Mitigating slice cross-talk in multi-slice multi-echo spin echo T₂ mapping.

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biomedical Engineering
• Medical Physics

Background:

• Multi-slice multi-echo spin echo (MESE) sequences are used for MRI.
• Accurate T2 mapping is crucial for various diagnostic applications.
• Potential for inter-slice variation in T2 quantification exists with standard methods.

Purpose of the Study:

• To investigate T2 inter-slice variation in multi-slice MESE imaging.
• To develop an enhanced T2 map reconstruction method to correct these variations.

Main Methods:

• Bloch simulations were used to model magnetization changes in multi-slice MESE sequences, considering direct saturation effects.
• Experimental phantom and in vivo scans validated the simulation results.
• A multi-slice dictionary-based reconstruction approach was developed using multi-slice echo modulation curves (EMCs).

Main Results:

• Direct saturation was shown to bias EMCs, leading to T2 inter-slice variations of up to 2.8% in vivo.
• Increasing the slice gap or repetition time (TR) reduced this variation.
• The proposed multi-slice dictionary method reduced the coefficient of variation (CV) to 0.54% in phantoms and 2.3% in vivo.

Conclusions:

• Standard T2 quantification from multi-slice MESE images using single-slice dictionaries is prone to bias.
• A dedicated multi-slice EMC method with appropriate dictionaries effectively minimizes inter-slice T2 variation.
• This enhanced method improves the accuracy of T2 mapping in multi-slice MRI.