Validation of a quantitative susceptibility mapping acquisition and reconstruction pipeline using a new iron sucrose based MR susceptibility phantom

Abstract

PurposeQuantitative susceptibility mapping is a new technique and its processing pipeline has to be validated before clinical practice. We described an easy to build magnetic resonance (MR) susceptibility phantom based on iron sucrose. Materials and methodsIn a plastic container, Eppendorf tubes containing increasing iron sucrose concentration ranging from 0 to 60μg Fe/mL were inserted in an agarose gel. To estimate susceptibility, multiple coronal gradient echo acquisitions were performed with varying angle of the phantom relative to the B0 field, ranging from 30 to 90°. Quantitative susceptibility maps were reconstructed using the l1 and l2 norm of total variation using Split Bregman approach. Iron concentration was finally estimated from the susceptibility in the tubes. ResultsIn l1 norm susceptibility and estimated iron concentration were not different from the real values while l2 norm underestimated the susceptibility. A correlation was found between the angle of the phantom and the difference between real and estimated iron concentrations. The results highlight the importance of this validation by emphasizing the effects of various reconstruction parameters as well as acquisition conditions. Using optimal parameters, the quantitative susceptibility mapping provides a very good estimation of the iron concentrations in the phantom.