Mechanical Properties of Glioblastoma vs. Non-Tumor Brain Tissue

Overview

This study investigated the mechanical differences between glioblastoma (GBM) and adjacent non-tumorous brain tissue using indentation testing. Findings demonstrated that GBM tissue exhibits distinct elasticity and stress-relaxation characteristics compared to healthy brain tissue, potentially aiding intraoperative tumor delineation.

Background

Glioblastoma multiforme (GBM) is a highly malignant and invasive primary brain tumor with poor prognosis despite multimodal treatment including surgery, radiotherapy, and chemotherapy. Surgical resection aims for maximal tumor removal while preserving healthy and eloquent brain areas, but distinguishing tumor from normal tissue intraoperatively remains challenging. Mechanical properties such as tissue elasticity and viscosity contribute to tactile differentiation during surgery. This study focused on quantifying these properties in GBM and adjacent non-tumorous brain tissue to enhance neurosurgical decision-making.

Data Highlights

19 patients with GBM (10 initial, 9 recurrent) provided tumor and non-tumorous brain samples. Mechanical indentation measured elasticity and stress-relaxation immediately after resection. Tumor samples contained >60% tumor cells; non-tumorous samples were confirmed tumor-free histologically. The Mach-1 v500c® device applied a 0.3 g load via a 1 mm cylindrical indenter at 0.1 mm/s, holding deformation for 30 seconds to assess viscoelastic behavior.

Key Findings

• GBM tissue exhibits higher stiffness (elastic modulus) compared to adjacent non-tumorous brain tissue.
• Stress-relaxation behavior differs between tumor and healthy tissue, reflecting altered viscoelastic properties in GBM.
• Mechanical differences correlate with tumor microenvironment changes, including extracellular matrix stiffening.
• Surgeons’ intraoperative tactile assessment sometimes misclassified tissue, highlighting the value of objective mechanical measurements.
• Immediate ex vivo testing avoided desiccation artifacts, ensuring reliable mechanical property assessment.
• Mechanical testing may complement existing intraoperative tools to improve tumor margin identification.

Clinical Implications

Quantitative assessment of mechanical properties can provide neurosurgeons with objective data to distinguish GBM from healthy brain tissue intraoperatively, potentially improving resection accuracy. Incorporating mechanical testing alongside current imaging and fluorescence techniques may reduce residual tumor and preserve functional brain areas. This approach supports more precise surgical planning and may enhance patient outcomes.

Conclusion

Mechanical characterization of GBM and adjacent brain tissue reveals significant differences in elasticity and viscoelasticity that can aid intraoperative tumor identification. These findings support the integration of mechanical property assessment into neurosurgical practice to improve resection precision.

References

1. Glioblastoma incidence and prognosis references [22, 27, 29, 33]
2. Neurosurgical techniques and multimodality references [4, 12, 13, 18, 21, 24, 26, 31, 34, 37, 39, 42]
3. Brain tissue elasticity and viscoelasticity references [7, 8, 9, 10, 40]
4. Tumor microenvironment and extracellular matrix stiffening references [3, 20, 25, 38]
5. Ethics Committee University of Luebeck, AZ 19-319