Olivier Maciej Girard1, Jiang Du1, Robert Frederick Mattrey1
1Department of Radiology, University of California, San Diego, CA, USA
Superparamagnetic iron oxide (SPIO) nanoparticles are efficient contrast agents for molecular and cellular MR imaging. They are usually considered to be negative contrast agents due to their strong T2* effect, but they also have intrinsic T1 shortening properties that can produce positive contrast using appropriate MR pulse sequences. In the present study Utrashort TE (UTE) sequences were used to demonstrate the positive contrast even at high iron concentrations. Saturation Recovery prepared UTE sequences revealed an efficient contrast pattern. In addition to the usual T2* contrast it is possible to use the T1-signature of SPIO agents to improve detection specificity and localization.