An anatomically correct 3D‐printed mouse phantom for magnetic particle imaging studies

Abstract

We report anatomically correct 3D‐printed mouse phantoms that can be used to plan experiments and evaluate analysis protocols for magnetic particle imaging (MPI) studies. The 3D‐printed phantoms were based on the Digimouse 3D whole body mouse atlas and incorporate cavities representative of a liver, brain tumor, and orthotopic breast cancer tumor placed in anatomically correct locations, allowing evaluation of the effect of precise doses of MPI tracer. To illustrate their use, a constant tracer iron mass was present in the liver for the breast (200 μgFe) and brain tumor (10 μgFe) model, respectively, while a series of decreasing tracer iron mass was placed in the tumor region. MPI scans were acquired in 2D and 3D high sensitivity and high sensitivity/high resolution (HSHR) modes using a MOMENTUM imager. A thresholding algorithm was used to define regions of interest (ROIs) in the scans and the tracer mass in the liver and tumors was calculated by comparison of the signal in their respective ROI against that of known mass fiducials that were included in each scan. The results demonstrate that this approach to image analysis provides accurate estimates of tracer mass. Additionally, the results show how the limit of detection in MPI is sensitive to the details of tracer distribution in the subject, as we found that a greater tracer mass in the liver cavity resulted in poorer sensitivity in tumor regions. These experiments illustrate the utility of the reported 3D‐printed anatomically correct mouse phantoms in evaluating methods to analyze MPI scans and plan in vivo experiments.

Recent Developments in Magnetic Hyperthermia Therapy (MHT) and Magnetic Particle Imaging (MPI) in the Brain Tumor Field: A Scoping Review and Meta-Analysis

“…3D Printed Mouse Phantom for MPI To aid in the optimization of future MPI studies, Sarna et al [47] engineered an anatomically relevant mouse phantom with several hollow organ-representative cavities generated from the Digimouse atlas. The brain cavity contained a tumor simulacron, as well as two capillary tubes used for SPION delivery.…”

Inter-user comparison for quantification of superparamagnetic iron oxides with magnetic particle imaging across two institutions highlights a need for standardized approaches

“…It is essential that these fiducials are imaged using the same parameters, including selection field gradient strength and excitation amplitude and frequency, as these factors contribute to MPI signal strength. These fiducials may be included with the subject within the imaging field of view (FOV) [20][21][22][23], which we refer to as "internal calibration". The added benefit of internal fiducials is they can serve as benchmarks for co-registration with other imaging modalities (e.g., optical images acquired prior to a scan, computed tomography, magnetic resonance imaging, etc.).…”