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Abstract #0525

Facilitated Detection and Quantification of Theragnostic Magnetocapsules by Analyzing MRI Susceptibility Perturbations

Parker H. Mills1,2, Thomas Link3, Aravind Arepally3, Joseph D. Thompson4, Jeff W.M. Bulte3, Eric T. Ahrens1,2

1Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA; 2Pittsburgh NMR Center for Biomedical Research, Pittsburgh, PA, USA; 3Institute for Cell Engineering, Johns Hopkins School of Medicine, Baltimore, MD, USA; 4Division of Materials Science & Technology, Group 10, Los Alamos National Laboratory, Los Alamos, NM, USA

Non-invasive studies have monitored the delivery and engraftment of pancreatic islets encapsulated in alginate shells containing Feridex, an FDA-approved superparamagnetic iron-oxide (SPIO). These magnetocapsules are permeable to metabolites, but not native antibodies, thus reducing or avoiding immunosuppressive therapy. Here we apply a newly developed post-processing method, Phase map cross-correlation Detection and Quantification (PDQ), to gel phantoms containing ~103, 450 μm diameter magnetocapsules. PDQ automatically identified and counted magnetocapsules, accurately measuring their magnetic moment (within 1-21% of SQUID-measured values). PDQ can potentially search tissue volumes for absolute magnetocapsule numbers, providing insight on overall islet immunoprotection and survival. PDQ requires no special pulse sequences and works on previously-acquired data.