Browsing by Author "Heuser, Markus"

Aim: In this retrospective study, we assess the current role and future potential of computed tomography (CT) in the diagnostic algorithm of acute pulmonary embolism (PE). Materials and methods: Two hundred patients underwent 64-multidetector-row spiral CT of the chest, pelvis, and thigh for suspected PE. CT scans were reviewed, and the degree of contrast enhancement and the presence of PE and/or (deep) venous thrombosis were recorded. In the case of PE, the level of thrombus was noted as central, main, or lobar. If the scan yielded a positive result for thrombosis, intravenous localization was also determined. Patient age, length of admission, clinical course, clinical indication, and incidental findings were registered as well. Results: PE was detected in 60 of the 200 patients with a high clinical probability of having PE (30%). Thirty-four patients had a positive CT scan result for venous thrombosis (17%). Twenty-four of the 60 patients had proximal deep venous thrombosis (40%), and 2 patients had ann venous thrombosis (3%). Thirty-four of the 60 patients had without venous thrombosis (57%). Eight of the 200 patients had deep venous thrombosis without suspicion of PE (4%). The distribution of the proximal thrombi showed 15 in a central artery (25%), 13 in a main pulmonary artery (22%), and 32 in a lobar segmental artery (53%). There was diffuse allocation of the thrombus in all lobes. Furthermore, CT scan noted a total of 120 incidental findings. Conclusion: Our study indicates the potential clinical use of a diagnostic strategy for ruling out PE based on D-dimer testing and multidetector-row CT. A larger outcome study is needed before this approach can be adopted. (C) 2008 Elsevier Inc. All rights reserved.

Integrin-mediated cell adhesion and signaling is essential to vascular development and inflammatory processes. Elevated expression of integrin alpha(v)beta(3) has been detected in ischemia-reperfusion injury and rejecting heart allografts. We thus hypothesized that the inhibition of alpha(v)-associated integrins may have potent anti-inflammatory effects in acute kidney allograft rejection. We studied the effects of a peptidomimetic antagonist of alpha(v) integrins in two rat models of renal allotransplantation, differing in degree of major histocompatibility complex mismatch. Integrin alpha(v)beta(3) was up-regulated in rejecting renal allografts. Integrin antagonist reduced the histological signs of acute rejection, the intensity of the mononuclear cell infiltration, and cell proliferation in the grafted kidneys. This could be correlated to a reduced leukocyte-endothelial interaction and an improved peritubular microcirculation observed by intravital microscopy. In vitro under laminar flow conditions, the arrest of monocytes to interleukin-1 beta-activated endothelium was decreased. Furthermore, in co-culture models the proliferation and transmigration of monocytes/macrophages, endothelium, and fibroblasts induced by renal tubular epithelia was efficiently inhibited by alpha(v) integrin antagonism. These data reveal an important role of this integrin subclass in leukocyte recruitment and development and maintenance of acute rejection; blockade of alpha(v) integrins may provide a new therapeutic strategy to attenuate acute allograft rejection.

Aim: In this retrospective study, we assess the current role and future potential of computed tomographic (CT) colonography as a viable alternative imaging tool for colorectal polyp detection and colon cancer screening. Materials and methods: Twenty patients have undergone virtual colonographic examinations with 64-multidetector-row spiral CT (MDCT), and three-dimensional images were created on a separate workstation that had the appropriate software for image processing. Images were reviewed by a radiologist, and anatomic division of the entire colon was used to locate the suspected lesions. Characteristics of bowel preparation, intracolonic, extracolonic, and incidental findings were noted, too. Results: Ten of the 20 patients (50%) had a positive CT colonography for polypoid lesions. Those lesions were distributed into the cecum (4 cases), colon ascendens (2 cases), colon descendens (2 cases), and sigma (2 cases). In 80%, bowel preparation was good, in 15% moderate, and in 5% inadequate. Furthermore, CT scan noted in total 20 incidental findings. Conclusion: CT colonography is currently a viable alternative imaging tool for colorectal polyp detection. There are several clinical situations where CT colonography may play an important role in patient care. These include for example evaluation of the colon after an incomplete conventional colonoscopic examination or evaluation in patients who are clinically unfit to undergo conventional colonoscopy. At centers where there is expertise in data acquisition and interpretation, CT colonography is being offered as a routine imaging examination. With continued improvements in bowel preparation, colonic distention, and CT colonography interpretation by sufficient numbers of radiologists this technology might have a substantial influence on colon cancer screening. (c) 2008 Elsevier Inc. All rights reserved.

