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AbstractZiel: Entwicklung einer Prparationstechnik zum Nachweis von SPIO (superparamagnetic iron oxide) -haltigen Lsungen und SPIO-markierten Zellen mittels MRT ex-vivo. Detektion und Quantifizierung der magnetischen Markierung ber den Durchmesser der Signalauslschung in MR-Gradientenecho-Aufnahmen. Funktionale Beschreibung des Zusammenhangs zwischen lokaler Eisenkonzentration und Durchmesser der messbaren Signalauslschung fr die gewhlten Versuchsbedingungen. Untersuchung des Einflusses der Echozeit und der rumlichen Auflsung auf die Signalverteilung im MR-Tomogramm.Material und Methoden: Verwendung von Resovist, (SHU 555A) als superparamagnetisches Kontrastmittel. Einbringen von SPIO-haltigen Lsungen (0,75 15 mg Fe/10 ml) und SPIO-markierten SK-Mel28 Zellen (25.000 1.000.000 Zellen/10ml) in ein definiertes Volumen innerhalb einer Agar-Matrix. Messung des Durchmessers der Signalauslschung in Abhngigkeit von der lokalen Eisenkonzentration, der Echozeit (5-25 ms) und der rumlichen Auflsung (isotrop mit 0,25-0,60 mm Kantenlnge der Bildelemente) bei Verwendung einer 3D Gradientenechosequenz (FLASH) an einem klinischen 3 Tesla Ganzkrpertomographen.Ergebnisse: Die Ausdehnung der Signalauslschung im MR-Bild nahm mit geringerer Auflsung und lngerer Echozeit zu. Die Sensitivitt zum Nachweis der magnetischen Markierung war am grten bei TE 25 ms. Eine mglichst ortstreue Abbildung magnetisch markierter Bezirke konnte bei TE 5 ms und einer Auflsung von 0,25 mm erreicht werden. Der Durchmesser der Auslschung war eine logarithmische Funktion der lokalen Eisenkonzentration. Unter den gegebenen Messbedingungen konnten Konzentrationen ab 0,75 mg Fe/10ml (SPIO-haltige Lsung) bzw. 1,25 mg Fe/10ml (SPIO-markierte SK-Mel28 Zellen) sicher erfasst werden.Schlussfolgerungen: Die vorgestellte Prparationstechnik mit definierter Verteilung magnetischen Materials in einer Agar-Matrix zeigt sehr gut reproduzierbare und quantitativ verwertbare Ergebnisse und erscheint blichen Prparationen mit zuflliger Materialverteilung in Glasrhrchen berlegen.Purpose. This work aims to present a preparation technique for ex-vivo MR examination of SPIO (superparamagnetic iron oxide) containing solutions or SPIO labeled cells. Accumulations of SPIO particles and labeled cells were prepared in different concentrations using agar gel phantoms. Signal extinction around accumulations of magnetic material was examined systematically by gradient echo sequences with variable echo times and spatial resolution. The correlation between local iron concentration and diameter of signal extinction in MR gradient echo images was investigated.Methods. Resovist, (SHU 555A) was used as superparamagnetic contrast medium. Different concentrations of SPIO-containing solutions (0.75 15 mg Fe/10 ml) and magnetically labeled SK-Mel28 cells (25.000 1.000.000 cells/10 ml) were accommodated inside a defined volume in an agar matrix. Diameters of signal void were assessed in dependence on local iron concentration, echo time (5 25 ms) and isotropic spatial resolution (length of voxel 0.25 0.60 mm). Measurements were performed on a clinical MR whole body scanner (3 Tesla) using a spoiled gradient echo sequence (FLASH).Results. For the present experimental conditions sensitivity to detect the magnetic label was maximized using TE 25 ms. In contrast, the area of signal cancellation was minimized using TE 5 ms and isotropic resolution of 0.25 mm. In the latter case the image indicated the area of magnetic material most precisely. Diameter of signal cancellation was a logarithmic function on local iron concentration. In the presented set-up detection of concentrations as low as 0.75 mg Fe/10 ml in SPIO-containing solution or 1.25 mg Fe/10 ml in SPIO-labeled SK-Mel28 cells was certainly possible.Conclusion. The proposed preparation strategy with a well defined spatial distribution of the magnetic material in an agar gel phantom produced reliable results and appears clearly superior compared to set-ups with randomly distributed material in glass tubes. The diameter of the signal extinction in gradient echo images was significantly affected by the choice of echo time and spatial resolution. The calibration of signal cancellation versus iron concentrations may be valuable to assess SPIO concentrations and possibly numbers of labeled cells under specific conditions in vitro or even in vivo.

