Neuroimaging Assessment of Subarachnoid Hemorrhage - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 426

similar scanner/coil with comparable capabilities (Fig. 4 ). Imaging
resolution on this instrument is on the order of ~100 μ m in all

directions.
When performing MRI on rats, one can use a Bruker 4.7 T
30 cm horizontal bore instrument equipped with 250 mT/m
microgradients (slew rate 1,000 mT/s) and a 116 mm (internal
diameter) quadrature receiver coil or similar scanner/coil with
comparable capabilities (Fig. 4 ). Imaging resolution on this instru-
ment is on the order of ~200

μ m in all directions.

2.3. Analysis Materials

Upon completion of the MRI acquisition, analysis of the SAH
lesion can be processed using a variety of methods. At the present
time, the only commercially available program to process the SWI
datasets is a clinical SWI package from Siemens. This automatically
processes the SWI data during image reconstruction but gives no
user selectable options. SWI analysis routines can be programmed
in a variety of programming languages. We currently use a custom-
ized program, SPIN, that was developed by our collaborators ( 36 )
and can be made available to other researchers. Other groups have
developed similar programs that are also made available to the
researcher community ( 32 ). See Note 3.

3. Methods

Multicontrast MRI can be employed to visualize SAH in a nonin-
vasive manner (Figs. 1 - 3 ). Under isofl uorane anesthesia the animal
can be placed either supine or prone positions on a bed that can be
inserted into the MRI. This bed and how the animal is attached
will vary between users. In our own laboratory, we place the ani-
mals in a prone position and the motion of the animal is minimized
by use of a Delron plastic stereotactic holder (see Fig. 4c , d).
Anesthesia gases fl ow through a nose cone similar to commercially
available surgical stereotactic holders. To best visualize SAH, one
can perform several imaging sequences, including FLAIR and SWI
sequences in both coronal and sagittal planes of view using the
following parameters; see Note 4:
Typical imaging parameters at 4.7 T are listed below:
FLAIR . TR/TE = 8,000 ms/40 ms, TI = 3,000 ms, NEX = 2,
FOV = 2.8 cm, matrix = 256 2 , slices = 25, slice thickness = 1 mm,
and slice interval = 1 mm.
SWI . 2D fl ow compensated GRE sequence, TR/TE = 1,250 ms/
20 ms, NEX = 6, FOV = 3 cm, matrix = 256 2 , slices = 32, resolution
117 × 117 × 800

3.1. Magnetic
Resonance Imaging

m 3 , slice interval = 0.8 mm, and TA = 32 min.
These imaging sequence parameters can be altered as needed
using the user interface on the MRI. A 3D sequence can also be

μ