Early Assessment of Tumor Response to Radiation Therapy Using Ultrasound Molecular Imaging In Vivo

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  • February 26, 2019
Creator
  • Patel, Ruby
    • Affiliation: School of Medicine, UNC/NCSU Joint Department of Biomedical Engineering
Abstract
  • Introduction: Earlier evaluation of treatment response to radiation therapy (RT) could lead to better prognoses for cancer patients. Tumors exhibit vascular remodeling while they are growing, which indicates an increase in the expression of angiogeneic proteins such as vascular endothelial growth factor (VEGF). We hypothesize that molecular imaging using contrast enhanced ultrasound (CEUS) is able to detect longitudinal changes in tumor microvasculature after radiation therapy before changes in tumor volume or vascular density actually manifest.Methods: Fibrosarcoma tumors were implanted in Female Fischer 344 rats (n=10). When the tumors reached approximately 1 cm in diameter, they were either treated with 20 Gy broad beam radiation (n=8) or left untreated (control, n=2). All animals were imaged prior to, and serially twice a week after, treatment. Imaging consisted of VEGFR-2 molecular imaging with contrast enhanced ultrasound. The molecular targeting for each timepoint was quantified. Results: Molecular targeting assessment showed no significant increase in VEGFR-2 expression before tumor regrowth. Moreover, molecular targeting, peak perfusion, and area under the time-intensity curve (TIC) decreased throughout the duration of the study. Discussion/Conclusion: The ability of molecular imaging to detect changes in tumor microvasculature was not verified in this study. However, it is not possible to conclude a true negative finding among the results due to several confounding variables and study limitations, such as unpredictable tumor response, microbubble inconsistences, and varying perfusion rates. The results from this study indicate that it needs to be modified and repeated. Therefore, although VEGFR-2 has the potential to be a biomarker for tumor response to radiation therapy, it is not possible to definitively determine its utility as a means of tumor microvasculature assessment from this study alone.
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  • In Copyright
Advisor
  • Dayton, Paul
Degree
  • Bachelor of Science
Academic concentration
  • Biomedical Engineering
Honors level
  • Honors
Degree granting institution
  • University of North Carolina at Chapel Hill
Graduation year
  • 2018
Language
  • English

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