Imaging Modalities to Assess Oxygen Status in Glioblastoma

Abstract

Hypoxia, the result of an inadequacy between a disorganized and functionally impaired vasculature and the metabolic demand of tumor cells, is a feature of glioblastoma. Hypoxia promotes the aggressiveness of these tumors and, equally, negatively correlates with a decrease in outcome. Tools to characterize oxygen status are essential for the therapeutic management of patients with glioblastoma (i) to refine prognosis, (ii) to adapt the treatment regimen, and (iii) to assess the therapeutic efficacy. While methods that are focal and invasive in nature are of limited use, non-invasive imaging technologies have been developed. Each of these technologies is characterized by its singular advantages and limitations in terms of oxygenation status in glioblastoma. The aim of this short review is, first, to focus on the interest to characterize hypoxia for a better therapeutic management of patients and, second, to discuss recent and pertinent approaches for the assessment of oxygenation/hypoxia and their direct implication for patient care.

Keywords: MRI; PET; glioblastoma; hypoxia; multimodal imaging.

Figure 1

Schematic representation of the negative role of hypoxia in tumor growth and therapeutic response in glioblastoma. The growth of a GBM is a feed-forward (vicious) cycle exacerbated by hypoxia as depicted in red. Hypoxia renders the tumor less susceptible to standard chemo-(CT) and radio-therapy (X-ray) as shown in blue. Future treatment strategies are indicated in purple.