Altered Perivascular Diffusivity in Glioblastoma:Integrating DTI-ALPS Index with Radio-Pathomicand Histopathologic...

Area of Science:

• Neuroscience
• Radiology
• Oncology

Background:

• Glioblastoma (GBM) is an aggressive brain tumor characterized by perivascular invasion.
• Perivascular invasion may disrupt the brain's glymphatic system, impairing fluid drainage.
• The Diffusion Tensor Imaging-Along the Perivascular Space (DTI-ALPS) index is a potential MRI biomarker for glymphatic function.

Purpose of the Study:

• To assess glymphatic dysfunction in glioblastoma patients using the DTI-ALPS index.
• To correlate MRI-derived tumor features with radio-pathomic maps of hypercellularity.
• To investigate the relationship between glymphatic function and patient survival.

Main Methods:

• Analysis of 368 IDH-wildtype GBM patients from the UCSF-PDGM dataset.
• Preprocessing of preoperative MRI scans (T1, T1C, FLAIR, ADC, DTI).
• Generation of radio-pathomic maps of tumor cellularity and computation of the DTI-ALPS index.

Main Results:

• The DTI-ALPS index was significantly lower in the tumor-affected hemisphere (ipsilateral side) for both gross total resection (GTR) and subtotal resection (STR) cohorts.
• Lower DTI-ALPS index correlated inversely with contrast-enhancing and FLAIR hyperintensity volumes and tumor cellularity.
• Autopsy analysis confirmed tumor cells in perivascular spaces, and lower DTI-ALPS index was associated with significantly worse overall survival.

Conclusions:

• GBM-associated perivascular invasion significantly disrupts glymphatic function, as evidenced by reduced DTI-ALPS index.
• The extent of GBM-induced perivascular fluid dynamic alteration correlates with tumor volume and cellularity.
• Impaired glymphatic function, indicated by a lower DTI-ALPS index, is a negative prognostic factor for glioblastoma patients.