A novel editing technique for 19F MRI: Molecule-specific imaging

Abstract

A novel technique is proposed to facilitate the selective imaging of specific molecules from a mixture. The application of the technique presented here demonstrates the ability to selectively produce 19F MR images of either trifluoroacetic acid or the perfluorocarbon emulsion Oxypherol-ET (perfluorotributylamine), when both molecules are present simultaneously. Selective detection is based on the presence of homonuclear J-modulation in one molecule and differential spin-spin relaxation time ( T 2). Perfluorotributylamine, an A 3B 2 system, is subject to homonuclear J-modulation, which produces a null signal from the antiphase components of the triplet (A 3) when an echo time (TE) = 1 2J is used in a spin-echo image. At this echo time the second molecule, in this example trifluoroacetic acid, a non-coupled spin system, is selectively imaged. At longer echo times, e.g., TE = 1 J there is substantial recovery of the J-modulated signal, which may be solely observed due to T 2 decay of the trifluoroacetic acid signal. The method is demonstrated both using phantoms and in vivo.