Glioma Morphology and Tumor-Induced Vascular Alterations Revealed in Seven Rodent Glioma Models by In Vivo Magnetic Resonance Imaging and Angiography

Purpose: To evaluate the added value of non-contrast-enhanced MR angiography (MRA) to conventional MR imaging for a detailed characterization of different rodent glioma models. Materials and Methods: Intracerebral tumor cell implantation and chemical induction methods were implemented to obtain rat C6. 9L/LacZ, F98. RG2, and ethyl-nitrosourea (ENU) -induced glioma models, a human U87 MG tumor model as well as a mouse GL261 glioma model. MR assessments were regularly conducted on a 7 Tesla Bruker BioSpin system. The tumor border sharpness and growth characteristics of each glioma model were assessed from T-2-weighted images. Neovascularization and vascular alterations inherent to each model were characterized by assessing absolute blood volumes, vessel density, length. and diameter using Mathematica and Amira software. Results: The 9L/LacZ and ENU gliomas both presented flaws that hinder their use as reliable brain tumor models. CO gliomas were slightly invasive and induced moderate vascular alterations, whereas GL261 tumors dramatically altered the brain vessels in the glioma region. F98, RG2. and U87 are infiltrative models that produced dramatic vascular alterations. Conclusion: MRI and MRA provided crucial in vivo information to identify a distinctive "fingerprint" for each of our seven rodent glioma models.