Metabolic Imaging as Future Technology and Innovation in Brain-Tumour Surgery: A Systematic Review

Area of Science:

• Neurosurgery
• Oncology
• Radiology
• Metabolic Imaging

Background:

• Standard neurosurgical imaging struggles to detect infiltrative tumor regions beyond contrast enhancement.
• Metabolic imaging with hyperpolarized 13C-MRI offers potential for enhanced intraoperative insights into brain tumor biology.

Purpose of the Study:

• To systematically evaluate clinical and technical evidence of hyperpolarized MRI for metabolic characterization of malignant brain tumors.
• To assess the utility of hyperpolarized 13C-MRI in perioperative and diagnostic settings for brain tumor patients.

Main Methods:

• Systematic review of original human studies on hyperpolarized 13C-MRI in brain tumor patients.
• Inclusion criteria focused on perioperative and diagnostic applications, excluding reviews, animal studies, and technical reports.
• Methodological quality assessed using QUADAS-2; data synthesized qualitatively and via meta-analysis where feasible.

Main Results:

• Three studies (15 patients) met inclusion criteria.
• Significant difference in bicarbonate-to-pyruvate ratio between tumor and non-tumor brain (SMD = 1.34, p = 0.002).
• Pyruvate-to-lactate ratio (kPL) showed minimal difference (SMD = 0.06, p = 0.730) and a small effect between tumor and white matter (SMD = -0.33); high heterogeneity (I² = 69.4%).

Conclusions:

• Hyperpolarized 13C-MRI demonstrates metabolic differentiation between tumor and healthy brain tissue, especially via bicarbonate metabolism.
• The technology shows promise for metabolic tumor characterization.
• Further clinical validation is essential before routine intraoperative application in neurosurgery.