Heterogeneity Diffusion Imaging of gliomas: Initial experience and validation.

Area of Science:

• Neuroimaging
• Oncology
• Medical Physics

Background:

• Primary brain tumors exhibit complex heterogeneity, including tumor cells, neural/glial tissues, edema, and vasculature.
• Conventional MRI techniques struggle to adequately assess these diverse pathological components and capillary blood perfusion.
• Accurate characterization is crucial for diagnosis, grading, and treatment planning of brain tumors.

Purpose of the Study:

• To introduce and evaluate Heterogeneity Diffusion Imaging (HDI), a novel diffusion MRI-based method.
• To assess HDI's capability in simultaneously detecting and characterizing multiple tumor pathologies and capillary blood perfusion.
• To compare HDI metrics with conventional MRI and dynamic susceptibility contrast (DSC) perfusion imaging in primary brain tumors.

Main Methods:

• Seven adult patients with primary brain tumors underwent both standard MRI protocols and the HDI protocol.
• Tumor sampling sites were correlated with imaging data for quantification.
• HDI-derived metrics were compared between World Health Organization (WHO) II and III tumor groups and correlated with DSC-derived cerebral blood volume (CBV).

Main Results:

• Conventional apparent diffusion coefficient did not differentiate between WHO II and III tumor groups.
• HDI revealed significantly elevated slow hindered diffusion fraction in WHO III tumors compared to WHO II.
• HDI-derived perfusion fraction and DSC-derived CBV were significantly higher in WHO III tumors; HDI perfusion fraction correlated strongly with DSC-CBV.

Conclusions:

• HDI offers superior accuracy and specificity over conventional apparent diffusion coefficient for brain tumor characterization.
• HDI can effectively separate and quantify tumor cell fraction, packing density, edema, and capillary blood perfusion.
• HDI shows significant promise for improved microenvironment characterization, noninvasive tumor grading, and biopsy planning.