Room: Exhibit Hall | Forum 8
Purpose: The goal of this study was to determine the sensitivity of in vivo MRI to radiation-induced lung pathology. We hypothesized that whole thorax irradiation will lead to radiation-induced lung injury that can be detected with MRI -- primarily pulmonary fibrosis. A further goal was to evaluate the effect of total dose on the onset of pathology and mortality.
Methods: C57BL/6 male mice received a dose between 15 to 30 Gy to the whole thorax from a 320 kVp X-RAD cabinet irradiator. Mice were irradiated in sets of 5 with lead shielding to irradiate only the thorax. Mice were imaged before irradiation and at intervals of 4 weeks post-irradiation with a Bruker 7T MRI. Scans of the lung were performed using an UTE scan to increase visibility of the lung parenchyma. Mice were sacrificed around the 20-30 week time point, depending on dose, for ex vivo histological assessment to validate the imaging findings.
Results: Areas of pathology were visualized as hyper-intense nodules within the lung. Areas of hyper-intensity were quantified using custom code in Matlab. Preliminary results show an increase in the number of aberrant tissue space in the lung over the 22 weeks of mice receiving 15 Gy. Further study and comparison needs to be done with the histology to conclude specific tissue aberrancies.
Conclusion: Results of the imaging analysis show a linear trend and increase to the estimated amount of aberrant tissue over time. This is expected if the analysis is showing fibrotic tissues, for the condition is supposed to worsen over time. Quantification of pulmonary fibrosis severity still needs to be performed at each time point, and current work is being performed to evaluate the dose-effect on our measurement. Overall, MRI appears to be a promising technique for tracking radiation-induced lung injury non-invasively.