Authors (including presenting author) :
Xiao L(1), Kwan KK(1), Leung HY(1), Dennis Ngar(1)
Affiliation :
(1)Clinical Oncology, Tuen Mun Hospital
Introduction :
The homogeneity of static magnetic field (B0) is a key factor in modern MRI scanner applications. It is important to evaluate the field homogeneity. In clinical setting, the verification is quite challenging. The purpose of the project is to create and assess multi-vendor protocols utilized simple phantom based on a homemade Python analysis program.
Objectives :
1. To evaluate the feasibility of different protocols proposed by vendors and researchers; 2. To compare and assess the parameters effects on the evaluation of field homogeneity; 3. To set up one clear guideline for the usage of the protocols and baseline for local equipment
Methodology :
Different methods including spectral linewidth methods, the bandwidth-difference methods, field map methods and phase-difference methods were used to identify the B0 field homogeneity. Especially for field map and phase-difference method, different echo time were set and tested for the parameter dependence evaluation of the B0 field homogeneity. Python program were applied for unwrapping phase images and analyzing phase information to calculate field homogeneity from any two echoes and monitor the B0 field homogeneity with different diameters of spherical volume (DSV).
Result & Outcome :
According to our experience and study, both field map and phase-difference method provide versatile and comprehensive result. The feasible and reproducible outcome for the evaluation of the B0 field homogeneity is good enough to use as the baseline for both methods. It is recommended to use any of them as the methods to evaluate the B0 field homogeneity. Phase-difference is preferred due to other factors effects on the homogeneity could be excluded. Even without the phase unwrap program, it is also able to generate the final result based on these two methods.
