A new perfluorocarbon, PTBD (perfluoro-2,2,2',2'-tetramethyl-4,4'-bis(1,3-dioxolane)), is described for use in 19F MR imaging and spectroscopy. Two-thirds of the molecular fluorine in PTBD resonates at a single frequency and can be imaged without the use of frequency-selective spin-echo (SE) MRI pulse sequences to suppress chemical shift artifacts. The absence of strong homonuclear spin-spin coupling to the imagable -CF3 groups in PTBD minimizes signal attenuation in 19F SE MRI due to J-modulation effects. For equimolar concentrations of perfluorocarbon, PTBD gives an approximately 17% increase in sensitivity, relative to literature results for perfluorinated amines, at short values of TE (approximately 10 ms) in 19F SE MRI. These attributes allow 19F MRI of PTBD to be performed on standard clinical imaging instrumentation (without special hardware and/or software modification) and an in vivo example in a mouse is shown. This investigation involved characterizing the MR T1 and T2 relaxation times of PTBD as well as the MR spin-lattice relaxation rate, R1 (1/T1), of PTBD as a function of dissolved oxygen concentration. The T1 and T2 relaxation times and R1 relaxation rates of perfluorooctyl bromide (PFOB) were also obtained, under similar experimental conditions, to compare and contrast PTBD with a representative perfluorocarbon that has been widely employed for 19F MRI/MRS applications.
Aqueous solutions of an oligo(ethylene oxide)-n-perfluorooctyl ether with an average number of 16 ethylene oxide groups (abbreviated CFEO 16 ) were investigated. The phase diagram in the temperature composition plane qualitatively corresponds to the general behavior observed for oligo(ethylene oxide)-n-alkyl ether/ water mixtures. A series of light-scattering studies on isotropic solutions reveals enhanced scattered intensity with increasing temperature. Small angle neutron-scattering (SANS) experiments show this to be due to anisotropic micellar growth.
The title compounds (II), (IV), (V), (VII), and (IX) (together with its by‐product (X)) are synthesized by carefully controlled elemental fluorination of the substrates (I), (III), (VI), or (VIII).
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