Effects of low magnetic fields on T1values for hyperpolarized 13C

Pyruvic AcidBryan Addeman

April 6, 2010

Background Theory

Motivation

Measurements

Moving Forward

Agenda

Label specific metabolites with 13C

12C isotope is not magnetically active

Why use 13C instead of 1H?

What is hyperpolarization?

Natural abundance of 13C is ≈ 1.11%

Amount of signal is related to gyromagnetic ratio (γ) & abundance◦ γH = 42.58 (Mhz/T)

◦ γ13C = 10.71 (Mhz/T)

Hyperpolarization can give a factor of 10,000x more initial signal

Why does the sample need to be hyperpolarized?

Hyperpolarization Process

Inject sample mixed with free radical

Cool to 1.4 K in a High magnetic field

Bombard sample with microwaves

Mix with heated solution

Duration: 1.5 hours

Amount of Hyperpolarization decays with time (T1)

Robarts DNP Hyperpolarizer

The T1 Relaxation Process

Spin-Spin Relaxation Spin-Lattice Relaxation

T1T2

Pyruvic Acid

Effects of low magnetic fields on T1values for hyperpolarized 13C

Pyruvic Acid

Hyperpolarized sample transport:◦ Bo: High (DNP) -> Low -> High (MRI)

What happens to the sample in transit?

T1 relaxation is a characteristic of the molecule that can be measured

Motivation

Measuring T1

SpinmasterOxford Instruments MQC

Variable magnetic field◦ Bo = 0.0-0.9 T

Desktop NMR system◦ Bo = 0.55 T

Both devices can measure Signal amplitude at time intervals

Analysis

Bo=0.55, 13C enriched Pyruvic Acid

Fit Equation

Non-Linear Least Squares Fit

Spinmaster MQC (0.55 Static Field)

Field Strength (T)

T1 (s) Fit Error (s) T1 (s) Fit Error (s)

0.55 52.6 0.44 58.3 0.31

0.0235 68.7 0.25 87.0 0.82

0.0235 74.2 0.78 83.7 0.56

Results

Need to take more measurements to understand the effects low field strengths on T1 values

Conclusions

Acknowledgments Supervisors

Dr. Charles McKenzie Dr. Lanette Friesen-

Walder Dr. Tim Scholl Dr. Jake Onwuachi

Lab

Curtis Wiens Samantha Flood Steven Yange Elmer Soto Trevor Wade

Questions