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  • 1
    ISSN: 1432-1084
    Keywords: Magnetic resonance imaging ; Mechanical heart valves ; Deflection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract During in vitro tests, we exposed seven mechanical cardiac valves to a 1.5 Tesla magnetic field and measured their deflection and temperature changes during a gradient-echo sequence. We used a special suspension system which indicated and measured the largest deflection at the entrance to the tube and any deflections within the gradient field. A temperature sensor measured changes in temperature in the valve ring in both air and in a water bath during exposure to a high-frequency field. The Bjork-Shiley (Shiley Irvine, CA, USA) valve displayed the most deflection at the entrance to the coil, namely 1.8 mm. All the other valve models displayed less deflection. No deflection took place during gradient-echo sequences. Three valve models displayed an increase in valve ring temperature. The Medtronic valve displayed the largest increase with 0.6°C.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2161
    Keywords: Magnetic resonance imaging ; Soft tissues, magnetic resonance studies ; Muscles, neoplasms ; Juvenile fibromatosis, magnetic resonance studies ; Sedation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report the time-dependent magnetic resonance imaging (MRI) changes that resulted from an intramuscular injection of a commonly-used pediatric sedation regimen (“DPT”). These changes at the site of injection consist of a focal abnormality characterized by a slight increase in signal intensity on T1 weighted images and markedly increased signal intensity on T2 weighted images. Alterations in signal are detectable almost immediately after the injection and progress over the first 31 hours. This abnormality, which could be mistaken for real disease, persists up to 36 days following injection.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2102
    Keywords: Schlüsselwörter ; Koronare Herzkrankheit ; Magnetresonanztomographie ; Myokardperfusion ; SPECT ; Key words ; Coronary artery disease ; Magnetic resonance imaging ; Myocardial perfusion ; SPECT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Aim: Performance of combined rest/stress MR perfusion studies and the analysis of qualitative signal intensity parameters in comparison with 99mTc-SestaMIBI SPECT in patients with known coronary artery disease (CAD). Methods: Sixteen patients with CAD underwent MR myocardial perfusion assessment at rest and after dipyridamole-induced hyperemia. Qualitative parameters (SI increase, SI upslope) of the SI time-curves were evaluated and characteristics of normal, reversible and persistent hypoperfused myocardium as assessed by 99mTc-SestaMIBI SPECT were compared. Results: Compared with the rest values, normal myocardium showed a significant increase of the SI upslope during hyperemia (P〈0.001), whereas persistent (P=0.07) and reversible (P=0.15) hypoperfusions showed only minor changes. SI increase over baseline also showed a significant increase only in normal myocardium (P〈0.001). At rest, reversible ischemic areas showed no significant differences from normal myocardium, whereas during hyperemia SI increase was significantly lower (P=0.02). Conclusions: Qualitative SI parameters of a combined rest/stress MR myocardial perfusion study allow to differentiate normal from reversibly or persistently hypoperfused myocardium.
    Notes: Zusammenfassung Fragestellung: Die kombinierte Ruhe- und Belastungsuntersuchung der myokardialen Durchblutung in der MRT sowie die Analyse qualitativer SI-Parameter der MR-Myokardperfusion bei Patienten mit koronarer Herzkrankheit wurden mit der 99mTc-SestaMIBI SPECT verglichen. Methode: Bei 16 Patienten mit koronarer Herzkrankheit (KHK) wurde in der MRT mit einer Mehrschichtgradientenechotechnik die Myokardperfusion unter Ruhe- und Belastungsbedingungen untersucht. Qualitative Signalintensitätsparameter der Kontrastmittelanflutung wurden berechnet und die Parameter in normalen, reversibel und persistierend minderperfundierten Myokardarealen miteinander verglichen. Ergebnisse: Normales Myokard zeigte im Gegensatz zu reversiblen (P=0,15) und persistierenden (P=0,07) Ischämien eine signifikante Zunahme der SI-Anstiegssteilheit unter Belastung (P〈0,001). Die SI-Zunahme zeigte ebenfalls nur in normal perfundierten Arealen eine signifikante Zunahme (P〈0,001) nach Belastung. Unter Belastung zeigte sich bei reversiblen Ischämien eine signifikant niedrigere SI-Zunahme als in normalem Myokard (P=0,02), während sich in Ruhe kein Unterschied zeigte. Schlussfolgerung: Qualitative SI-Parameter der kombinierten MR-Perfusionsuntersuchung des Myokards in Ruhe und unter Belastung erlauben die Differenzierung zwischen normalem sowie reversibel oder persistierend minderperfundiertem Myokard.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2102
