Off-Resonance Spin Echos for Probing the Cellular Microenvironment
Cunningham C, Conolly S, Yang P, McConnell M, Suzuki Y, Pauly J, Chen I, Gambhir S
A new pulse sequence consisting of spectral-spatial excitation/refocusing pulses and an optional oscillating readout gradient was developed for obtaining positive contrast when imaging regions of concentrated superparamagnetic iron oxide (SPIO). It was demonstrated that the resulting signal can carry information such as the local phase distribution surrounding the cells, which could be used for iron quantification. Also, a proof-of-principle experiment showed that information about a complementary contrast agent such as Gd-DTPA can be measured in the positive contrast signal. This interaction can be measured at a high rate because localization is provided entirely by the RF pulses.