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Determining Whole Lung Perfusion Using Hyperpolarized Xe-129 MRI

Determining Whole Lung Perfusion Using Hyperpolarized Xe-129 MRI. Ian Gerard Department of Medical Biophysics University Of Western Ontario Six Week Project. z. m. x. y. MR Imaging Basics. B 1. Sample. RF Coil. Gradient Coil Set. Magnet. z. y. x. Hyperpolarized Media.

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Determining Whole Lung Perfusion Using Hyperpolarized Xe-129 MRI

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  1. Determining Whole Lung Perfusion Using Hyperpolarized Xe-129 MRI Ian Gerard Department of Medical Biophysics University Of Western Ontario Six Week Project

  2. z m x y MR Imaging Basics B1 Sample RF Coil Gradient Coil Set Magnet z y x

  3. Hyperpolarized Media Isotope Spin* 107rad s/TP(ppm) 1H 1/2 26.75 5.11 3He 1/2 20.37 3.89 13C 1/2 6.73 1.28 129Xe -1/2 7.40 1.41 (For T = 300K and B0 = 3 T ) In General After Hyper-polarization Method

  4. Gas Exchange Model ¶ ¶ 2 ( , ) ( , ) D C r t C r t - = 0 ¶ ¶ 2 r t æ ö - t t = - + t T ( ) 1 S S e S ç ÷ TR 0 1 è ø Xe Xe Xe Xe Xe Xe = αλ (1 – H)F Fig 1: Alveolar-Capillary model of Mansson [2]. Va is the alveolar volume measured at standard temperature and pressure. ra is the radius of the alveolus. Lt and Lc are the compartment lengths for tissue and capillary. C(r,t) is the xenon concentration in each respective compartment as a function of distance and time. F is the rate of pulmonary flow. Fin=Fout. S pl 1

  5. Methods Medical Air & O2 Ventilator Valve Assembly 3He Or 129Xe Acid Port 3T MRI Scanner Ventilator Heater Rb Reservoir Polarization Cell Gas Cylinder89% 4He 10% N2 1% Xe 794.8nm Circular Polarizer Magnet Polarized 129Xe Out Polarized 129Xe and 3He

  6. Pilot Results: Xenon

  7. Pulse Sequence Chemically Selective Saturation Recovery (CSSR) ~193ppm RF Pulse 90o 90o f Dissolved Phase Maximized Gas Phase Minimized t Loop N. Abdeen et al (2006)

  8. Spectroscopy After Applying Pulse Sequence Mansson Model: Valid for all time.

  9. Tissue Spectroscopy and Model Fit Mansson Model:

  10. Results: Representative Figure Linear fit applied to long time values Slope and intercept values are S1 and S0 respectively and used to calculate lung perfusion

  11. Calculated Lung Perfusion Typical Perfusion value from control rat 1.2 ± 0.2 Mansson et al.

  12. Perfusion and PIP • Appears to be some relationship between PIP value and Perfusion

  13. Discussion • Values agree with control perfusion from Mansson et al. • Something interesting may be happening at low pressure. • There may be a relationship between Perfusion and PIP • Hematocrit and typical perfusion values used were for Wistar rats while Sprague-Dawley rats were actually used but assumed equal for the project

  14. Conclusions and Future Work • Successfully able to estimate whole lung perfusion using Mansson model and other minor assumptions • Investigate the effects of low PIP on perfusion • Next Step: Create a perfusion map determining lung perfusion on a pixel by pixel basis

  15. Giles Santyr Matthew Fox Alexei Ouriadov Ryan Kraayvanger William Dominguez Wilfred Lam Peggy Xu Adam Farag Marcus Couch Heather Cadieux Eugene Wong Jake Van Dyk Acknowledgements Lynda McCaig Ruud Veldhuizen Jim Lewis Funding:

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