Development of a human-tissue-like phantom for 3.0-T MRI

Purpose: A 3.0-T MRI phantom having human-tissue-equivalent relaxation times was developed. Methods: The ingredients of the phantom are carrageenan (for gelatinization), GdCl₃ (as a T₁-relaxation modifier), agarose (as a T₂-relaxation modifier), and NaN₃ (as an antiseptic agent). Numerous samples with varying concentrations of GdCl ₃ and agarose were prepared, and T₁ and T₂ were measured using 3.0-T MRI. Results: Relaxation times of the phantom samples ranged from 395 to 2601 ms for T₁ values and 29 to 334 ms for T ₂ values. Based on the measured results, empirical formulae were devised to express the relationships between the concentrations of relaxation modifiers and relaxation times. Conclusions: Adjustment of GdCl₃ and agarose concentrations allows arbitrary setting of relaxation times, and the creation of a phantom that can mimic relaxation times of human-tissue. Carrageenan is considered the most suitable as a gelling agent for an MRI phantom, as it permits the relatively easy and inexpensive production of a large phantom such as for the human torso, and which can be easily shaped with a knife.