Berlin 2012 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

ST: Fachverband Strahlen- und Medizinphysik

ST 4: Poster

ST 4.4: Poster

Dienstag, 27. März 2012, 10:10–11:30, Poster F

Fast and Selective MRI of Xenon Biosensors — •Jörg Döpfert, Martin Kunth, Christopher Witte, Federica Rossella, and Leif Schröder — Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany

Due to its excellent chemical shift sensitivity and because its magnetization can be easily amplified by hyperpolarization, the use of xenon as a functionalized solution-state contrast agent (by trapping it in molecular cages such as cryptophane-A (CrA)) shows great promise. To further increase the signal, we detect Xe inside the cages indirectly by chemical exchange saturation transfer (Hyper-CEST).

However, imaging of the hyperpolarized nuclei remains challenging, since each excitation pulse followed by readout gradients depletes the hyperpolarization. Here, we employ single-shot echo-planar imaging (EPI) to encode a whole image with only one excitation.

We prepared a phantom consisting of two compartments containing CrA molecules (concentration: 10 µM) with a chemical shift separation of 1.2 ppm and imaged it by EPI combined with CEST presaturation (acquisition time: 19ms, saturation time: 4s). By setting the frequency of the saturation pulse to either of the two cage frequencies, we were able to distinguish the two CrA resonances and separately image their spatial distribution. The total acquisition time for one image was drastically reduced compared to the original approach using chemical shift imaging. The proposed method demonstrates the possibility of fast and selective imaging of highly specific functionalized agents in the micro molar regime.