A USPIO doped gel phantom for R2* relaxometry.

MAGMA

Translational Research Centre, The University of Queensland, St Lucia, Australia.

Published: February 2017

Objective: This work describes a phantom containing regions of controlled R2* (1/T2*) values to provide a stable reference object for testing implementations of R2* relaxometry commonly used for liver and heart iron assessments.

Materials And Methods: A carrageenan-strengthened gadolinium DTPA doped agarose gel was used to enclose nine gels additionally doped with ultra-small superparamagnetic iron oxide. R2* values were determined at 1.5 T using multi-echo GRE sequences and exponential regression of pixel values from a region of interest against echo time using non-linear regression algorithms. We measured R2*, R2 and R1 values and the inter-scan and inter-operator reproducibility.

Results: The phantom reliably demonstrated R2* values in seven steps between 22.4 s (SE 1.98) and 441.9 s (SE 6.76), with an R2* relaxivity (r2*) of 792 (SE 5.6) mM s. The doped gels displayed a concentration-dependent R2' component of R2* phantom, indicating superparamagnetic enhancement effects. We observed no significant change in relaxivity (r2*) over 12 months, and estimate a useful life of 3 years. Detailed descriptions of the production process and calculators are been provided as Online Resources.

Conclusion: The phantom provides a durable test object with controlled R2* relaxation behaviour, useful for a range of R2* relaxometry reference work.

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http://dx.doi.org/10.1007/s10334-016-0576-xDOI Listing

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