International Journal on Magnetic Particle Imaging IJMPI
Vol. 12 No. 1 Suppl 1 (2026): Int J Mag Part Imag
https://doi.org/10.18416/IJMPI.2026.2603028

Proceedings Articles, ID 948

In vivo MPI of HER2-targeted tumor SPIO uptake is hindered by its current dynamic signal range

Main Article Content

Asif Itoo (1The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA 2Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA), Ali Shakeri-Zadeh (Johns Hopkins University), Janani Gurumurthy (1The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA 2Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA), Preethi Korangath (3Department of Radiation Oncology and Molecular Radiation Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD, USA), Sudath Hapuarachchige (1The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA), Dmitri Artemov (1The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA 2Cellular Imaging Section and Vascular Biology Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA), Robert Ivkov (3Department of Radiation Oncology and Molecular Radiation Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD, USA), Jeff Bulte (1The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, The Johns Hopkins University School of Medicine, Baltimore, MD, USA)

Copyright (c) 2026 Asif Itoo, Ali Shakeri-Zadeh, Janani Gurumurthy, Preethi Korangath, Sudath Hapuarachchige, Dmitri Artemov, Robert Ivkov, Jeff Bulte

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This work is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

Trastuzumab (Tz, herceptin) is a clinically approved monoclonal antibody targeting HER2 on tumor cells, making it an attractive bioligand for specific tumor targeting of superparamagnetic iron oxide (SPIO) nanoparticles. We investigated if Tz-conjugated SPIO could be used for MPI of HER2+ breast tumors. Successful conjugation and preservation of specific HER2-binding of Tz after SPIO conjugation was confirmed in vitro by immunostaining and MPI. Following intravenous injection of Tz-SPIO in a transgenic (spontaneously orthotopic) HER2+ breast cancer mouse model, in vivo MPI was unable to show a distinguishable tumor signal due to the close anatomical proximity of high-signal organs (i.e., liver, spleen, and lungs) to the thoracic tumor, unlike in subcutaneous models. The pulmonary signal disappeared by day 3, indicating SPIO redistribution and/or clearance. However, ex vivo MPI confirmed that tumor accumulation of Tz-SPIO was approximately 1.7- to 3.7-fold higher than that for IgG1-SPIO and unconjugated-SPIO controls, respectively. We conclude that the limited dynamic range of the current MPI technology prevents successful in vivo tumor visualization at low tumor to non-tumor tissue ratios, which was 1:8 to 1:15 in our studies. While antibody-mediated SPIO tumor targeting works in principle, there is an urgent need to develop methods for increasing the dynamic range of MPI.

Article Details

References

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