    Keywords: Schlüsselwörter Zerebrovaskuläre Erkrankung ; Arteriosklerose ; Magnetresonanztomographie ; Magnetresonanzangiographie ; Digitale Subtraktionsangiographie ; A. carotis ; Keywords Cerebrovascular disease ; Arteriosclerosis ; Magnetic resonance imaging ; Magnetic resonance angiography ; Digital subtraction angiography ; Carotid artery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Purpose. To compare high resolution contrast-enhanced MR angiography (MRA) and digital subtraction angiography (DSA) in the assessment of supraaortic vessel stenosis. Methods. 14 patients with suspicion of cerebrovascular disease or upper limb ischemia underwent selective DSA and high resolution contrast enhanced MRA employing a new Panoramic-Array coil. Stenosis assessment in comparison to DSA followed NASCET criteria. Additionally signal-/noise ratios (SNR) were evaluated to assess contrast enhancement. Results. Diagnostic image quality was achieved in all patients. Sensitivity and specificity for assessing high-grade stenosis of the supraaortic vessels were 100% and 96% respectively. In the assessment of high-grade common or internal carotid artery stenosis sensitivity and specificity was 100%. Conclusion. High resolution contrast enhanced supraaortic MRA combined with new coil sytems allow for a reliable assessment of stenoses along the whole vessel course including the aortic arch. Previous stent procedures limit its use in post-interventional follow-up.
    Notes: Zusammenfassung Fragestellung. Ziel der Studie war ein Vergleich zwischen hochauflösender kontrastverstärkter MR-Angiographie (MRA) und digitaler Subtraktionsangiographie (DSA) in der Diagnostik von Stenosen der supraaortalen Gefäße. Methoden. 14 Patienten mit Verdacht auf eine zerebrovaskuläre Erkrankung oder Durchblutungsstörung der oberen Extremität wurden mit DSA und hochaufgelöster, kontrastverstärkter MR-Angiographie mit Verwendung einer Panoramic-Array-Spule untersucht. Neben der Beurteilung der Kontrastierung erfolgte die Bestimmung der Stenosegrade im Vergleich zur selektiven DSA nach den NASCET-Kriterien. Ergebnisse. Bei allen Patienten konnte mit der MRA eine diagnostisch ausreichende Bildqualität erzielt werden. In der Diagnostik hochgradiger Stenosen der supraaortalen Gefäße ergab sich eine Sensitivität von 100% und eine Spezifität von 96%. In der Erkennung hochgradiger Stenosen der A. carotis communis oder interna lagen Sensitivität und Spezifität bei 100%. Schlussfolgerung. Die ultraschnelle MRA der supraaortalen Gefäße in Kombination mit einer geeigneten Spulenkombination ermöglicht die zuverlässige Erkennung stenotischer Veränderungen im gesamten Gefäßverlauf einschließlich des Aortenbogens. Stentimplanationen limitieren derzeit den Einsatz in der postinterventionellen Kontrolle.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 248 (1991), S. 151-155 
    ISSN: 1432-0711
    Keywords: Eclampsia complications ; Subdural effusion ; Meningeal thickening ; focal seizures ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 32-year-old primigravida showed signs of pre-eclampsia before delivery of a healthy boy at term. The CSF-space was accidentally punctured during epidural anaesthesia in labour. One day later hypertension was noted and the patient had a single generalized fit. For the next three weeks she had postural headaches, fluctuating hypertension, intermittent hearing loss and doublevision. On the 22nd day of postpartum, the patient had the first of a series of partial and later generalized seizures, followed by hemiparesis, alteration of consciousness, and finally slow recovery with corticosteroid therapy. Bilateral subdural effusions and generalized meningeal thickening were found on MR scans. Repeated MRI excluded sinus thrombosis and documented the response to treatment.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1459
    Keywords: Multiple sclerosis ; Interferon ; Cerebrospinal fluid ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A preliminary study is reported of clinical response and CSF/MRI findings in nine patients with multiple sclerosis receiving intravenous infusions of natural beta-interferon. The mean patient follow-up was for 1.2 years. Neither exacerbation rates nor CSF-IgG synthesis nor plaque formation as revealed by MRI showed a significant reduction during therapy. One patient developed a severe exacerbation of multiple sclerosis shortly after interferon infusion.
    Type of Medium: Electronic Resource
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