Mapping hepatic blood oxygenation by quantitative BOLD (qBOLD) MRI

Area of Science:

• Medical Imaging
• Hepatology
• Biophysics

Background:

• Hepatic oxygenation abnormalities indicate liver dysfunction and treatment response.
• Current MRI methods offer only semiquantitative hepatic oxygenation assessment.

Purpose of the Study:

• To propose and validate a quantitative BOLD (qBOLD) model for noninvasive mapping of hepatic venous blood oxygen saturation (Yv) and deoxygenated blood volume (DBV).
• To evaluate the model's validity and estimation bias using Monte Carlo simulations and human subject scans.

Main Methods:

• Development of a single-compartment hepatic qBOLD model.
• Monte Carlo simulations to assess model validity and estimation bias.
• Scanning of eight healthy human subjects using the developed qBOLD protocol.

Main Results:

• Simulations revealed deviations in T2* decay due to high hepatic blood volume fraction.
• Initial qBOLD model showed small bias for Yv and overestimation for DBV, correctable with calibration curves.
• Post-correction, mean hepatic Yv was 56.8 ± 6.8% and DBV was 0.190 ± 0.035, aligning with invasive methods.

Conclusions:

• The corrected hepatic qBOLD approach allows noninvasive, quantitative mapping of liver blood volume and oxygenation.
• This protocol can be utilized for assessing hepatic tissue hypoxia in various liver diseases.