3D-printable phantoms for quantitative dynamic contrast-enhanced MRI.

PURPOSE

A novel 3D-printed phantom design and methodology are proposed, addressing important requirements for technical validation, quality assurance, and multi-site harmonization of quantitative DCE-MRI measurements.

METHODS

Phantoms were produced by 3D-printing (3DP) gels incorporating channels and pores as proxies for blood vessels and extravascular extracellular space, respectively. A flow circuit was designed to reproduce clinically relevant arterial input functions. Using nine gels with variable porosity and channel size, we evaluated the effect of 3DP parameters on DCE-MRI parameters obtained using the extended Tofts model (ET). Physical gel and fitted model parameters were correlated by multiple linear regression.

RESULTS

All phantoms generated realistic arterial input functions, and tissue-like signal enhancement curves were accurately modeled by the ET model. As hypothesized, blood plasma volume fraction, v, was positively associated with the channel volume fraction, v, (B = 0.86, p < 0.001) and showed a weaker, negative association with gel porosity, v, (B = -0.18, p = 0.006). Vascular permeability-surface area product, PS, was positively associated with both v (B = 0.13 min, p < 0.001); and v (B = 0.051 min, p < 0.001). The extravascular extracellular space (EES) volume fraction, v, was positively associated with v (B = 0.90, p < 0.001) but not v. Fitted parameters were reproducible (coefficient of variation 2.1%-3.2%).

CONCLUSIONS

Tailorable 3D-printed porous gel phantoms generating tissue-mimicking DCE-MRI signals have the potential to support validation, quality assurance, and multi-site harmonization of quantitative DCE-MRI.