Quantitative proton density mapping: correcting the receiver sensitivity bias via pseudo proton densities

Area of Science:

• Medical Imaging
• Neuroimaging
• Biophysics

Background:

• Proton density (PD) mapping in brain tissue is crucial for MRI analysis.
• Existing PD mapping methods often require accurate receiver coil profiles (RP), which are difficult to measure.
• Previous methods attempted RP compensation using bias field correction on spoiled gradient echo data.

Purpose of the Study:

• To present and validate an independent method for proton density (PD) mapping in brain tissue.
• To utilize the linear relationship between longitudinal relaxation rate (R1) and 1/PD for accurate mapping.
• To compare the proposed method with bias field correction techniques across healthy subjects and various brain pathologies.

Main Methods:

• Developed an independent PD mapping method based on the R1 and 1/PD relationship.
• Acquired data at 3 Tesla field strength.
• Compared the new method's results with bias field correction methods in healthy controls and patients with multiple sclerosis, stroke, meningioma, and recurrent glioblastoma.

Main Results:

• The independent method generated comparable RP and PD maps to bias field correction in healthy subjects.
• Quantitative PD values from the new method closely matched established literature values.
• Both PD mapping methods were evaluated across diverse neuropathological conditions.

Conclusions:

• The R1-based method provides a robust and independent approach for proton density (PD) mapping.
• This new method offers accurate PD quantification and is validated in both healthy and diseased brain tissues.
• The findings support the utility of this independent method for clinical and research neuroimaging applications.