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  • 1
    Keywords: THERAPIES ; RADIATION-THERAPY ; THERAPY ; radiotherapy ; radiation ; INFORMATION
    Type of Publication: Book chapter
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  • 2
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    German Medical Science GMS Publishing House; Düsseldorf
    In:  Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2015); 20151020-20151023; Berlin; DOCPO12-1335 /20151005/
    Publication Date: 2015-10-06
    Keywords: Pseudarthrose ; Masquelet Technik ; Zytokine ; TGF-ß1 ; PDGF-AB ; IGF-1 ; Knochenregeneration ; ddc: 610
    Language: German
    Type: conferenceObject
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  • 3
    Abstract: Recent experimental and clinical studies have provided compelling evidence that diabetes mellitus (DM) is an important risk factor in various cancers, and may affect both pathogenesis and prognosis. Additionally, antidiabetic agents such as metformin exhibit an antitumorigenic effect. However, to date there is insufficient knowledge about the role of DM in the pathogenesis and prognosis of head and neck squamous cell carcinoma (HNSCC).In a retrospective monocentric study including 424 patients with SCC of the oropharynx (OPSCC) or larynx (LaSCC), the impact of DM on clinical and histopathologic parameters was investigated. The authors found a rising incidence of DM among LaSCC patients (〈10 % until 2005 and 20 % since 2006) and a significant association between DM and clinical and histopathologic features (age, gender, tumor size, and pathologic grading), which depended on the anatomic site. Moreover, a clear trend toward unfavorable progression-free and overall survival of HNSCC patients with DM upon current treatment modalities was evident.The presented data support a relative increase in patients with DM, particularly for LaSCC. This might have a sustained influence on treatment decisions and management, and should be considered in future clinical trials. A better understanding of the cellular and molecular traits of HNSCC in DM could pave the way for innovative therapeutic strategies in terms of personalized medicine.
    Type of Publication: Journal article published
    PubMed ID: 27307061
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  • 4
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    German Medical Science GMS Publishing House; Düsseldorf
    In:  85. Jahresversammlung der Deutschen Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie; 20140528-20140601; Dortmund; DOC14hnod300 /20140414/
    Publication Date: 2014-04-15
    Keywords: ddc: 610
    Language: German
    Type: conferenceObject
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  • 5
    Keywords: brain ; measurement ; evaluation ; Germany ; MODEL ; ALGORITHM ; IMAGES ; INFORMATION ; QUANTIFICATION ; SYSTEM ; ACCURACY ; RESOLUTION ; PATIENT ; animals ; CONTRAST ; PERFORMANCE ; DISTRIBUTIONS ; AMPLIFICATION ; LINE ; positron emission tomography ; POSITRON-EMISSION-TOMOGRAPHY ; tomography ; Jun ; DEGRADATION ; PET ; ARTIFACTS ; RECONSTRUCTION ; 2D ; DISORDERS ; VARIANT ; HIGH-RESOLUTION ; 3D-data-acquisition ; CAMERA ; image reconstruction ; IMAGE-RECONSTRUCTION ; OSEM algorithm ; PERFORMANCE EVALUATION ; RESTORATION ; SMALL ANIMALS ; SPECT LIVER TOMOGRAMS ; WHOLE-BODY
    Abstract: Aim: Improvement of the spatial resolution in positron emission tomography (PET) by incorporation of the image-forming characteristics of the scanner into the process of iterative image reconstruction. Methods: All measurements were performed at the whole-body PET system ECAT EXACT HR+ in 3D mode. The acquired 3D sinograms were sorted into 2D sinograms by means of the Fourier rebinning (FORE) algorithm, which allows the usage of 2D algorithms for image reconstruction. The scanner characteristics were described by a spatially variant line-spread function (LSF), which was determined from activated copper 64 line sources. This information was used to model the physical degradation processes in PET measurements during the course of 2D image reconstruction with the iterative OSEM algorithm. To assess the performance of the high-resolution OSEM algorithm, phantom measurements performed at a cylinder phantom, the hotspot Jaszczack phantom, and the 3D Hoffmann brain phantom as well as different patient examinations were analyzed. Results: Scanner characteristics could be described by a Gaussian-shaped LSF with a full-width at half-maximum increasing from 4.8 mm at the center to 5.5 mm at a radial distance of 10.5 cm. Incorporation of the LSF into the iteration formula resulted in a markedly improved resolution of 3.0 and 3.5 mm, respectively. The evaluation of phantom and patient studies showed that the high-resolution OSEM algorithm not only lead to a better contrast resolution in the reconstructed activity distributions but also to an improved accuracy in the quantification of activity concentrations in small structures without leading to an amplification of image noise or even the occurrence of image artifacts. Conclusion: The spatial and contrast resolution of PET scans can markedly be improved by the presented image restauration algorithm, which is of special interest for the examination of both patients with brain disorders and small animals
