Functional Imaging – Application of microvascular imaging to assess tumor response to radiation therapy

Molecular Imaging of Therapeutic Response

Sunny Kasoji – Application of microvascular imaging to assess tumor response to radiation therapy

Radiation therapy is one of the most basic and common forms of cancer treatment. In fact, its therapeutic effects were discovered soon after the discovery of cancer itself. Unfortunately, the effects of radiation on the various microenvironments of cancer cells are still not well understood. Currently, the standard of care for assessing tumor response to therapy is “Response Evaluation Criteria in Solid Tumors” (RECIST), which evaluates tumor response based on changes in tumor volume. However, changes in tumor volume do not occur for weeks to months after treatment. For patients whose tumors are not successfully treated, this is wasted time, since a prompt switch to a different treatment strategy is critical. Our team (The Dayton Lab in collaboration with Dr. Sha Chang, medical physicist in Radiation Oncology) is interested in the effect of radiation on the tumor microvasculature. The microvasculature plays an important role in providing oxygen and nutrients to the rapidly growing tumor. Prior research has shown that tumor microvasculature responds very quickly (on the order of 1-2 days) to radiation. Our hypothesis is that by quantifying microvascular changes post-radiation therapy, we will be able to predict treatment response earlier than the current standard of care.

Figure 1. A) A standard anatomical b-mode image of a rat FSA tumor and B) an acoustic angiography image of the same region. Arrows indicate the location of the tumor.

We are currently exploring a more advanced type of radiation therapy, specifically spatially-fractionated, or microbeam radiation therapy, which has shown evidence of equally effective tumor control with decreased radiation dose and toxicity.