Events Calendar

New Perfusion, pH-, and Hypoxia-weighted MRI Approaches for Characterizing the Tumor Microenvironment in Human Glioblastoma

Speaker: Benjamin Ellingson, Ph.D., University of California, Los Angeles

Talk Title: New Perfusion, pH-, and Hypoxia-Weighted MRI Approaches for Characterizing the Tumor Microenvironment in Human Glioblastoma

Series: Medical Imaging Seminar Series

Abstract: Interstitial tissue acidosis and hypoxia resulting from abnormal perfusion and metabolism are a hallmark of cancer. This low extracellular pH and O2 has dramatic consequences, as it is directly linked to the degree of malignancy as demonstrated by elevated mutagenesis, increased populations of cancer stem cells, activation of various oncologic pathways, increased tumor invasion, immunosuppression, increased angiogenesis, and resistance to radiation and certain chemotherapies. Relatively limited in vitro, preclinical, and clinical evidence supports the hypothesis that acidosis and hypoxia play important roles in gliomagenesis; however, there remains a critical gap in furthering our understanding of the role of extracellular acidosis and hypoxia in human gliomas and its clinical relevance due to the lack of a robust non-invasive tool for measuring and localizing regions of low pH and oxygen concentration. Additionally, perfusion-weighted MRI techniques such as dynamic susceptibility contrast (DSC) MRI are routinely used for quantification of tumor perfusion; however, current approaches for clinical DSC-MRI have several limitations including need for adequate post-hoc leakage correction, limited biomarkers for quantifying vascular heterogeneity and hypervascular tumor volume, and limited information about vascular architecture. To overcome these limitations we have developed a new method for obtaining fast, high spatial resolution pH- and hypoxia-weighted molecular MR imaging of human gliomas using multi-echo amine chemical exchange saturation transfer echo planar imaging (CEST-EPI). The technique works by targeted saturating the longitudinal magnetization of amine protons on glutamine (3.0ppm), a major source of fuel for tumor cells, as they undergo pH-dependent chemical exchange with water protons. Using a multi-echo readout of the MR signal during CEST EPI allows for simultaneously obtaining measurements of transverse relaxation rates, which are dependent on oxygenation of the tissue. Lastly, we will describe new approaches for DSC perfusion MRI, including new acquisition strategies, leakage correction algorithms, and methods for quantifying vascular heterogeneity and architecture.


Host: Professor Krishna Nayak

Location: Hughes Aircraft Electrical Engineering Center (EEB) - 132

Audiences: Everyone Is Invited

Contact: Talyia Whtie