The Preclinical MRI Core Faciltiy runs MR spectroscopy or imaging
experiments on an hourly fee basis. We will be happy to discuss how MR
imaging can be used to further your research goals.
Standard applications of the lab include anatomic, T1, T2, diffusion, and
perfusion studies. In addition, global and localized spectroscopy
experiments are available for either proton or multinuclear applications.
Cultured tissue, excised organ, and in vivo model systems are utilized in
the following ongoing studies:
In Vivo Imaging
Anatomic in vivo imaging is routine in the head, thorax, and abdomen. Shown
are a mouse brain and kidney.
Angiographic images can also be obtained with flow compensated gradient
echo imaging. On the right is a 3 dimensional image of the vessels in a rat
Calculated Parameter Images
In some circumstances, calculated parameter images are desired. In the
example shown below, a T1 calculated image of cartilage demonstrates
substantial variation in T1 in the presence of Gd(DTPA).
Arterial Spin Labeling
Perfusion weighted imaging via arterial spin labeling is also available. In
the example shown below, the first image is an image obtained with
saturation of the spins (blood) in the neck region, leading to saturation
in the perfused area of the brain. The second image is the "control". A
calculated image is shown on the far right.
In Vivo Mouse Cardiac Imaging
Mouse cardiac imaging can be done on a vertical bore 8.5Tesla MRI system or
a horizontal bore 4.7Tesla system. Due to the ease of positioning and the
lower respiratory motion on the horizontal system, we currently are
pursuing most of the cardiac imaging on the 4.7T instrument.
Cardiac images can be obtained in both systole and diastole. The myocardium
in each section can be identified and planimetry used to determine the
volume of myocardium in each slice. The specific gravity of myocardium was
used to convert volume to mass. Ejection fractions can be computed from
diastolic and systolic images.
Images can be obtained throughout the cardiac cycle to produce cine loops
of cardiac motion.
Direct flow studies can be used to visualize flow within the heart. Fast
segmented gradient echo sequences with relatively high flip angles can be
used to highlight flow; regurgitant flow results in a signal void.
Small (approximately 2 mm) cartilage samples can be imaged with isotropic
50 micron resolution. In the images on the left, a 3D data set is obtained
of a cartilage sample; above left is the proton density image demonstrating
homogeneous tissue with small blood vessels. Above right is a T1 weighted
3D image demonstrating striking T1 variations across the sample. Bottom
left is one 2D section from the 3D data set, demonstrating good
correspondence with histology (bottom right).
Isolated organs can be imaged in 3D to demonstrate the internal anatomic
structures which are difficult to view with 2D histologic slides; on the
right is an isolated mouse heart; below left is a mouse knee; below right
is an isolated kidney.