A single-scan T2* mapping method based on two gradient-echo images with compensation for macroscopic field...

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Quantitative Imaging
• Biomedical Engineering

Background:

• Conventional T2*-weighted imaging (T2*WI) and T2* mapping suffer from signal loss due to macroscopic field inhomogeneity.
• Existing z-shimming methods mitigate inhomogeneity but significantly increase imaging time.
• There is a need for faster T2* mapping techniques that maintain accuracy in the presence of field variations.

Purpose of the Study:

• To develop a fast T2* mapping method that compensates for macroscopic field inhomogeneity.
• To maintain the sensitivity of T2* signal to microscopic susceptibility changes.
• To achieve this without extending the total acquisition time compared to conventional methods.

Main Methods:

• A novel fast T2* mapping technique was developed.
• It utilizes a proton density-weighted image and a composite T2*-weighted image for T2* calculation.
• The composite image is reconstructed from gradient-echo images with incremental z-shimming compensation acquired in a single scan.

Main Results:

• The proposed method generates T2* maps free from macroscopic field inhomogeneity-induced signal loss.
• The total acquisition time is comparable to conventional multiecho gradient-echo sequences without compensation.
• Performance and efficiency were successfully demonstrated and evaluated at 4.7 Tesla.

Conclusions:

• The developed fast T2* mapping method effectively compensates for macroscopic field inhomogeneity.
• This technique offers an efficient solution for quantitative T2* mapping without prolonged scan times.
• The method holds promise for improved MRI applications requiring accurate T2* measurements.