Noninvasive localized proton magnetic resonance spectroscopy (MRS) was used for differential diagnosis of a focal brain lesion in a 2.5-year-old girl. The clinical signs were a mild head tilt and neck pain. Magnetic resonance imaging (MRI) revealed a lesion in the right hemisphere of the cerebellum, but its nature remained obscure. In this lesion quantitative determinations of cerebral metabolites by fully relaxed, short-echo-time proton MRS revealed markedly lowered N-acetylaspartate (NAA) and pronounced elevations of choline-containing compounds (Cho) and myo-inositol (Ins), whereas metabolite concentrations in cortical gray matter and white matter were within normal ranges. The metabolite pattern of the lesion indicated loss of vital neuroaxonal tissue (low NAA) and enhanced glial proliferation (high Cho and Ins), which, together with the MRI morphology, suggested a brain tumor. The diagnosis was established by neurosurgical exploration and total extirpation of the tumor. Histology confirmed an astrocytoma (WHO II). After 2 weeks' recovery the child was discharged with no neurological signs.

In a patient with extrapyramidal movement disorder and extremely low creatinine concentrations in serum and urine, in vivo proton magnetic resonance spectroscopy disclosed a generalized depletion of creatine in the brain. Oral substitution of arginine, a substrate for creatine synthesis, resulted in an increase of brain guanidinoacetate as the immediate precursor of creatine but did not elevate cerebral creatine levels. In contrast, oral substitution of creatine-monohydrate led to a significant increase of brain creatine, a decrease of brain guanidinoacetate, and a nor-malization of creatinine in serum and urine. Phosphorus magnetic resonance spectroscopy of the brain revealed no detectable creatine-phosphate before oral substitution of creatine and a significant increase afterward. Partial restoration of cerebral creatine concentrations was accompanied by improvement of the patient's neurologic symptoms. This is the first report of a patient with complete creatine deficiency in the brain. Magnetic resonance spectroscopy during arginine and creatine treatment point to an inborn error of creatine biosynthesis at the level of guanidinoacetete-methyltransferase.

ABSTRACT: In a patient with extrapyramidal movement disorder and extremely low creatinine concentrations in serum and urine, in vivo proton magnetic resonance spectroscopy disclosed a generalized depletion of creatine in the brain. Oral substitution of arginine, a substrate for creatine synthesis, resulted in an increase of brain guanidinoacetate as the immediate precursor of creatine but did not elevate cerebral creatine levels. In contrast, oral substitution of creatine-monohydrate led to a significant increase of brain creatine, a decrease of brain guanidinoacetate, and a nor-malization of creatinine in serum and urine. Phosphorus magnetic resonance spectroscopy of the brain revealed no detectable creatine-phosphate before oral substitution of creatine and a significant increase afterward. Partial restoration of cerebral creatine concentrations was accompanied by improvement of the patient's neurologic symptoms. This is the first report of a patient with complete creatine deficiency in the brain. Magnetic resonance spectroscopy during arginine and creatine treatment point to an inborn error of creatine biosynthesis at the level of guanidinoacetete-methyltransferase.

Wide disparities existed in a rural community created by resettlement. Eight major problems were encountered