preserving hyperpolarization of 129 xe for transport zach zytner project supervisor: giles santyr...
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Preserving Hyperpolarization of 129Xe for Transport
Zach ZytnerProject Supervisor: Giles Santyr
Medical Biophysics 3970March 23, 2011
Introduction
• MR imaging with hyperpolarized noble gases – Greater resolution in lung imaging without
harmful radiation– Effectiveness depends on nuclei high-spin
polarization achieved outside system
• Preserving the 129Xe polarization permits transporting the HNG to other research sites
Transportation Box
Solenoid coil 12V NiMH Battery
Glassvial
Current control
Current display (mA)
Powerswitch
Recharging terminal• Solenoid coil (ID 15.3cm) • Power supply (battery - 1650mA)
Method I: Project LayoutXe sample
Solenoid coil
• Sustainability of battery• Collection of polarized Xe• Signal data at time
intervals through polarimetry
• Determination of box’s T1
Method II: Mapping the Field with Current
• Maximum current = 1650 mA
• Maximum field = 36.5 G (3.65 mT)
Method III: Characterizing Field vs. Time
• 18 hour charge shows rapid decay of field
• Best charging time shows box can maintain magnetic field
Polarimetry StationHelmholtz Coil
RF coilStage for gas sample
• Pulse and response frequencies within 50Hz for accurate measurement of signal
Longitudinal Spin Relaxation• Optical pumping of Rb followed by spin
exchange with Xe nucleus• Longitudinal relaxation time (T1) is the time
taken to return to equilibrium within the lattice after an RF pulse excitation
Results I: Signal for 90mL Xe bag at t = 2 mins
Results II: Signal for 90mL Xe bag at t = 122 mins
Results III: Response Amplitude from Excel Trend Lines vs. Time
• Extrapolated signal @ t = 0 is 27.5mV
• Signal = 5.37 mV at 122 mins
Results IV: Response Amplitude from Polarimetry Software Trend Lines vs. Time
• Extrapolated signal @ t = 0 is 43.1 mV
• Signal = 2 mV at 122 mins
Results V: T1 Determination
• Signal from Excel trend lines
T1 = 75 mins = 1.25 hrs
• Signal from polarimetry software trend lines
T1 = 40 mins = 0.67 hrs
Discussion• With the current battery, transportation box
must be charged more than 24 hours to maintain a sustainable magnetic field
• Signals obtained from the station is contaminated with noise
• With the current signals at ~ t = 0, T1 found to be 40-75 minutes
Conclusions
• The transportation box could likely preserve hyperpolarization in 129Xe if travelling short distances
• Recommendation: use battery with long life with short charging time
Acknowledgements
Giles SantyrAdam FaragMathieu BoudreauAlexei OuriadovMatthew FoxMarcus CouchJulie TanguayIan GerardElaine Hegarty
Funding:
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