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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European radiology 6 (1996), S. 489-493 
    ISSN: 1432-1084
    Keywords: MR angiography (MRA) ; Ramp-shape excitation pulse ; Carotid arteries ; Vertebral arteries ; MR pulse sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This study addressed the use of 3D MR angiography with flip angles (FAs) linearly varying across the excitation volume in order to diminish spin saturation. The shape of the ramp profile was varied to optimize the method for different regions and pathological alterations. Radio frequency pulses with ramp-shaped excitation profiles were generated flow-compensated 3D-FISP sequence. With the use of ramp-shaped excitation profiles good results were obtained for intracranial arteries as well as for neck arteries (i.e. carotid and vertebral arteries) which were demonstrated in 6 healthy volunteers and in 5 patients with various stenoses and anomalies of the carotid and vertebral arteries. With this technique it was possible to use increased thicknesses of the excitation volume (slab) up to 256 mm. Ramp-shaped excitation pulses with linearly increasing FAs in main flow direction can provide improved contrast of the vessel parts located distally to the entry side of the slab. Although this method has no advantage concerning complex flow or other dephasing effects; its particular effectiveness lies in the reduction of spin saturation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1920
    Keywords: Key words Intracranial dermoid cyst ; 3D chemical-shift-selective imaging ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a man with a ruptured intracranial dermoid cyst, suffering from headache, nausea, vomiting and a generalised seizure. MRI was performed before and 2 weeks after surgical resection. On T 1-weighted images the tumour gave high signal, as did fatty material in the frontal and parietal brain sulci. Identification of this hyperintense material as lipids was possible by chemical-shift-selective 3 D gradient-echo imaging, which provided excellent contrast between the subarachnoid lipids and the adjacent normal brain, with a good spatial resolution. Possible complications of subarachnoid and intraventricular lipid particles after dermoid cyst rupture are discussed and the diagnostic value of 3 D chemical-shift-selective additional to conventional T 1-weighted spin-echo images in identification of even small amounts of fat is emphasised.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1920
    Keywords: Intracranial dermoid cyst ; 3D chemical-shift-selective imaging ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a man with a ruptured intracranial dermoid cyst, suffering from headache, nausea, vomiting and a generalised seizure. MRI was performed before and 2 weeks after surgical resection. On T1-weighted images the tumour gave high signal, as did fatty material in the frontal and parietal brain sulci. Identification of this hyperintense material as lipids was possible by chemical-shift-selective 3 D gradient-echo imaging, which provided excellent contrast between the subarachnoid lipids and the adjacent normal brain, with a good spatial resolution. Possible complications of subarachnoid and intraventricular lipid particles after dermoid cyst rupture are discussed and the diagnostic value of 3 D chemical-shift-selective additional to conventional T1-weighted spin-echo images in identification of even small amounts of fat is emphasised.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
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