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 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.

Results  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.