Clinical Scorecard: Modified Perivascular Diffusivity in Glioblastoma: Combining DTI-ALPS Metrics with Radiopathomic and Histopathological Associations

At a Glance

Key Highlights

• GBM rapidly proliferates and resists therapy with median survival of 14.6–20.9 months despite standard care.
• The glymphatic system facilitates brain waste clearance via perivascular spaces; dysfunction may worsen tumor microenvironment.
• DTI-ALPS index quantifies water diffusivity along perivascular spaces and serves as a noninvasive marker of glymphatic function in GBM.

Guideline-Based Recommendations

Diagnosis

• Use multiparametric MRI (T1, T1 post-contrast, FLAIR, ADC, DTI) for tumor characterization and segmentation.
• Apply radio-pathomic machine learning models on mpMRI to estimate tumor cellularity and infiltration beyond contrast-enhancing regions.
• Calculate DTI-ALPS index from diffusion tensor imaging to assess glymphatic function alterations ipsilateral and contralateral to tumor.

Management

• Integrate imaging biomarkers including DTI-ALPS and radio-pathomic maps to better delineate tumor infiltration and microenvironment changes.
• Consider glymphatic dysfunction as a factor in tumor progression and therapeutic resistance.

Monitoring & Follow-up

• Monitor changes in DTI-ALPS indices over time to evaluate perivascular fluid dynamics and potential glymphatic impairment.
• Use radio-pathomic maps to track tumor cellularity and infiltration beyond conventional imaging boundaries.

Risks

• Tumor infiltration beyond contrast-enhancing margins may be underestimated without advanced imaging techniques.
• Glymphatic dysfunction may contribute to accumulation of toxic metabolites exacerbating tumor microenvironment.

Patient & Prescribing Data

368 adult patients with pathologically confirmed IDH-wildtype glioblastoma from UCSF Preoperative Diffuse Glioma MRI dataset

Standard of care therapy yields limited survival; imaging biomarkers like DTI-ALPS and radio-pathomic maps provide insights into tumor infiltration and glymphatic alterations that may inform future therapeutic strategies.

Clinical Best Practices

• Standardize DTI-ALPS ROI placement using template-based normalization to ensure reproducible glymphatic function measurements.
• Combine multiparametric MRI with radio-pathomic machine learning models for comprehensive assessment of tumor cellularity and infiltration.
• Incorporate both ipsilateral and contralateral hemisphere DTI-ALPS indices to evaluate spatial glymphatic alterations relative to tumor location.

References

• WHO Classification of Tumors of the Central Nervous System, 2021
• UCSF Preoperative Diffuse Glioma MRI Dataset
• SPM12 Software for Image Registration
• Advanced Normalization Tools (ANTs)
• Liu et al. Method for DTI-ALPS Computation