Glioblastoma (GBM) and intraaxial metastases are most common brain malignancies with poorest prognosis. Average life expectancy of GBM patients undergoing postoperative radiochemotherapy is 14-16 months. Brain metastases define M1 stage of cancer process and a poor prognosis also. Both glioblastoma and solitary intraaxial metastases show similar diagnostic features while using standard MRI scanning protocol. Additional techniques such as contrast-enhanced and non-contrast MR-perfusion allow to detect increased cerebral blood flow velocity (CBF) and volume (CBV) in case of both pathologies, that unfortunately is not always enough to differentiate them.

Glioblastoma is a tumor with intensive neoangiogenesis which is characterised by releasing growth factors and mediators such as endothelial growth factor and aquaporine-4 that interact with perifocal tissues and cause increasing of peritumoral edema, that also includes tumor cells in its structure due to infiltrative growth. That allows us to suggest that perifocal edema of glioblastoma is an infiltrative tumor-like pathology itself that means more intensive blood supply comparing to intact white matter. On the contrary infiltrative growth is not a common feature of intraaxial metastases that are separated from brain parenchyma with a capsule - independently of their histology. Accordingly, metastatic edema is considered to be vasogenic and appears because of blood-brain barrier disruption and doesn’t include tumor cells in its structure.

Based on that we can suggest higher perfusion meanings in GBM perifocal edema comparing to intact white matter that could allow to differentiate glioblastoma and metastases more precisely. We also assume that increase of peritumoral edema in case of glioblastoma could predict tumor growth, increasing its metabolic activity or recurrence.

According to literature multiparametric MRI is a common used technique in brain tumors detection but mostly it is reported about tumor core characteristics than perifocal edema. In fewer published works on potential of using peritumoral edema in differential diagnostics between brain malignancies it is reported about distinctions of indicators in contrast-enhanced perfusion (DSC), bigger impact of cerebral blood flow volume (CBV) than velocity (CBF), diagnostic significance of CBF gradient in edema.

In our work we focus on studying peritumoral edema characteristics that could help in differentiating GBM and metastases.

Objectives:

• To calculate referenced indicators of cerebral blood flow volume and velocity according to MRI examinations of patients with GBM and metastases and evaluate accuracy of their differences
• To evaluate possibility of using differences in perifocal edema characteristics for differentiation between glioblastoma and metastases