SMUPhantom: A 3D-printable modular CT perfusion phantom for quantitative evaluation of tissue-mimicking dynamic contrast behavior

PURPOSE: Physical computed tomography (CT) perfusion (CTP) phantoms are useful for controlled protocol evaluation, but a modular 3D-printable platform that can generate distinguishable compartment-specific dynamic contrast behavior and support repeatability assessment remains needed. We developed the Separate Module Uniting Phantom (SMUPhantom) for protocol sensitivity studies and workflow benchmarking. METHODS: The SMUPhantom consists of three modules representing inflow, exchange, and outflow regions. Polyoxymethylene (POM) beads, soft wax, and acrylonitrile-butadiene-styrene (ABS) inserts were used to create healthy, penumbra-mimicking, and infarct-core-mimicking pathways, and a detachable bypass-flow pathway was added for flow-routing experiments. Two experimental series were performed on a NeuViz Epoch Elite CT scanner: contrast volume and injection rate were varied separately, each with and without bypass flow. Time-density curves (TDCs) and workstation-derived cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time to peak (TTP) were evaluated. Five repeat measurements per condition assessed intra-scanner repeatability. RESULTS: The three compartments showed separable dynamic responses, with the healthy pathway exhibiting earlier and higher enhancement and the infarct-core-mimicking pathway showing lower and delayed responses. Increasing contrast volume broadened the bolus response and raised peak enhancement from 220.8 to 454.2 HU in the healthy pathway and from 149.4 to 354.4 HU in the infarct-core-mimicking pathway, whereas increasing injection rate shortened TTP from 22-25 s to 12-15 s and MTT from 18-21 s to 10-14 s. Opening bypass flow modified the compartment curves and map appearance, particularly in the infarct-core-mimicking pathway, while preserving interpretable trends across repeated scans. Repeatability analysis showed stable peak enhancement and cerebral blood volume measurements, with CVs not exceeding 3.54% and 2.81%, respectively. CONCLUSION: SMUPhantom provides a 3D-printable and quantitatively characterized platform for CTP protocol sensitivity studies, repeatability assessment, and workflow benchmarking under controlled flow-routing conditions.