    Type of Publication: Journal article published
    PubMed ID: 15201947
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  • 6
    Keywords: PEPTIDE ; RECEPTOR ; CANCER ; IN-VITRO ; tumor ; carcinoma ; Germany ; IN-VIVO ; LUNG ; VITRO ; DENSITY ; imaging ; lung cancer ; LUNG-CANCER ; TISSUE ; TUMORS ; MICE ; TIME ; PATIENT ; RAT ; CONTRAST ; BINDING ; BREAST ; BREAST-CANCER ; ACID ; ASSAY ; NUDE-MICE ; LINE ; LOCALIZATION ; BIODISTRIBUTION ; STRATEGIES ; PET ; nuclear medicine ; TRACER ; targeting ; MOLECULAR-BASIS ; RE ; SOMATOSTATIN ANALOG ; PROSTATE-CANCER CELLS ; ASSAYS ; INTERNALIZATION ; RADIOLIGAND ; Ga-68 ; bombesin analog ; EXPRESSING TUMORS ; gastrin-releasing peptide receptor imaging ; PEPTIDE RECEPTORS ; RADIOCHEMICAL INVESTIGATIONS ; VITRO/IN VIVO
    Abstract: Bombesin (BN), a 14-amino-acid peptide, shows high affinity for the human gastrin-releasing peptide receptor (GRP-r), which is overexpressed on several types of cancer, including prostate, breast, gastrointestinal, and small cell lung cancer. Thus, radiolabeled BN or BN analogs may prove to be specific tracers for diagnostic and therapeutic targeting of GRP-r-positive tumors in nuclear medicine. This study evaluated a novel BN analog labeled with the positron emitter Ga-68 for receptor imaging with PET. Methods: DOTA-PEG(2)-[D-Tyr(6), beta-Ala(11),Thi(13), Nle(14)] BN(6-14) amide (BZH3) (DOTA is 1,4,7,10-tetraazacyclododecane-N,N',N",N'"-tetraacetic acid; PEG is ethyleneglycol (2-aminoethyl)carboxymethyl ether) was synthetized using the Fmoc strategy and radiolabeled with either Ga-67 or Lu-177 for in vitro and biodistribution experiments. Ga-68 for PET was obtained from a Ge-68/Ga-68 generator. In vitro binding, internalization, and efflux were determined using the pancreatic tumor cell line AR42J. Biodistribution of the peptide as a function of time and dose was studied in AR42J tumor-bearing mice. Results: In vitro assays demonstrated a high affinity of Ga-67-BZH3 (dissociation constant = 0.46 nmol/L), a rapid internalization (70% of total cell-associated activity was endocytosed after a 15-min incubation), and an intracellular retention half-life (t(1/2)) of the 67Ga activity of 16.5 +/- 2.4 h. Biodistribution indicated a dose-dependent uptake in the tumor and a prolonged tumor residence time (t(1/2) similar to 16 h). Clearance from GRP-r-negative tissues was fast, resulting in high tumor-to-tissue ratios as early as 1 h after injection. Replacing Ga-67 by Lu-177, a therapeutic radionuclide, for peptide labeling resulted in a slightly reduced (similar to 20%) tumor uptake and tumor residence time of Lu-177-BZH3. In contrast, Lu-177 decline in the pancreas was significantly accelerated by a factor of similar to 3 compared with that of Ga-67. PET of mice with Ga-68-BZH3 clearly delineated tumors in the mediastinal area. Conclusion: The promising in vivo data of Ga-68-BZH3 indicate its potential for an improved localization of GRP-r-positive tumors and also suggest its application in patients. PET may also be favorably used for GRP-r density determination, a prerequisite for therapeutic applications
    Type of Publication: Journal article published
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  • 7
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  • 8
    Keywords: RECEPTOR ; ANGIOGENESIS ; EXPRESSION ; radiotherapy ; tumor ; Germany ; MODEL ; CT ; imaging ; SYSTEM ; VOLUME ; RISK ; meningioma ; TISSUE ; TUMORS ; PATIENT ; CONTRAST ; MRI ; BINDING ; AGE ; PARAMETERS ; PET ; KINETICS ; RECEPTORS ; ORGANIZATION ; monitoring ; PERFORMANCE EVALUATION ; SOMATOSTATIN RECEPTORS ; SUBTYPE ; neuroendocrine tumor ; SUBTYPES ; MENINGIOMAS ; HIGH EXPRESSION ; Ga-68-DOTA-TOC ; GA-68-DOTATOC ; kinetic modeling ; SOMATOSTATIN RECEPTOR SCINTIGRAPHY
