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The effectiveness of dental implants is largely dependent upon the biostability and osteointegration of the bone-implant interface. Examination of HA-coated subperiosteal dental explants may provide insight into the quality of the bone-coating attachment. The goals of the present study were to characterize osteointegration near the interface of three retrieved devices using nanoindentation and study the variability in hardness and elastic modulus as a function of distance from the bone-implant interface. The nanoindentation tests resulted in different trends for each patient. No consistent differences were seen comparing the modulus and hardness of bone near the interface ( 100 μm). As a result, we could not conclude how the HA coatings affected bone quality around the subperiosteal implants. Ongoing efforts are directed at improving specimen preparation technique to reduce errors due to surface roughness and lamellar orientation. Histomorphometric analysis will be done in order to study the differences in bone quantities among patients.

Cancer of unknown primary (CUP) is defined as malignancy without known origin at the time of the initial diagnosis, thus representing a heterogeneous group of tumors with varying clinical features. Between 0.5% and 7% of all cancer patients are diagnosed with cancer of an unknown primary tumor (van de Wous et al. 2002). Detected primary revealed lung cancer most often, followed by oropharynx carcinoma, nasopharynx, breast, colorectal, and esophagus carcinoma (Delgado-Bolton et al. 2003). Overall the primary tumor in CUP patients is detected in less than 40% of the patients by conventional diagnostic procedures, frequently after having performed many examinations in all patients. Moreover, even with autopsy the primary could only be detected in approximately 80%. Hypothesized reasons are a metastatic phenotype with a small size of the primary due to involution during the course of disease or an extremely slow growth rate, but none of the biological hypotheses is confirmed by results from the literature (Van de Wouw et al. 2003).

The increasing miniaturization in non-volatile data-storage devices offers the opportunity of a substantial shortening of read-write cycles. In order to study the underlying physical phenomena and fundamental limits it is necessary to probe the spin-dynamics in nanostructures on a fsec time-scale. We present an approach where this can be achieved together with the required nm spatial resolution. The method is based on the combination of fsec pump-probe laser-techniques and photoelectron emission microscopy. Magnetic sensitivity is obtained by analyzing the spin-polarization of the emitted photoelectrons. We will present an application of the technique to CoPt nanoscale magnetic dots.

Due to the high spatial resolution and the excellent capability of imaging of osseous structures, computed tomography (CT) is of great importance for the diagnosis of pathologic changes of the skull base. CT is the method of choice for the diagnostic evaluation of fractures and middle ear diseases, such as middle ear hearing loss and anomalies [3]. Examination in transverse and coronal plane is necessary for the detection of discrete lesions.

The usual way to document medical data is using 2D images and textual transcription as medium. But for analysing the position and the spatial dimensions of an aneurysma 3D information is mandatory. This information can be provided by digital videos that show the visualized 3D medical data set. However, to generate such videos usually is a very inconvenient and time-consuming procedure. To automate this it is necessary to define a standardized way of observing the medical data set. The following paper presents an approach to automatically record a digital video sequence of an aneurysma in CT-data sets which is based on hardware supported texture mapping.

In einer Phase ll-Studie wurde die Effektivitat einer multimodalen Therapie in prognostisch ungunstigen Stadien des Bronchialkarzinoms untersucht. 94 Patienten mit nichtkleinzelligem Bronchialkarzinom (NSCLC) im Stadium IIIA u. IIIB erhielten eine praoperative Chemo/Radiotherapie (Cisplatin u. Etoposid, hyperfraktionierte akzelerierte Bestrahlung). Nach Remediastinoskopie wurden geeignete Patienten operiert. Eine R0-Resektion erreichten 53% aller Patienten. Praoperativ verstarben zwei Patienten therapieabhangig an einer Sepsis. 4 Patienten verstarben postoperativ (90-Tage-Letalitat 6,4%). Das mediane Uberleben betrug 20 Monate fur IIIA-Patienten und 18 Monate fur IIIB-Patienten. Das aktuarielle 6-Jahres-Uberleben betrug 34% (IIIA) und 17% (IIIB). Somit ist die multimodale Behandlung im Vergleich mit historischen Zahlen beim lokal weit fortgeschrittenen Bronchialkarzinom sehr effektiv.

