Targeted radiofrequency field mapping using 3D reduced field-of-view-catalyzed double-angle method

Purpose

The aim of this study was to develop a targeted volumetric radiofrequency field (B₁⁺) mapping technique to provide region-of-interest B₁⁺ information.

Materials and Methods

Targeted B₁⁺ maps were acquired using three-dimensional (3D) reduced field-of-view (FOV) inner-volume turbo spin echo-catalyzed double-angle method (DAM). Targeted B₁⁺ maps were compared with full-FOV B₁⁺ maps acquired using 3D catalyzed DAM in a phantom and in the brain of a healthy volunteer. In addition, targeted volumetric abdomeninal B₁⁺ mapping was demonstrated in the abdomen of another healthy volunteer.

Results

The targeted reduced-FOV images demonstrated no aliasing artifacts in all experiments. Close match between targeted B₁⁺ map and reference full-FOV B₁⁺ map in the same region was observed, with percentage root-mean-squared error <0.4% in the phantom and <0.8% in the healthy volunteer brain. The abdominal B₁⁺ maps showed small B₁⁺ variation in the kidneys and liver from the healthy volunteer.

Conclusion

The proposed 3D reduced-FOV catalyzed DAM provides a rapid, simple and accurate method for targeted volumetric B₁⁺ mapping and can be easily implemented for applications related to radiofrequency field mapping in small targeted regions.