    Abstract: Because biopsy has a high risk of hemorrhage and the findings of CT and MRI are often ambiguous, especially at the base of the skull, additional methods for the characterization of intracranial tumors are needed. Meningiomas show high expression of the somatostatin receptor subtype 2 and thus offer the possibility of receptor-targeted imaging. We used the somatostatin analog Ga-68-DOTA-D-Phe(1)-Tyr(3)-octreotide (DOTA-TOC) labeled with the positron emitter Ga-68 (half-life, 68 min), obtained from a Ge-68/Ga-68 generator, for PET of these tumors. In contrast to F-18-FDG, this ligand shows high meningioma-to-background ratios. The aim was to evaluate kinetic parameters in meningiomas before radiotherapy. Methods: Dynamic PET scans (3-dimensional mode; 28 frames; ordered-subsets expectation maximization reconstruction) were acquired for 21 patients (mean age ± SD, 51 ± 13 y) before radiotherapy during the 60 min after intravenous injection of 156 ± 29 MBq of Ga-68-DOTA-TOC. We analyzed 28 meningiomas (median grade [1] according to the system of the World Health Organization) with volumes of at least 0.5 mL (mean volume, 13.1 mL) and nasal mucosa as reference tissue, showing a slight to moderate physiologic uptake. For evaluation of the 68Ga-DOTA-TOC kinetics, the vascular fraction (vB) and the rate constants (k1, k2, k3, and k4 [1/min]) were computed using a 2-tissue-compartment model. Furthermore, receptor binding (RB) (k1 - k1 X k2) and the ratios k1/k2 and k3/k4 were calculated. Results: Significant differences (P < 0.05; t test) between meningiomas and the reference tissue were found for the mean standardized uptake value (10.5 vs. 1.3), vB (0.42 vs. 0.11), k2 (0.12 vs. 0.56), k3 (0.024 vs. 0.060), k4 (0.004 vs. 0.080), and RB (0.49 vs. 0.13). Although there was no significant difference for k1 (0.54 vs. 0.40), the ratios k1/k2 (4.50 vs. 0.71) and k3/k4 (6.00 vs. 0.75) were markedly greater in meningiomas than in reference tissue. Conclusion: The high uptake of Ga-68-DOTA-TOC in meningiomas can be explained by the high values for vB and by the remarkably low values for k2 and k4, leading to significantly greater k1/k2 and k3/k4 ratios and RB in meningiomas than in reference tissue. Thus, pharmacokinetic modeling offers a more detailed analysis of biologic properties of meningiomas. In further studies, these data might serve as a basis for monitoring the somatostatin receptors of meningiomas after radiotherapy
    Type of Publication: Journal article published
    PubMed ID: 15872348
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  • 9
    Keywords: Germany ; IN-VIVO ; VIVO ; imaging ; SYSTEM ; animals ; SUPPRESSION ; PROBES ; SELECTION ; sensitivity ; FLUORESCENCE ; CROSS-TALK ; RE ; EXTENSION ; ARRAY ; REPORTER GENE ; development ; NUCLEAR ; optical imaging ; USA ; UNIT ; in vivo ; animal ; phantom ; EMISSION-TOMOGRAPHY ; PHOTON ; DETECTORS ; small animal imaging ; SETUP ; scanning ; EMISSION ; emission tomography ; positron ; BIOLUMINESCENCE ; dual-modality imaging ; IMAGING-SYSTEM
    Abstract: Herein, we present a novel concept for fully integrated dual-modality in vivo tomographic imaging yielding simultaneous detection of positron and optically labeled probes in small animals. The imager consists of an allocation of optical detector modules and, in radial extension, the allocation of positron emission detector modules. Laser scanning and large-field light sources are integrated to facilitate fluorescence imaging in addition to bioluminescence imaging. Each optical detector unit consists of a large-area photon sensor for light detection, a microlens array for field-of-view definition, a septum mask for cross-talk suppression, and a transferable filter for wavelength selection. To prove the working principle of the dual-modality detector system a pair of optical detectors along with a large-field excitation source was placed inside the bore of a Siemens EXACT HR+ scanner, performing simultaneous imaging. The imaging characteristics of the optical detector were evaluated experimentally using a prototypical setup with geometrical phantoms. The sensitivity of the optical detector prototype was found less than that of a reference CCD camera. We propose several ways of increasing optical detector sensitivity
    Type of Publication: Journal article published
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  • 10
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 3871-3875 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A new numerical procedure for the study of finite temperature quantum dynamics is developed. The method is based on the observation that the real and imaginary time dynamical data contain complementary types of information. Maximum entropy methods, based on a combination of real and imaginary time input data, are used to calculate the spectral densities associated with real time correlation functions. Model studies demonstrate that the inclusion of even modest amounts of short-time real time data significantly improves the quality of the resulting spectral densities over that achievable using either real time data or imaginary time data separately. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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