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Title: Detection of radiation induced lung injury in rats using dynamic hyperpolarized {sup 129}Xe magnetic resonance spectroscopy

Purpose: Radiation induced lung injury (RILI) is a common side effect for patients undergoing thoracic radiation therapy (RT). RILI can lead to temporary or permanent loss of lung function and in extreme cases, death. Combining functional lung imaging information with conventional radiation treatment plans may lead to more desirable treatment plans that reduce lung toxicity and improve the quality of life for lung cancer survivors. Magnetic Resonance Imaging of the lung following inhalation of hyperpolarized{sup 129}Xe may provide a useful nonionizing approach for probing changes in lung function and structure associated with RILI before, during, or after RT (early and late time-points). Methods: In this study, dynamic{sup 129}Xe MR spectroscopy was used to measure whole-lung gas transfer time constants for lung tissue and red blood cells (RBC), respectively (T{sub Tr-tissue} and T{sub Tr-RBC}) in groups of rats at two weeks and six weeks following 14 Gy whole-lung exposure to radiation from a {sup 60}Co source. A separate group of six healthy age-matched rats served as a control group. Results: T{sub Tr-tissue} values at two weeks post-irradiation (51.6 ± 6.8 ms) were found to be significantly elevated (p < 0.05) with respect to the healthy control group (37.2 ± 4.8 ms).more » T{sub Tr-RBC} did not show any significant changes between groups. T{sub Tr-tissue} was strongly correlated with T{sub Tr-RBC} in the control group (r = 0.9601 p < 0.05) and uncorrelated in the irradiated groups. Measurements of arterial partial pressure of oxygen obtained by arterial blood sampling were found to be significantly decreased (p < 0.05) in the two-week group (54.2 ± 12.3 mm Hg) compared to those from a representative control group (85.0 ± 10.0 mm Hg). Histology of a separate group of similarly irradiated animals confirmed the presence of inflammation due to radiation exposure with alveolar wall thicknesses that were significantly different (p < 0.05). At six weeks post-irradiation, T{sub Tr-tissue} returned to values (35.6 ± 9.6 ms) that were not significantly different from baseline. Conclusions: Whole-lung tissue transfer time constants for{sup 129}Xe (T{sub Tr-tissue}) can be used to detect the early phase of RILI in a rat model involving 14 Gy thoracic {sup 60}Co exposure as early as two weeks post-irradiation. This knowledge combined with more sophisticated models of gas exchange and imaging techniques, may allow functional lung avoidance radiation therapy planning to be achievable, providing more beneficial treatment plans and improved quality of life for recovering lung cancer patients.« less
Authors:
 [1] ; ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [7]
  1. Department of Physics and Astronomy, Western University, London, Ontario, N6A 3K7, Canada and Imaging Research Laboratories, Robarts Research Institute, Western University, London, Ontario, N6A 5B7 (Canada)
  2. Imaging Research Laboratories, Robarts Research Institute, Western University, London, Ontario, N6A 5B7 (Canada)
  3. Department of Medical Biophysics, Western University, London, Ontario, N6A 5C1, Canada and Imaging Research Laboratories, Robarts Research Institute, Western University, London, Ontario, N6A 5B7 (Canada)
  4. Department of Physics and Astronomy, Western University, London, Ontario, N6A 3K7, Canada and London Regional Cancer Program, London, Ontario, N6C 2R6 (Canada)
  5. Department of Radiation Oncology, University of Toronto, Toronto, Ontario, M5S 3E2, Canada and Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, M5T 2M9 (Canada)
  6. Department of Medical Biophysics, Western University, London, Ontario, N6A 5C1 (Canada)
  7. (Canada)
Publication Date:
OSTI Identifier:
22412469
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 41; Journal Issue: 7; Other Information: (c) 2014 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ANIMAL TISSUES; BLOOD CELLS; COBALT 60; LUNGS; NEOPLASMS; NMR IMAGING; RADIOTHERAPY; RATS; XENON 129