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    Keywords: CELLS ; DISEASE ; MRI ; SEQUENCE ; pancreatic neoplasms ; PANCREATIC ENDOCRINE TUMORS ; Hyperinsulinism ; Insulinoma ; CT studies ; ISLET-CELL TUMORS
    Abstract: PURPOSE: Insulinomas are rare tumors that originate from the islet cells of the pancreas. The aims of this study were to localize insulinomas preoperatively using CT and/or MRI in correlation with postoperative pathological results. PATIENTS AND METHODS: Between December 2001 and June 2010, 27 consecutive patients with clinically suspected insulinoma were surgically treated in our university hospital. Preoperative CT (14 of 27 patients) and MRI studies (14 of 27 patients, one patient had both MRI and CT), operation reports, intraoperative ultrasonography reports, and pathological diagnoses were analyzed retrospectively. For each lesion, images were analyzed based on the presence of enhancement or the characteristics of signal intensities. Pathologic correlation was available for all the lesions. RESULTS: The female: male ratio was 2.9, with a mean age of 47.5 years (range 12-82) . Preoperative tumor localization was achieved by means of MRI and CT. A focal pancreatic lesion, which was hypointense on T(1)-weighted sequences, was detected on all the MR images (14 of 27 patients; 100%). These lesions were isointense (4 cases) to slightly hyperintense (10 of 14 cases) on T(2)-weighted sequences. In T(1)-weighted fat-suppressed contrast-enhanced sequences, there were two types of enhancement: homogeneously hyperintense lesions (in 10 of 14 cases) or peripherally hyper-, centrally isointense (in 4 of 14 cases). On all the CT images (14 of 27 patients), there was no detectable lesion on precontrast series; on arterial series in 13 of 14 patients (arterial series has not been done in one patient), lesions enhanced hypervascular in contrast to the rest of the pancreas with a mean enhancement of 147 HU (range 113-248) and 95 HU (range 65-141), respectively. On venous series in 13 of 14 patients (venous series has not been done in one patient), there was an enhanced lesion in contrast to the rest of the pancreas with a mean enhancement of 110 HU (range 91-151) and 86 HU (range 65-137), respectively. Intraoperative ultrasonography was performed in 11 of 27 patients to localize the tumor, which correlated with the results of the mentioned preoperative studies. Tumor size ranged from 9 x 11 to 31 x 37 mm. Enucleation was carried out in 14 patients, Whipple in 5, segmental resection in 3 and left distal pancreatectomy in 5 patients. The mortality rate was 0. Pathological findings were insulinoma or neuroendocrine tumors in 26 of 27 cases. One patient had a pathological finding of chronic pancreatic disease with intraepithelial neoplasia (grade 1A). CONCLUSION: We conclude that the preoperative localization of insulinoma in clinically suspected patients can be made on the basis of MRI and/or CT studies. A hallmark lesion is hypointense in T(1)-weighted sequences, homogeneously or peripherally hyperintense in T(1)-weighted fat-suppressed contrast-enhanced sequence using MRI (100% of cases) or/and a hypervascular enhanced lesion on arterial (100% of CT studies) and on venous series using CT (66.7% of CT studies).
    Type of Publication: Journal article published
    PubMed ID: 22042212
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    ISSN: 0168-583X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 1464-1467 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A novel silicon surface barrier detector has been constructed for low-energy electron spectroscopy. This detector consists of a high-resistance silicon wafer which is sandwiched between a rectifying barrier front and ohmic back contacts. The front electrode is a gold mesh metallization with an effective area of 8% of the detector surface. This electrode allows most of the electrons to reach the active region of the detector with the smallest possible degradation in their energy distribution due to electron straggling in the front electrode.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 2205-2210 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the second harmonic generation (SHG) using a 1.06 μm Q-switched pump beam in powdered nonlinear crystals suspended in a photopolymeric solution. The powdered crystals used include lithium niobate, LiNbO3, and potassium titanyl phosphate. Measurements were made as a function of the grain size and the number of grains per unit volume. The photopolymeric solution is transparent at the pump beam frequency while it is highly absorbing at the SH and it is the SH which transforms the photopolymer from liquid to solid. The results show that relatively intense SH incoherent light is produced in powder after the pump intensity exceeds a certain threshold. SHG does not depend on the grain size up to a critical grain size beyond which SHG falls off rapidly. Furthermore, the emission increases linearly as a function of the number of grains per unit volume and eventually levels off and stays constant. A practical focus of these studies has been in the areas of laser induced rapid prototyping and three dimensional real time image formation. This study clearly demonstrates the application of a nonlinear optical medium in high resolution rapid prototyping. Furthermore, because efficient SHG occurs for very small powder grain size this technique may provide a way of realizing high resolution three dimensional imaging in which the feature size is only a few microns. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 3343-3345 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A high-current, nanosecond-pulse generator is described, ideal for driving low-impedance loads such as laser diodes. The generator utilizes step recovery diodes in a unique biasing scheme to produce 0.1–5 A pulses with pulse widths varying from 2 to 10 ns.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electrical transport properties of CoSi2 and Co(SixGe1−x)2 thin films formed by solid state interaction and co-evaporation in the range of 4–300 K were studied. The Hall effect data indicate a hole carrier conduction in all samples. The rapid thermal annealed CoSi2 exhibits a typical metallic conduction with a residual resistivity of 3.3-μΩ-cm and room-temperature (RT) resistivity of 15 μΩ cm. The co-evaporated CoSi2 and Co(Si0.9Ge0.1)2 films after low temperature annealing up to 250 °C show a low resistivity of 70–80 μΩ cm at RT and change little down to 4 K. The hole carrier density of all the samples studied has values close to 2–3×1022 cm−3, while the carrier Hall mobility has large differences.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 756-758 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ion-exchange processes in potassium titanyl phosphate (KTiOPO4 or KTP) single crystal immersed in Rb, Rb–Ba, Rb–Sr nitrate molten solutions have been investigated by using Rutherford backscattering depth-profile analysis. The depth to which Rb-ion exchange occurred in KTP was found to be sensitive to the presence of as little as 0.1% of a Ba impurity in a molten solution of rubidium nitrate. The addition of impurities such as Ba significantly increased the ion-exchange depth of Rb in KTP, and the Rb distribution after ion exchange. Using pure RbNO3, however, the depth of the Rb ion exchange was relatively shallow, and the Rb surface concentration was measurably greater at the minus than at the plus polar-axis faces of the crystal. These findings are relevant to the application of ion-exchange techniques to the fabrication of optical waveguides on KTP substrates. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 4096-4098 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low-field ac susceptibility measurements have been performed on disordered Ni1−x Mnx, where x=0.216, 0.225, and 0.265, under hydrostatic pressure up to 21 kbar. The measured susceptibility χm exhibits transitions from paramagnetic to quasiferromagnetic to spin-glass states on cooling. The pressure dependence indicates a decrease in the magnitude of χm and opposite shifts in the temperatures of the two transitions. The nature of the quasiferromagnetic state is discussed.
    Type of Medium: Electronic Resource
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