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  • 1
    ISSN: 1619-7089
    Keywords: Positron emission tomography ; Cerebral glucose consumption ; Image resolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to investigate the influence of image resolution on (a) relative and absolute values of caudate glucose consumption (rCMRGIc) determined by positron emission tomography (PET), and (b) the detection of significant differences in these metabolic values between groups of subjects. For this purpose, raw data of cerebral accumulation of fluorine-18 fluorodeoxyglucose (FDG) obtained in 11 normal subjects and in nine patients with unilateral thalamic infarction were reconstructed using filtered backprojection with four different cut-off frequencies (CFs), yielding images with a transaxial resolution of 5.7, 7.1, 8.9 and 11 mm (full-width at half-maximum; FWHM). Absolute values of caudate rCMRGIc decreased significantly by more than 30% over the range of image resolutions studied. Bilateral ratios of caudate rCMRGIc were insensitive to variations in image resolution. Levels of significance assessing the differences in mean metabolic values between patients and controls were all below 0.01. They were, however, slightly better at image resolutions of 7.1 and 8.9 mm than at a resolution of 5.7 mm. These data indicate (a) that relative values of rCMRGIc are better suited to compare quantitative results from different PET cameras than are absolute values, and (b) that the CF used for the filtered back-projection exerts a small but not negligible influence on levels of significance assessing differences in metabolic values between groups of subjects.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European archives of psychiatry and clinical neuroscience 222 (1976), S. 191-207 
    ISSN: 1433-8491
    Keywords: Doppler-Sonography ; Carotid Occlusion ; Carotid Stenosis ; Localization of Stenosis ; Stroke ; Doppler-Sonographie ; Karotisverschluß ; Karotisstenose ; Stenoselokalisation ; Schlaganfall
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei 76 Patienten wurden die Ergebnisse der dopplersonographischen Untersuchungen der Karotiden am Hals mit denen der A. supratrochlearis und mit den angiographischen Kontrollen verglichen. Dabei zeigte sich, daß die direkte selektive Beschallung der Aa. carotis communis, interna und externa am Hals eine wesentliche Verbesserung gegenüber der indirekten Untersuchung nur der A. supratrochlearis erreicht. Diese läßt sich in drei Punkten zusammenfassen: 1. Die Häufigkeit falsch-positiver und falsch-negativer Befunde ist deutlich geringer als an der A. supratrochlearis. Von 76 angiographisch kontrollierten Fällen wurden bei der Untersuchung der Karotiden am Hals jeweils nur ein falsch-negativer und ein falsch-positiver Befund erhoben. Damit wird die diagnostische Zuverlässigkeit auf 97% erhöht. In diesem Kollektiv sind auch die mittelgradigen Stenosen (50% Lumeneinengung) enthalten. 2. Die Beschallung der Karotiden erlaubt die zuverlässige Differenzierung zwischen Stenose und Verschluß. Nur in einem Fall war diese nicht richtig. Durch Untersuchung der A. supratrochlearis allein ist diese Unterscheidung nicht möglich. 3. Die Lokalisation der Strömungsbehinderung gelang in allen Fällen. Diese Aussagen beziehen sich nur auf die Erfassung von Verschlüssen und mittel-bis höhergradigen Stenosen. Für die zuverlässige Diagnostik geringerer Stenosen (〈50% Lumeneinengung) ist die Methode ungeeignet.
    Notes: Summary The Doppler examination of the carotid arteries in the neck was compared with the results of the examination of the supratrochlear artery and of the angiographic controls in 76 patients. The results of this study indicate that the insonation of the carotid arteries considerably improves the diagnostic possibilities offered by the examination of the supratrochlear artery alone. 1. The reliability of the Doppler examination is improved. The insonation of the carotid arteries of the 76 angiographically controlled patients including stenoses from 50% onward gave only one false-positive and one false-negative result. The percentage of correct diagnoses thereby attained was 97%. 2. The insonation of the carotid arteries permits reliable differentiation between stenoses and occlusions. This is not possible by the insonation of the supratrochlear artery alone. There was only one case in which the distinction was wrong. 3. The localization of the pathologic process was possible in all cases. These conclusions are only valid for the detection of occlusions and stenoses of more than 50%. Low degree stenoses cannot be detected by this method.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1459
    Keywords: Creutzfeldt-Jakob disease ; Magnetic resonance imaging ; Putamen ; Globus pallidum ; Neuropathology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The history of a 67-year-old woman with histologically proven Creutzfeldt-Jakob disease (013) is presented. Before typical clinical and neurophysiological signs of CJD developed, magnetic resonance imaging (MRI) showed slightly enhanced signal intensity of the caudate nuclei and putamina in T2-weighted and proton density images, corresponding to spongiform degeneration in neuropathological examination. Five weeks later characteristical progressive cortical atrophy was demonstrated by follow-up MRI.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1459
