Magnetic resonance imaging-guided radiation therapy using animal models of glioblastoma

Abstract

Glioblastoma is the most aggressive and most common malignant primary brain tumour in adults and has a high mortality and morbidity. Because local tumour control in glioblastoma patients is still elusive in the majority of patients, there is an urgent need for alternative treatment strategies. However, to implement changes to the existing clinical standard of care, research must be conducted to develop alternative treatment strategies. A novel approach in radiotherapy is the introduction of pre-clinical precision image-guided radiation research platforms. The aim of this review is to give a brief overview of the efforts that have been made in the field of radiation research using animal models of glioblastoma. Because MRI has become the reference imaging technique for treatment planning and assessment of therapeutic responses in glioblastoma patients, we will focus in this review on small animal radiotherapy combined with MRI.

Figure 1.

Simplified overview of animal models of glioblastoma

Figure 2.

MR/CT-based workflow for small animal radiation treatment.

Figure 3.

Using fuzzy c-means clustering a segmented CT image was generated using four different MR sequences: T₁W, and T₂W, UTE and ZTE. This segmented CT images can be used for dose calculations. T₁W, T₁ weighted; T₂W, T₂ weighted; UTE, ultra-short echo time; ZTE, zero echo time.

Figure 4.

Glioblastoma and radiation necrosis are both heterogeneously hyperintense on T₂ weighted MR images (top). Moreover, a similar contrast enhancement pattern is observed on T₁ weighted contrast-enhanced MR images (bottom).