Imaging phantoms are used to calibrate and validate the performance of magnetic
resonance imaging (MRI) systems. Many new materials have been developed for additive
manufacturing (three-dimensional [3D] printing) processes that may be useful in the
direct printing or casting of dimensionally accurate, anatomically accurate,
patient-specific, and/or biomimetic MRI phantoms. The T1, T2, and T2* spin relaxation
times of polymer samples were tested to discover materials for use as tissue mimics and
structures in MRI phantoms. This study included a cohort of polymer compounds that was
tested in cured form. The cohort consisted of 101 standardized polymer samples
fabricated from: two-part silicones and polyurethanes used in commercial casting
processes; one-part optically cured polyurethanes used in 3D printing; and fused
deposition thermoplastics used in 3D printing. The testing was performed at 3 T using
inversion recovery, spin echo, and gradient echo sequences for T1, T2, and T2*,
respectively. T1, T2, and T2* values were plotted with error bars to allow the reader to
assess how well a polymer matches a tissue for a specific application. A correlation was
performed between T1, T2 , T2* values and material density, elongation, tensile
strength, and hardness. Two silicones, SI_XP-643 and SI_P-45, may be usable mimics for
reported liver values; one silicone, SI_XP-643, may be a useful mimic for muscle; one
silicone, SI_XP-738, may be a useful mimic for white matter; and four silicones,
SI_P-15, SI_GI-1000, SI_GI-1040, and SI_GI-1110, may be usable mimics for spinal cord.
Elongation correlated to T2 (p = 0.0007), tensile strength correlated to T1 (p = 0.002),
T2 (p = 0.0003), and T2* (p = 0.003). The 80 samples not providing measurable signal
with T1, T2, T2* relaxation values too short to measure with the standard sequences, may
be useful for MRI-invisible fixturing and medical devices at 3 T.