169].…”

“…Each element is associated with an independent radiofrequency pathway whose signals can be processed and combined together. A combination of such overlapping multiple receiver coil elements can be utilized to improve the signal-to-noise ratio and allows to speed up acquisitions as the number of spatial encoding steps can be decreased and conventional Fourier encoding reduced [40,124].…”