Relationship between Apparent Diffusion Coefficients and MR Spectroscopy Findings in High-Grade Gliomas

Area of Science:

• Neuroradiology
• Oncology
• Biomedical Imaging

Background:

• The correlation between apparent diffusion coefficient (ADC) and cellularity in high-grade gliomas (HGG) is debated.
• Hypoxia and necrosis, indicated by magnetic resonance spectroscopy (MRS) metabolites, may influence ADC values.

Purpose of the Study:

• To investigate differences in ADC values between HGG areas with and without MRS markers of hypoxia and necrosis.
• To clarify the relationship between diffusion parameters and tumor microenvironment in HGG.

Main Methods:

• Retrospective review of MRS datasets and ADC maps from 28 HGG patients.
• Regions of interest (ROIs) were placed on ADC maps based on spectral characteristics (lactate, lipids, or neither).
• Statistical analysis (ANOVA/Welch test) compared ADC metrics (Mean ADC, minADC, ADC SD) across ROIs.

Main Results:

• Minimum ADC (minADC) values were significantly higher in lactate-expressing regions (LAC group) compared to regions without metabolites (NEG group).
• No other significant differences in ADC metrics were found between groups.
• P = .03 indicated statistical significance for the minADC difference.

Conclusions:

• HGG areas with MRS markers of hypoxia and necrosis are not associated with restricted diffusion.
• A trend towards diffusion facilitation was observed in lactate-expressing HGG regions.
• Hypoxia-induced glioma cell volume reduction and extracellular water shift may explain facilitated diffusion.