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  • 1
    Electronic Resource
    Electronic Resource
    Echo planar perfusion imaging with high spatial and temporal resolution: methodology and clinical aspects (1999)
    Springer
    European radiology 9 (1999), S. 221-229 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Perfusion-weighted MRI ; Cerebral perfusion ; Parameter images ; Cerebrovascular disease ; Brain tumours
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The purpose of the present study was to analyse specific advantages of calculated parameter images and their limitations using an optimized echo-planar imaging (EPI) technique with high spatial and temporal resolution. Dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) was performed in 12 patients with cerebrovascular disease and in 13 patients with brain tumours. For MR imaging of cerebral perfusion an EPI sequence was developed which provides a temporal resolution of 0.68 s for three slices with a 128 × 128 image matrix. To evaluate DSC-MRI, the following parameter images were calculated pixelwise: (1) Maximum signal reduction (MSR); (2) maximum signal difference (ΔSR); (3) time-to-peak (Tp); and (4) integral of signal-intensity-time curve until Tp (SInt). The MSR maps were superior in the detection of acute infarctions and ΔSR maps in the delineation of vasogenic brain oedema. The time-to-peak (Tp) maps seemed to be highly sensitive in the detection of poststenotic malperfused brain areas (sensitivity 90 %). Hyperperfused areas of brain tumours were detectable down to a diameter of 1 cm with high sensitivity ( 〉 90 %). Distinct clinical and neuroradiological conditions revealed different suitabilities for the parameter images. The time-to-peak (Tp) maps may be an important advantage in the detection of poststenotic “areas at risk”, due to an improved temporal resolution using an EPI technique. With regard to spatial resolution, a matrix size of 128 × 128 is sufficient for all clinical conditions. According to our results, a further increase in matrix size would not improve the spatial resolution in DSC-MRI, since the degree of the vascularization of lesions and the susceptibility effect itself seem to be the limiting factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003300050659
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    3D MR angiography with ramp-shaped flip-angle distribution (1996)
    Springer
    European radiology 6 (1996), S. 489-493 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00182478
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Three-dimensional chemical shift-selective MRI of a ruptured intracranial dermoid cyst (1996)
    Springer
    Neuroradiology 38 (1996), S. 572-574 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00626102
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Three-dimensional chemical shift-selective MRI of a ruptured intracranial dermoid cyst (1996)
    Springer
    Neuroradiology 38 (1996), S. 572-574 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00626102
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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