An implantable synthetic SPECT lesion: A bridge from phantom to reality

Small-animal imaging systems are often characterized using phantoms, which may not predict performance in clinical applications. An implantable synthetic SPECT lesion would facilitate characterization of lesion detectability in a living animal. Methods: Anion-exchange columns with bed volumes of 100-300 nL were constructed from medical-grade polyvinyl chloride tubing and resin. The columns were tested in an excised mouse femur and implanted in the femur of a living mouse. Imaging was performed using a prototype dual-modality SPECT/CT system. Results: Activity of 7.4-22.2 MBq (0.2-0.6 mCi) localized within the synthetic lesion. The synthetic lesions were reused multiple times. Mice tolerated the implanted columns without complications for up to 8 wk. Conclusion: A reusable, synthetic SPECT lesion was constructed and implanted in the femur of a living mouse. The synthetic lesion is useful for the development of imaging schemes and for more realistically evaluating imaging-system performance in the context of a living animal.