Mapping Intracellular Volume Fraction With Susceptibility Source Decomposition as a Marker for Tissue Cellularity

Area of Science:

• Radiology
• Neuroimaging
• Biomedical Engineering

Background:

• Pathophysiological changes significantly alter tissue cell composition and density.
• Conditions like neurodegenerative disorders and brain tumors involve cell loss or abnormal accumulation.
• Monitoring tissue cellularity can aid in clinical diagnosis and management.

Purpose of the Study:

• To introduce and validate the susceptibility-Derived Cellularity Index (χDCI) as a new MRI marker for tissue cellularity.
• To ensure the marker is readily available for clinical applications with fast acquisition and high resolution.

Main Methods:

• A retrospective study involving 24 healthy subjects and 21 glioblastoma patients.
• Utilized 3T MRI sequences including T1w, T2w, FLAIR, multi-echo GRE, and DWI.
• Computed χDCI using DECOMPOSE-QSM and estimated Neurite Density Index (NDI) with the NODDI model.

Main Results:

• Significant correlations between χDCI and NDI were found in white matter and putamen in healthy subjects.
• In glioblastoma patients, significant positive correlations were observed in white matter, pallidum, putamen, thalamus, and edema regions.
• These associations support χDCI's utility across different brain tissues and pathologies.

Conclusions:

• The susceptibility-Derived Cellularity Index (χDCI) is proposed as a novel marker for tissue cellularity.
• The observed significant associations between χDCI and NDI support its potential as a proxy for intracellular volume fraction.
• χDCI shows promise for clinical applications in assessing brain tissue cellularity.