Gd-DTPA as an MRI
Contrast Agent
Lindsay Dods
April 6, 2010
Supervisors: Robert Ta, Masters Student
Robert Bartha, Ph.D.
Introduction

MRI – Magnetic Resonance Imaging


Contrast Agents


Can be used to detect anatomical
structures and function.
Can enhance the contrast of an MRI
image, allowing for increased
differentiation.
Novel Contrast Agents must be
tested
Objectives


Show the effectiveness of Gd-DTPA
(Magnevist) as a contrast agent in
high field MRI.
As this agent is known to be
effective, the true objective is to
assess the testing protocol before
using novel contrast agents.
Approach

Compare contrast in mice brains



before and after incubation in contrast
agent
different incubation times.
Contrast is ratio of mean signal
intensity of the brain compared to
control
Hypothesis



The mean signal intensity of the
brain will increase with the addition
of contrast agent
This signal intensity will continue to
increase over time, until a
saturation point is reached
Intensity of the control is to remain
constant.
Methods

Prepare Samples


Split fixed brain
into two
hemispheres
Incubate one side
of the brain in
diluted Gd-DTPA,
use other side as
control
Methods

Scan



Perform T1 and T2
waited scans with a
9.4 T MRI.
Measure mean grey
level of each
hemisphere from
select slices in
ImageJ
Calculate Contrast
Results

Day 1, T2

Day 6, T2
Results
T1 - Contast over Tim e
2.5
Contrast
2
1.5
1
0.5
0
0
1
2
3
4
5
6
Tim e (Days)

Using Regression Analysis, P<0.05, therefore
result is significant.
7
Results
T2 Contrast Over Tim e
1.6
1.4
Contrast
1.2
1
0.8
0.6
0.4
0.2
0
0
1
2
3
4
5
6
Tim e (Days)

Using Regression Analysis, P<0.05, therefore
result is significant.
7
Discussion



Results aren’t as expected
Paramagnetic contrast agents alter
signal intensity by shortening
relaxation time of protons
Increase in signal intensity is
beneficial
Future Work


Contrast agent in disease diagnosis
Use this protocol on novel contrast
agents
Conclusion


Results were not conclusive to show
that signal intensity increased over
time with the addition of a contrast
agent.
More samples are needed to
determine if this protocol is an
effective way to test contrast
agents.