Gerrit Hendrik van de Maat1, Hendrik de Leeuw1, Peter R. Seevinck1, Chris J.G Bakker2
1Image Sciences Institute, Utrecht, Netherlands; 2Department of Radiology, University Medical Center, Utrecht, Netherlands
It is feasible to excite protons that reside in the vicinity of Holmium loaded microspheres inside a voxel by shifting the center frequency f0 of the rf-excitation pulse. Due to this frequency shift, on-resonance protons are not excited and signal is only generated by protons strongly influenced by the dipole fields invoked by the microspheres. The total signal intensity of a voxel is related to the concentration HoMS in that voxel. The resulting positive contrast can be manipulated by the user since it will depend on the excitation bandwidth and profile and on the f0 frequency shift.