In Brief | Critical Care, Anaesthesia & Emergency Medicine | Gerontology
Metformin's Effect on Glioblastoma Hypoxia: Insights from qBOLD MRI Analysis
Time to read: 05:08
Time to listen: 11:02
Originally Published: 2 December 2024
Source: European Radiology Experimental
Type of article: In Brief
MedED Catalogue Reference: MRDIB001
Category: Radiology & Imaging
Cross Reference: Oncology, Neurology
Keywords: qBOLD imaging, glioma, metformin, oncology, neurology, hypoxia
Overall, qBOLD imaging offers insights into glioma oxygen metabolism, with metformin showing promise in modulating hypoxia progression.
Specifically:
This article is a review of recent studies originally published in the European Radiology Experimental, 2 December 2024. This article does not represent the original research, nor is it intended to replace the original research. Access the full Disclaimer Information.
Study Purpose
This study aims to validate the qBOLD technique’s accuracy in assessing tumour hypoxia in a malignant glioma-bearing rat model, correlating its findings with pathological results. Additionally, the study seeks to investigate dynamic changes in glioma oxygenation using qBOLD measurements, both with and without metformin administration.
Study Methodology
The study included 13 C6-bearing Wistar rats and 3 healthy Wistar rats. A total of seven tumour-bearing and three healthy rats underwent 7-T qBOLD MRI to assess oxygen extraction fraction (OEF) and cerebral metabolic rate of O2 (CMRO2).
Findings
The following findings were recorded:
qBOLD-based O2 Metabolism in Healthy Rats
As the tumour progressed, T2, T2*, and CBV decreased, OEF increased, and CMRO2 declined. In the metformin group, T2 and T2* values were significantly higher than controls on day 15, but no differences were seen by day 18. OEF remained lower, and CMRO2 decreased significantly compared to controls by day 18.
Discussion
This study explores changes in oxygen metabolism during glioma progression by analyzing qBOLD parameters in both healthy and glioma-bearing models. It examines the correlation between qBOLD measurements and hypoxia markers, tracks longitudinal alterations in tumour oxygenation, and assesses the impact of metformin on glioma metabolism.
These findings show that tumour tissues share physical characteristics with grey matter but exhibit lower oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2), indicating inefficient metabolism and a preference for aerobic glycolysis. While no correlation was found between HIF-1α and pimonidazole expression, pimonidazole levels were inversely associated with T2 and T2* values, suggesting these parameters may serve as markers of chronic hypoxia.
As tumours progress, they shift from acute cyclic hypoxia to chronic diffusion-limited hypoxia. This study supports Andreas’s classification of glioma oxygen metabolism but suggests a continuous metabolic evolution rather than discrete states.
Metformin treatment maintained higher T2 and T2* values, with lower OEF and CMRO2, indicating a potential role in delaying tumour hypoxia.
Conclusion
Importance of this study for South Africa
However, a recent study published in 2024 examined brain tumours in the Western Cape, highlighting important trends in tumour types and patient demographics. The study included 505 patients with brain tumours, with a mean age at diagnosis of 44 years (range: 0–82 years). Notably, 16% of primary tumours occurred in individuals under 20 years old. 2
Gliomas, glioneuronal and neuronal tumours, meningiomas, and pituitary tumours were the top four primary tumour types. Secondary brain tumours, making up 18% of cases, were most commonly associated with lung and breast cancers.
The study also revealed distinctive findings when compared to international registries, with a higher proportion of ependymal tumours and fewer nerve sheath tumours in South Africa.
This underscores the importance of advanced imaging techniques, such as those discussed in this study, as part of future efforts to better understand and manage brain tumours in South Africa.
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Additional References
1. Kelly, A., Lekgwara, P., & Mda, S. (2020). The epidemiology and outcome of patients admitted for elective brain tumour surgery at a single neurosurgical centre in South Africa. Surgical Neurology International, 11(2214751920302139). https://www.sciencedirect.com/science/article/pii/S2214751920302139
2. Basson, D., Schutte, C., van Coller, R., et al. (2024). Brain tumours in the Western Cape Province of South Africa: A plea for a dedicated brain tumour registry in Africa. World Journal of Clinical Medicine, 6(2), 53–60. https://doi.org/10.18772/26180197.2024.v6n2a1
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