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PubMed · 7891530

Ultra-rapid gradient echo imaging.

O Heid·M Deimling·W J Huk
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Abstract

A novel ultra-rapid gradient echo (URGE) NMR imaging technique is introduced, which is capable of continuous high resolution 3D scanning while neither subject to fast gradient switching nor excessive RF power deposition. Sampling free induction decays instead of creating spin echoes enables maintaining a workable steady state magnetization. Due to segmented k-space acquisition, chemical shift, diffusion, and field inhomogeneity effects do not present major problems. We report on implementations acquiring from 32 x 64 x 64 partial-Fourier image sets in 0.72 s, allowing for single-shot magnetization-prepared 3D imaging, to 128 x 128 x 128 image sets in 13.3 s and 21.5 s on a standard MRI scanner.

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ArtifactsBrainFourier AnalysisHumansImage Processing, Computer-AssistedMagnetic Resonance ImagingSignal Processing, Computer-AssistedTime FactorsJournal Article

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BibTeXRIS

O Heid, M Deimling, W J Huk. 1995. Ultra-rapid gradient echo imaging.. https://doi.org/10.1002/mrm.1910330123

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PubMed1998

Rapid determination of methadone and its major metabolite in biological fluids by gas-liquid chromatography with thermionic detection for maintenance treatment of opiate addicts.

A rapid gas-liquid chromatographic assay is developed for the quantification of methadone (Mtd) and its major metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), in biological fluids of opiate addicts. After alkaline extraction from samples with lidocaine hydrochloride as internal standard, Mtd and EDDP are separated on SP-2250 column at 220 degrees C and detected with a thermionic detector. The chromatographic time is about 6 min. The relative standard deviations (R.S.D.) of Mtd and EDDP standards are between 1.5 and 5.5%. Most drugs of abuse (morphine, codeine, narcotine, cocaine, benzoylecgonine, cocaethylene, dextropropoxyphene etc) are shown not to interfere with this technique. The method has been applied to study the levels of Mtd and EDDP metabolite in serum, saliva and urine of patients under maintenance treatment for opiate dependence. EDDP levels were found higher than those of Mtd in urine samples from four treated patients, but lower in serum and undetectable in saliva. However, Mtd concentrations were higher in saliva than in serum.

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