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  • 1
    ISSN: 0942-0940
    Keywords: Keywords: Pituitary adenoma; vascular endothelial growth factor; Ki-67; cavernous sinus.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary  Surgical cure of growth hormone producing pituitary adenomas (GHomas) becomes difficult when they invade the cavernous sinus (CS). Tumour proliferative activity and angiogenesis are thought to be required for tumour growth and invasion, and vascular endothelial growth factor (VEGF) activates neovascularization around tumours. In this study, the mechanism and clinical significance of CS invasion is analysed. In 25 surgically treated GHomas, the extent of CS invasion was classified as high (Knosp's grade 3 and 4), and low (grade 0, 1 and 2) MR grades, and the MR grades were compared with tumour proliferative potential (Ki-67 expression), angiogenetic demand (VEGF expression), volume of adenomas and serum hormone levels.  The Ki-67 index of high MR grade adenomas (1.17±0.62%) was significantly higher than that of low MR grade adenomas (0.55±0.42%, p=0.027), whereas VEGF expression showed no significant correlation with MR grades (p〉0.999). Tumour volume also showed a significant correlation with MR grade (p=0.002). VEGF expression was not correlated with serum hormone level and volume, but was correlated with tumour proliferative potential. Proliferative potential and tumour volume were two independent factors related to CS invasion. Although VEGF expression was not a direct factor related to CS invasion, it may indirectly play a role in activation of tumour aggressiveness, which is required in CS invasion.  Our results show that high MR grade adenomas have higher proliferative ability. In order to improve the surgical outcome, pre-operative medical debulking is indicated, particularly, in such adenomas.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 140 (1998), S. 779-786 
    ISSN: 0942-0940
    Keywords: Keywords: Collagen; magnetic resonance imaging; pituitary adenoma; transsphenoidal surgery.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary  The transsphenoidal approach is a less invasive and safer procedure for removing pituitary adenomas. However, this procedure becomes extremely difficult when the tumour consistency is fibrous as encountered in about 10% of pituitary adenomas. In this study, we investigated predicting factors of tumour consistency in magnetic resonance images (MRIs).  MRIs of two groups, twenty-one soft and five firm (fibrous) adenomas, were retrospectively evaluated and compared in respect of tumour consistency. To compare the two groups objectively, tumour densities on MRI films and percentage of collagen content on operative specimens were expressed as numerical data using NIH-imageTM. The relationships between collagen content and T1-weighted images, T2-weighted images, grade of enhancement effect, and heterogeneity of enhancement were investigated.  Signal intensities on T1-weighted images were not correlated with tumour consistency, whereas those on T2-weighted images were significantly correlated with the percentage of collagen content. Adenomas, showing lower signal intensities on T2-weighted images, contained more collagen. On enhanced images, homogeneously enhanced adenomas tended to include more collagen, even though the grade of enhancement effect showed only weak correlation with the tumour hardness.  MRIs give us useful information on tumour consistency. Adenomas may be firm and fibrous if they show low signal intensities on T2-weighted images and homogeneous enhancement. To remove such tumours, a long sized and small-calibred ultrasonic aspirators applicable to transsphenoidal approach must be prepared and multi-staged operations may be more than likely needed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 2843-2847 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An apparatus of the radiometric emissivity measurement of a metal has been developed. The apparatus possesses some features that it can keep a metallic sample under specific conditions such as vacuum, oxidizing, and deoxidizing atmosphere. Using the apparatus, spectral (from visible to 10 μm infrared wavelengths), directional (normal and 80°), and polarized emissivities (p and s polarized) of metals can be measured and can be utilized to investigate the behavior of the emissivity of the specimen. In this article, the concrete design of the apparatus is described and some examples of measurements of emissivities under some specific conditions are introduced. The peculiar behaviors of the emissivity of a metal in the early stage when the oxide film is grown on its surface are discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Crystal Growth 117 (1992), S. 54-57 
    ISSN: 0022-0248
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Crystal Growth 107 (1991), S. 621-625 
    ISSN: 0022-0248
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Crystal Growth 93 (1988), S. 750-754 
    ISSN: 0022-0248
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1920
    Keywords: Key words Pituitary ; adenoma ; Growth hormone-secreting ; Acromegaly ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Preoperative serum growth hormone (GH) level is one of the most important determinants of outcome. Our aim was to assess MRI findings which may correlate with pretreatment GH levels in GH-secreting adenomas. We retrospectively studied 29 patients with acromegaly caused by a pituitary adenoma. Tumor size (height, width, thickness and volume), suprasellar extension, sphenoid or cavernous sinus invasion, signal intensity and contrast enhancement were studied. Linear regression analysis or Fisher's exact probability test was used for statistical analysis. Factors related to high GH levels were the maximum dimension of the tumour (r = 0.496, P 〈 0.01), its volume (r = 0.439, P 〈 0.05), spenoid sinus invasion (P 〈 0.01) and intracavernous carotid artery (encasement (P 〈 0.01). The other items were not related to serum GH levels. Since we believe surgery is the first choice of treatment and the cavernous sinus is difficult of access with a conventional surgical approach, preoperative assessment of invasion into the cavernous sinus is critical for predicting the surgical outcome. Low GH levels (5–50 ng/ml) were found with tumours medial to the intercarotid line and high levels (more than 101 ng/ml) with invasive tumours with carotid artery encasement. Variable GH levels were noted with tumours extending beyond the intercarotid line. Because functioning adenomas invading the cavernous sinus tend to have markedly high hormone levels, and only patients with carotid artery encasement showed markedly elevated GH levels, we believe carotid artery encasement a reliable MRI indicator of cavernous sinus invasion.
    Type of Medium: Electronic Resource
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