Superparamagnetic iron oxide nanoparticles (SPIONs) as a calibration and validation tool for QSM MRI sequences

Motivation: Progressing the clinical translation of QSM is important for imaging of biometal dysregulation in neurodegenerative disease but available methods for calibrating QSM sequences between systems are limited. Goal(s): To develop and validate a superparamagnetic iron oxide nanoparticle (SPION) phantom replicating human brain iron concentration. Approach: Dilutions of Ferrotrace SPION (0.1-25 $$$\mu$$$g/mL) were scanned with research application QSM gradient echo sequence using two different 3T systems and multiple analysis methods. Results: A good linear fit was demonstrated between QSM values and SPION concentration across a clinically relevant interval and different QSM analysis methods. Values differed between two scanners but there was high within-scanner concordance. Impact: A SPION based phantom replicating in vivo iron of healthy and diseased brain could be an invaluable calibration and QA tool for QSM clinical translation, normative datasets and emerging SPION-based theranostics for brain cancer.