DREAM--a novel approach for robust, ultrafast, multislice B₁ mapping

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Medical Physics
• Radiology

Background:

• Accurate B₁-field mapping is crucial for quantitative MRI.
• Existing methods are often slow, limiting their clinical applicability.
• Faster B₁-mapping can improve imaging efficiency and enable new applications.

Purpose of the Study:

• To introduce a novel, rapid multislice B₁-mapping technique.
• To evaluate the accuracy and performance of the proposed method.
• To demonstrate its utility in in vivo human imaging.

Main Methods:

• Development of the dual refocusing echo acquisition mode (DREAM) technique.
• Utilizing a Stimulated Echo Acquisition Mode (STEAM) preparation followed by a gradient echo sequence.
• Simultaneous measurement of STEAM and gradient echoes to determine flip angles.

Main Results:

• Achieved whole transmit coil volume coverage in one second, over ten times faster than conventional methods.
• Method is insensitive to susceptibility/chemical shift effects and provides B₀ and transceive phase maps.
• Demonstrated low T₁/T₂ dependence and low specific absorption rate (SAR).
• Validated accuracy through phantom experiments and in vivo imaging on abdomen, legs, and head.

Conclusions:

• The dual refocusing echo acquisition mode (DREAM) offers a significantly faster and accurate B₁-mapping solution.
• Its robustness and efficiency make it suitable for advanced MRI applications, including radiofrequency shimming.
• The method shows promise for routine clinical use, enhancing quantitative MRI capabilities.