Nowadays, computed tomography (CT) is established for diagnosing gastrointestinal bleeding. In this retrospective study, the use of CT in diagnosing gastrointestinal bleeding was evaluated. Fifty-three patients received a contrast-medium-enhanced helical multislice CT (MSCT) to locate the bleeding site. Seventy-nine percent of the hemorrhage were acute gastrointestinal bleedings. Fifty-five percent of the acute hemorrhages were located via helical MSCT, 45% of the chronic bleeding sites were detected. Notably, bleeding of diverticula, tumors, and angiodysplasias were well demonstrated. In conclusion, contrast-medium-enhanced MSCT may be used effectively as a noninvasive diagnostic tool for detecting gastrointestinal bleedings. (C) 2008 Elsevier Inc. All rights reserved.

Objectives: Evaluation of a silicon-based flat panel volumetric computed tomography (fpVCT) and multislice CT in terms of volumetry of phantoms with different algorithms. Furthermore, to compare the different volumetric analysis methods themselves. Materials and Methods: Four phantoms of different materials have been scanned with fpVCT (GE prototype with circular gantry with 2 aSi/CsI flat panel detector) and a 64-slice spiral CT (MSCT: LightSpeed VCT). Three spherical phantoms of different materials and 1 phantom with an irregular shape were evaluated. True volumes were calculated in dependence from the diameter or by water displacement method. Imaging parameters (80 kVp, 100 mA) and the position of the phantoms were identical in both techniques. After reconstruction of the images different algorithms have been used 4 times for each phantom. These analysis methods have been performed: Region growing, threshold method, planimetry, 3-dimensional volumetry measurement by using the equation of an ellipsoid (ellipse) and an advanced lung analysis modus [single advanced lung analysis (ALA)]. The mean values and the standard deviations have been evaluated and compared with the true volumes. Results: In all phantoms fpVCT showed better results with lower deviations from the true values than in MSCT, especially for small volumes of the phantoms. However, the results of the ALA single method demonstrated no significant difference between the fpVCT and MSCT. The comparison of the different analysis methods revealed that 3-dimensional measurement with the ellipse method was the worst method for volume estimation, especially for the irregularly formed phantom. Conclusion: fpVCT was superior to MSCT in the volumetry of small objects. The ellipse method has been shown to be the worst for volumetry with the highest relative deviations from the true volume value. The single ALA method shows the lowest standard deviation thereby revealing a reproducible volumetric method for small nodules. However, further future developments of volumetric analysis methods are necessary to use them accurately in daily routine. Due to the truly isotropic volume data set with high spatial resolution fpVCT is a powerful tool for the volumetry of small nodules.

Objectives: The aim of this study was to compare the image performance of silicon-based flat-panel-detector-based volumetric computed tomography (fpVCT) to multislice spiral computed tomography (MSCT) for the visualization and detail delectability of skeletal structures in rodents of different development stages. Materials and Methods: Rodents of different development stages were imaged with fpVCT (GE prototype with circular gantry with two 1024 x 1024, 200-mu m pixel size, amorphous silicon/Cesium lodid (Csl) flat-panel detector) and eightslice MSCT (LightSpeed Ultra). Imaging parameters (80 kVp, 100 mA) and the position of the rodents were identical in both techniques. Image quality, detail delectability, and contour of skeletal structures were judged by two observers in consensus using a 4-point scale (1=unsatisfactory... 4=good). Findings were displayed and evaluated in axial slices, multiplanar reconstructions (MPR), maximum intensity projections (MIP) and volume rendering technique (VRT) in both modalities. Mean and standard of error of mean were calculated. Results: In axial slices, visualization and detail delectability of very subtle skeletal structures, e.g., the basis of the skull was better in fpVCT than in MSCT (4 vs. 2 points). The MPRs of fpVCT showed less artifacts and more details than those of the MSCT. The MIPs and VRTs of the fpVCT demonstrated best image quality in all rodents of different development stages, whereas MSCT showed significant artifacts. Conclusion: fpVCT outperformed MSCT in imaging of small rodents. Due to the truly isotropic volume data set with high spatial resolution, fpVCT is a powerful tool in evaluating detailed skeletal structures. (c) 2007 Elsevier Inc. All rights reserved.

