Gd-DTPA as an MRI Contrast Agent

Lindsay DodsApril 6, 2010Supervisors: Robert Ta, Masters Student Robert Bartha, Ph.D.

Introduction

MRI – Magnetic Resonance Imaging Can be used to detect anatomical

structures and function. Contrast Agents

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

Using Regression Analysis, P<0.05, therefore result is significant.

T1 - Contast over Time

0

0.5

1

1.5

2

2.5

0 1 2 3 4 5 6 7

Time (Days)

Co

ntr

ast

Results

T2 Contrast Over Time

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 1 2 3 4 5 6 7

Time (Days)

Co

ntr

ast

Using Regression Analysis, P<0.05, therefore result is significant.

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.