Contrast-free dynamic susceptibility contrast using sinusoidal and bolus oxygenation challenges

Area of Science:

• Neuroimaging
• Biophysics
• Medical Physics

Background:

• Dynamic susceptibility contrast (DSC) MRI typically relies on gadolinium contrast agents.
• Deoxygenation-based DSC (dDSC) MRI utilizes endogenous contrast from respiratory challenges, offering a gadolinium-free alternative.
• Assessing brain perfusion is crucial for diagnosing various neurological conditions.

Purpose of the Study:

• To compare the reliability of three different oxygen-based respiratory challenges for dDSC MRI.
• To evaluate the accuracy of perfusion estimates (CBF, CBV, MTT) derived from these dDSC methods.
• To assess the cross-modality correlation with traditional gadolinium-enhanced DSC MRI.

Main Methods:

• Ten healthy volunteers underwent dDSC MRI using three distinct respiratory challenges: desaturation, resaturation, and SineO2.
• Cerebral perfusion parameters including cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) were calculated.
• Tracer kinetics modeling was applied in the time domain (desaturation, resaturation) and frequency domain (SineO2).

Main Results:

• High correlations and agreement were found for CBV estimates across all three dDSC methods.
• Estimates for MTT and CBF showed variability depending on the specific hypoxic stimulus used.
• Cross-modality correlation with gadolinium DSC was moderate, particularly for MTT, but comparable to other perfusion references.

Conclusions:

• Oxygen respiratory challenges are feasible and reliable for measuring brain perfusion using dDSC MRI.
• While CBV estimates are consistent, CBF and MTT measurements are stimulus-dependent.
• Further research is needed to validate dDSC MRI for clinical applications in stroke, tumors, and neurodegenerative diseases.