The function of the androgen-regulated homeobox protein NKX3.1 in prostate cancer is controversial. NKX3.1 is necessary for correct prostate development and undergoes frequent allelic loss in prostate cancer. However, no mutations occur in the coding region and some particularly aggressive cancers over-express the protein. Nevertheless NKX3.1 is often referred to as candidate tumor suppressor gene. Recent findings suggest a function in protection against oxidative damage involved in prostate carcinogenesis. Thus NKX3.1 may act differently at various stages of prostate cancer. Unlike a classical tumor suppressor NKX3.1 is up-regulated by androgens and down-regulated by phytoestrogens. In this study we performed RNAi based functional analysis by knocking down NKX3.1 expression in LNCaP prostate cancer cells and analyzing the impact of NKX3.1 on gene expression and cell proliferation. Knockdown of NKX3.1 evoked a massive down-regulation of NKX3.1 expression, followed by reduction in mRNA expression of the androdrogen receptor (AR) and the insulinlike growth factor receptor (IGF-1R). Western blot analysis showed strong decreases of NKX3.1, AR, and IGF-1R protein expression. Concomitantly, cell proliferation decreased and expression of prostate-specific antigen (PSA) mRNA and its secretion were diminished, whereas expression of IGF binding protein 3 (IGFBP-3) and MMP tissue inhibitor 3 (TIMP-3) was up-regulated. In tumor cells not deprived of NKX3.1 expression this gene still has a function which might differ from its role in prostate development and carcinogenesis. NKX3.1 knock-down altered the expression of genes highly relevant in prostate cancer cell proliferation and apoptosis. In LNCaP NKX3.1 most probably plays the role of an androgenregulated transcription factor whose down-regulation is paralleled by anti-proliferative and pro-apoptotic effects. Since NKX3.1 can regulate AR expression it may become a target for interference in hormone refractory prostate carcinoma.

The kidney, bladder and male urethra are the organs typically injured by blunt and penetrating trauma to the urinary tract, whereas the ureter is only rarely injured. The staging of genitourinary tract trauma has recently gained tremendous significance due to improvements in ultrasound, CT and MRI, including contrast-enhanced magnetic resonance angiography, and has become a helpful tool for decision making with regard to conservative and surgical management. Furthermore, interventional radiology may be helpful to control hemorrhage from vessels in the pelvic region that may not be easily accessed by open surgery. Therefore, this pictorial essay gives examples of the radiological presentation of genitourinary trauma and describes technical details of the diagnostic imaging modalities used.

Renal cell carcinomas (RCC) frequently express the gastrin-releasing peptide receptor (GRP-R). Gastrin-releasing peptide (GRP) stimulates tumor cell proliferation and neoangiogenesis. Tumor-associated macrophages (TAM) comprise an important cellular component of these tumors. We analyzed the GRP/GRP-R network in clear cell RCC (ccRCC) and non-clear cell RCC (non-ccRCC) with special regard to its expression by macrophages, tumor cells and microvessels. Gastrin-releasing peptide and GRP-R expression in 17 ccRCC and 9 non-ccRCC were analyzed by RT-PCR, immunohistochemistry and double immunofluorescence staining. Tumor-associated macrophages expressed GRP and GRP receptor in ccRCC. Tumor cells and microvessels showed low to intermediate GRP-R expression in nearly all cases. In 12 ccRCC tumor epithelia also expressed low levels of GRP. Microvascular GRP expression was found in nine cases of ccRCC. For non-RCC, the expression of GRP and GRP receptor expression pattern was similar. Tumor-associated macrophages are the main source of GRP in RCC. GRP receptor on TAM, tumor epithelia and microvessels might be a molecular base of a GRP/GRP receptor network, potentially acting as a paracrine/autocrine modulator of TAM recruitment, tumor growth and neoangiogenesis.