Article
Physiological MRI biomarkers in the differentiation between glioblastomas and solitary brain metastases
Physiologische MR-Bildgebung zur Differenzierung von Glioblastomen und singulären Hirnmetastasen
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Published: | June 4, 2021 |
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Objective: Glioblastoma (GB) and solitary brain metastasis (BM) may appear similar in conventional magnetic resonance imaging (cMRI). Management strategies, however, are quite different with significant consequences on clinical outcome. The aim of this study was to evaluate the usefulness of a previously presented physiological MRI approach scoping to obtain quantitative information about microvascular architecture and perfusion, neovascularization activity, and oxygen metabolism to differentiate GB from BM.
Methods: Thirty-three consecutive patients with newly diagnosed, untreated, and histopathologically confirmed GB or BM were preoperatively examined with our physiological MRI approach as part of the cMRI protocol. For the analysis of tissue oxygen metabolism, we used the quantitative blood oxygen level depended (qBOLD) approach and for the neovascularization activity and microvascular architecture the vascular architecture mapping (VAM) approach. From the qBOLD data the oxygen extraction fraction (OEF), the cerebral metabolic rate of oxygen (CMRO2) and the tissue oxygen tension (PO2) were calculated. Likewise, from VAM the microvessel type indicator (MTI) for neovascularisation activity, the vessel size index (VSI) and the microvessel density (MVD) were derived. Furthermore, maps for cerebral blood flow (CBV) and microvascular perfusion (µCBV) were obtained.
Results: Physiological MRI biomarker maps revealed several significant differences in the pathophysiology of GB and BM: Central necrosis was more hypoxic in GB than in BM (30%; P = 0.036), which was associated with higher neovascularization activity (65%; P = 0.043) and metabolic rate of oxygen (48%; P = 0.004) in the adjacent contrast-enhancing viable tumor parts of GB. In peritumoral edema, GB infiltration caused neovascularization activity (93%; P = 0.018) and higher microvascular perfusion (30%; P = 0.022) associated with higher tissue oxygen tension (33%; P = 0.020) and lower oxygen extraction from vasculature (32%; P = 0.040).
Conclusion: Our physiological MRI approach, which requires only 7 minutes of extra data acquisition time, might be helpful to noninvasively distinguish GB and BM based on pathophysiological differences. However, further studies including more patients are required.