Evaluation of low-grade glioma structural changes after chemotherapy using DTI-based histogram analysis and...

Area of Science:

• Neuroimaging
• Oncology
• Radiology

Background:

• Low-grade gliomas (LGGs) require monitoring during temozolomide (TMZ) chemotherapy.
• Assessing treatment response often relies on conventional MRI, which may show delayed changes.

Purpose of the Study:

• To investigate the utility of diffusion tensor imaging (DTI)-based histogram analysis and functional diffusion maps (fDMs) for evaluating structural alterations in LGGs during TMZ treatment.
• To determine if DTI metrics can detect early treatment effects before visible changes on standard MRI.

Main Methods:

• Twenty-one LGG patients underwent 3T-MRI, including DTI, before and after 3 and 6 cycles of TMZ.
• Histogram and fDM analyses were performed on DTI-derived metrics (mean diffusivity, fractional anisotropy, p, and q values).
• DTI changes were correlated with tumor volume, Response Assessment in Neuro-Oncology (RANO) criteria, and seizure response.

Main Results:

• All patients showed DTI changes after three TMZ cycles, preceding RANO criteria stability.
• DTI changes became more pronounced after six cycles.
• Early changes in DTI histogram percentiles (25th percentile of p and mean diffusivity) predicted final tumor volume changes.
• TMZ-induced alterations were primarily observed at tumor borders on p and MD fDMs.
• Early seizure response correlated with significant DTI value improvements.

Conclusions:

• DTI-based histogram and fDM analyses are valuable tools for assessing early temozolomide chemotherapy effects in LGG patients.
• These advanced DTI techniques offer a more sensitive method for monitoring treatment response compared to conventional MRI.
• Early DTI changes can predict treatment outcomes and correlate with clinical improvements, such as seizure control.