Various numerical phantoms with a given fat fraction, T2* and field map were designed. The k-space of numerical phantoms was converted into RF signals to generate virtual phantoms. MRI experiments were performed at 4.7 T using a multi-gradient-echo sequence on virtual and physical phantoms. The data acquisition of virtual and physical phantoms was simultaneous. Decomposition of the water and fat signals was performed using a complex-based water–fat separation algorithm.
Overall, a good agreement was observed between the fat fraction, T2* and phase map values of the virtual and numerical phantoms. In particular, fat fractions of 10.5 ± 0.1 (vs 10% of the numerical phantom), 20.3 ± 0.1 (vs 20%) and 30.4 ± 0.1 (vs 30%) were obtained in virtual phantoms.
The ViP MRI method allows for generating imaging phantoms that i) mimic water–fat systems and ii) can be analyzed with water–fat separation algorithms based on complex data.