Modular breast and tumor perfusion phantoms for 4D dynamic contrast-enhanced dedicated breast CT

Tumor heterogeneity presents significant challenges in breast cancer diagnosis and treatment. Four-dimensional dynamic contrast-enhanced dedicated breast CT (4D DCE-bCT) is a novel imaging technique designed to capture contrast agent kinetics with high spatial and temporal resolution, enabling detailed assessment of tumor perfusion and heterogeneity.

To develop modular breast tumor phantoms capable of simulating a range of physiologically relevant perfusion patterns and structural heterogeneities for validation of 4D DCE-bCT.

Tumor phantoms (1.5 cm diameter) were 3D-printed using clear resin in several designs: small-channel phantoms (0.8 and 1.0 mm diameter), a leaking vessel model with permeable outer walls, gyroid structures (1.3 and 1.5 mm pores) mimicking microvascularization, and a dual-input/output model to replicate heterogeneous perfusion. The phantoms were integrated into a programmable flow system, enabling iodinated contrast (up to 5 mg I/mL) delivery with custom profiles: full wash-in/wash-out, persistent, plateau, and partial wash-out. 4D DCE-bCT acquisitions with a 65 kV + 0.25 mm Cu filter involved 1 pre-contrast scan (360 pulses over a 10-second revolution at 80 mA) followed by three post-contrast phases (400 pulses over 10 revolutions at 32 mA). Images were reconstructed using 40 projections at 5-second intervals using prior image constrained compressed sensing (PICCS). Time-intensity curves (TICs) were analyzed in volumes of interest in various sections of the tumor phantoms. A gamma variate function was fitted to each TIC, and the corresponding fit parameters and coefficients of determination (R²) were extracted.

Dynamic imaging demonstrated successful capture of expected contrast kinetics. Larger channels (1.0 mm) produced 2.5 times greater enhancement compared to smaller ones (0.8 mm). The R² values for the 0.8 mm and leaking channel were lower, 0.54 and 0.67 versus 0.85 in the 1 mm channel, due to a higher noise level in the signal. The leaking vessel phantom exhibited delayed wash-out by ∼30 s. Distinct flow patterns were evident in the dual-input/output model. The gamma variate parameters showed the expected trends due to the programmed flow patterns.

The developed 3D-printed tumor phantoms effectively simulate key perfusion features and point towards the feasibility of using 4D DCE-bCT to image detailed perfusion patterns.