A DTI study to probe tumor microstructure and its connection with hypoxia

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Oncology

Background:

• Solid tumors exhibit chaotic microenvironments, leading to hypoxia and radiation resistance.
• Understanding tissue organization and oxygen levels is crucial for predicting tumor behavior and guiding therapy.
• Diffusion Tensor Imaging (DTI) assesses tissue microstructure (FA), while Electron Paramagnetic Resonance Oxygen Imaging (EPROI) measures oxygen (pO2).

Purpose of the Study:

• To investigate the relationship between tissue microstructure organization (FA) and oxygen concentration (pO2) in tumors.
• To establish a potential link between DTI-derived FA and EPROI-measured pO2 for improved tumor characterization.

Main Methods:

• Fractional anisotropy (FA) was calculated using preclinical 9.4 T MRI in fibrosarcoma (FSa) models in mice.
• Partial pressure of oxygen (pO2) was measured using electron paramagnetic resonance oxygen imaging (EPROI).
• Correlation analysis was performed between FA and pO2 values in MCa4 tumors.

Main Results:

• FA was lower in tumor regions (0.34 ± 0.014) compared to surrounding normal tissue (0.36 ± 0.013).
• Preliminary in vivo results showed a positive correlation (R = 0.85, p = 0.017) between FA and pO2 in MCa4 tumors.

Conclusions:

• Tissue microstructure organization, indicated by FA, is altered in tumors.
• A positive correlation exists between FA and pO2 in tumors, suggesting FA as a potential biomarker for tumor hypoxia.
• This correlation could inform the use of DTI and pO2 measurements for targeted radiation therapy, potentially improving treatment efficacy and sparing healthy tissue.