Noninvasive In Vivo Small Animal MRI and MRS: Basic Experimental Procedures

Summary

This work describes basic procedures of noninvasive small animal MRI and MRS in vivo.

Abstract

Small animal Magnetic Resonance (MR) research has emerged as an important element of modern biomedical research due to its non-invasive nature and the richness of biological information it provides. MR does not require any ionizing radiation and can noninvasively provide higher resolution and better signal-to-noise ratio in comparison to other tomographic or spectroscopic modalities. In this protocol, we will focus on small animal MR imaging and MR spectroscopy (MRI/MRS) to noninvasively acquire relaxation weighted ¹H images of mouse and to obtain ³¹P spectra of mouse muscle. This work does not attempt to cover every aspect of small animal MRI/MRS but rather introduces basic procedures of mouse MRI/MRS experiments. The main goal of this work is to inform researchers of the basic procedures for in vivo MR experiments on small animals. The goal is to provide a better understanding of basic experimental procedures to allow researchers new to the MR field to better plan for non-MR components of their studies so that both MR and non-MR procedures are seamlessly integrated.

Protocol

Part 1: Magnet Safety

Both MRI and MRS use a strong magnetic field that requires extreme caution. For example, the 4.7 T instrument that we used for the present work has a magnetic field approximately 90,000 times the earth magnetic field. The high magnetic field is always on even when the MR scanner is not being used. Any metallic object that comes into contact with such a high magnetic field will be strongly and rapidly attracted by the magnet. It is extremely dangerous if an experimental subject or operator is located in the projectile path of a metallic object flying into the magnet. Therefore, personnel who conduct MR experiments should....

Discussion

The pre-acquisition steps of tune/match and shimming are critical to acquire high spatial resolution and a high signal-to-noise ratio (SNR). It is also important to monitor animal conditions with an animal monitoring system to maintain a stable physiological state for animals during signal acquisitions to comply with humane animal handling and to prevent any potential artifactual measurements. The procedures explained in the protocol can be modified to acquire additional information including diffusion, perfusion and flo.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Inova 200 MR scanner/4.7 T	Varian Inc., Agilent		Used for mouse MRI
Inova 300 NMR spectrometer/7 T	Varian Inc., Agilent		Used for MRS of mouse skeletal muscle