    Keywords: Angiography ; Magnetic resonance imaging ; Ultrasonography ; Vertebral artery dissection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Spontaneous vertebral artery dissection (VAD) is a rare but well-known cause of cerebrovascular disease and is often difficult to diagnose even using conventional arteriography. While noninvasive tests such as Doppler ultrasonography and magnetic resonance imaging (MRI) have failed to provide reliable criteria for the diagnosis of VAD, the diagnostic value of magnetic resonance angiography (MRA) has not yet been undetermined. To establish the reliability of a combined noninvasive approach, 11 patients were prospectively examined for VAD by means of colour-coded duplex studies, MRI and three-dimensional time-of-flight MRA prior to conventional angiography. Among 11 patients with VAD suspected clinically as well as on Doppler ultrasonography, angiography confirmed the diagnosis in seven patients but found a vertebral artery occlusion in three and a vertebral artery stenosis in one. The combination of MRI and MRA findings led to the correct diagnosis of dissection in three patients, of vertebral artery occlusion in three patients, and of vertebral artery stenosis in one. VAD was misinterpreted as vertebral artery occlusion in four patients. Doppler ultrasonography is a valuable screening method for the detection of vertebral artery pathologies. The diagnosis of VAD can only be established if a typical intramural vessel wall haematoma is seen on T1-weighted MRI in combination with MRA findings of irregular artery stenosis or occlusion.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 244 (1997), S. 571-578 
    ISSN: 1432-1459
    Keywords: Key words Cerebral infarct ; Stroke aetiology ; Posterior cerebral ; artery ; Embolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Numerous reports have described a variety of clinical syndromes resulting from posterior cerebral artery (PCA) infarction, whereas only a few pathoanatomical and retrospective clinical studies have investigated the underlying mechanisms. Therefore we attempted to determine the causes of infarction in the superficial posterior cerebral artery (PCA) territory by means of a more comprehensive, modern vascular and cardiac study. During a 4-year period 74 consecutive patients (49 men, 25 women) with acute PCA infarction documented on CT (n = 74) and MRI (n = 41) were included in the study. Patients had a neurological examination, vascular studies [extra- and transcranial Doppler (n = 74), magnetic resonance (n = 31) or intra-arterial (n = 22) angiography], cardiac evaluation [ECG (n = 74), transthoracic (n = 74) and transoesophageal echocardiography (n = 30)], and coagulation tests. A cardiac source of embolism was established in 31%, significant vertebrobasilar artery disease in 22%, and PCA stenosis or occlusion in 8% of the patients. Rare causes, such as hypercoagulopathy or paradoxical embolism via a patent foramen ovale, were present in 15%. However, in spite of the comprehensive diagnostic evaluation, the cause of the stroke remained undetermined in 24% of the cases. Apart from complete infarcts of the posterior branches of the PCA, which occurred more frequently in cardioembolic strokes (18%, P 〈 0.05), the topographical patterns of infarct extension and the coincidence of infarction in the deep territories of the PCA, the cerebellum and brainstem were not significantly different among the causal subgroups. The frequency of haemorrhagic transformation (18%) was highest among cardioembolic strokes (44%, P 〈 0.001). This prospective study of PCA infarction demonstrated embolism from cardiac and vascular sources as the predominant cause. In contrast to previous studies, we found no evidence of migraine as a cause of PCA infarction, whereas paradoxical embolism was the presumed cause in a considerable number of cases. Whereas the cause of stroke could not reliably be derived from infarct topography, haemorrhagic transformation indicated there had been cardioembolism in most cases.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 243 (1996), S. 323-328 
    ISSN: 1432-1459
    Keywords: Stroke ; Carotid artery Dissection ; Cerebral embolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Because the pathogenesis of cerebral ischaemia in internal carotid artery dissection (ICAD) is controversial we studied the topography of cerebral infarction that results from ICAD according to pathophysiology of embolic and haemodynamic stroke. Sixty-four patients with 67 ICADs diagnosed by angiography, Doppler duplex sonography and magnetic resonance imaging (MRI) were studied prospectively during the past decade. According to current pathophysiological concepts, cortical territorial infarcts and large subcortical lenticulostriate infarcts revealed by CT or MRI were classified as embolic, while smaller infarcts in the subcortical junctional zone and infarcts in the cortical borderzone between the middle (MCA) and anterior cerebral artery were interpreted as haemodynamic infarcts. Of the 67 dissections 37 (55%) were associated with brain infarcts, of which territorial MCA infarcts of variable size accounted for 60%. These were combined with infarcts of the anterior and posterior cerebral artery in 5%; 8% of the patients had complete MCA infarction. Large lenticulostriate infarcts were present in 11%. Haemodynamic infarcts involved the subcortical junctional zone in 16% but never the anterior cortical borderzone. Although different abnormal Doppler findings indicated haemodynamically significant carotid obstruction in all symptomatic ICADs, only the characteristic high-resistance Doppler signal was significantly associated with the occurrence of brain infarction (in 66%,P 〈 0.01). The angiographic features of ICAD did not correlate with the incidence or with the topography of cerebral infarction. Patterns of infarction in ICAD indicate a predominantly embolic causation probably due to thrombus formation in the dissected carotid artery in the presence of severe haemodynamic obstruction, as demonstrated by Dopppler sonography.
    Type of Medium: Electronic Resource
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