Electronic Thesis and Dissertation Repository


Master of Science


Medical Biophysics


Giles Edmund Santyr


Background: Early diagnosis of radiation-induced lung injury (RILI) following radiation therapy is critical for prevention of permanent lung damage. Pulmonary imaging using magnetic resonance imaging (MRI) of the apparent diffusion coefficient (ADC) of hyperpolarized xenon (129Xe) gas shows promise for early measurement of RILI.

Methods: An ultra-short echo time imaging sequence based on a pseudo-Cartesian k-space trajectory, known as Sectoral, is implemented at low magnetic field (0.07 T) for efficient use of the non-renewable magnetization of hyperpolarized 129Xe gas. A pilot study was performed to demonstrate the feasibility of ADC mapping using the Sectoral sequence on healthy and 2-weeks post irradiated rats.

Results: A significant (p < 0.05) correlation between mean ADC values from Sectoral ADC maps and the mean linear intercept (Lm), as a measure of interalveolar wall distance, from histological sections of the lungs was observed (p = 0.0061) and a significant (p < 0.05) separation between healthy and irradiated lungs was observed with full width at half maximum ADC (p = 0.0317).

Conclusion: Sectoral MRI with 129Xe is feasible in rats. Decreases in ADC were measured following lung irradiations which correlate with Lm.