Degenerative diseases of the vertebral column are mainly combined with misalignments of the intervertebral discs and deformations of the spinal cord. For the investigation of severe spinal stenosis and herniated intervertebral discs x-ray myelography is required providing important functional information about the motion of vertebral segments. To avoid this time-consuming procedure and the injection of contrast agent, we introduce a non-invasive approach using direct volume rendering of a novel T2 weighted MR sequence. It provides meaningful representations of extreme spinal pathologies. Above all, the essential functional information is obtained using an adjustable couch directly applied within the MR scanner. Due to the distribution of the grey values, we suggest a coarse segmentation of the vertebral column using a fast sequence of filtering operations and volume growing. Further on, details are delineated implicitly using interactive adjustment of transfer functions. Thereby, the CSF, the roots of the spinal nerves and the vertebrae are clearly visible. Additionally, we propose an approach for volumetric measurement providing the functional dependence of the CSF volume. The presented non-invasive strategy gives a comprehensive understanding of spatial and functional information including spinal instability and may thus lead to further reduce the need of x-ray myelography.

A high quality polygonal model of the temporal bone and the structures related to the middle and inner ear is presented. The segmentation of the spiral CT-data and the reconstruction was performed in an iterative process taking several hours to complete. In comparison to this, the power of direct volume rendering is presented which produces meaningful images of the same data in a very short time by interactively adjusting pre-defined color look-up tables. Additionally, using hardware assisted registration, the fusion of CT- and MR-data gives an even more comprehensive representation of the whole situation. Examples demonstrate the direct clinical application and show the value for the planning of neurosurgery.

Dural arteriovenous fistulae are the cause of various somatic diseases. For their analysis DSA is used in medical practice. However, the injection of contrast dye into the vertebral segmental arteries is a time-consuming and highly difficult procedure. Aiming at a reduction of the number of injections required for the detection and exact localization of the pathology, we introduce a new approach which provides meaningful visualization of MR-CISS volumes. Due to the limited spatial resolution of the image data an explicit segmentation of the small vascular structures is extremely difficult. Therefore, we propose a fast sequence of filtering operations and volume growing in order to separate the areas of background, spinal cord and cerebrospinal fluid. Consecutively, we suggest implicit segmentation within these sub-volumes. This is achieved by interactively adjusting transfer functions of pre-defined color lookup tables with a few manipulation operations. Thereby, the tiny target vessels contained within the area of cerebrospinal fluid are clearly delineated. Overall, the presented non-invasive approach ensures an optimal spatial understanding of vessel structures in relation to the surrounding anatomy and contributes significantly to reduce the number of injections during DSA examinations.

The diagnosis of intracranial aneurysms and the planning of related interventions is effectively assisted by spiral CT-angiography and interactive direct volume rendering. Based on 3D texture mapping, we suggest a hardware accelerated approach which provides fast and meaningful visualization without time-consuming pre-processing. Interactive tools provide reliable measurement of distance and volume allowing to calculate the size of vessels and aneurysms directly within the 3D viewer. Thereby, the expensive material required for coiling procedures is estimated more precisely. Interactively calculated shaded isosurfaces, presented in [1] were evaluated in respect of enhanced perception of depth. Based on the integration into OpenInventor, global overview and simultaneous detail information is provided by communicating windows allowing for intuitive and user-guided navigation. Due to an average of 15–20 minutes required for the complete medical analysis, our approach is expected to be useful for clinical routine. Additional registration and simultaneous visualization of MR and CT-angiography gives further anatomical orientation. Several examples demonstrate the potential of our approach.

The aim of the study was to evaluate 3D computed tomography (3D-CT) for the visualization of tumor extent with respect to the infiltration of the pulmonary arteries in patients with locally advanced small and nonsmall-cell lung cancer. A total 61 examinations in 40 patients with bronchial carcinoma were performed with contrast-enhanced (150 ml injected with 4 ml/s after bolus tracking) 2 mm spiral CT (pitch 1.5, increment 1 mm) (Somatom Plus4, Siemens AG, Germany). Using the implemented Software eine mode, surface shaded display (SSD), and maximum intensity projection (MIP), reconstruetions of the pulmonary arteries and the tumors were generated. In comparison to conventional spiral thoracic CT, the optimized cross-sectional images of the mediastium represented a benefit with the technique described, and this can help to diagnose vessel infiltration and may therefore be of value for pre- and post-therapeutic Staging in modern stage-adapted multimodality treatment programs.

We studied 30 patients with retrobulbar lesions preoperatively with a 1.0 T whole-body MR system. The examinations were evaluated according to histological grading, grade of malignancy and delineation from neighbouring anatomical structures. Axial T1-weighted spinecho sequences before and after contrast medium and a T2-weighted double-echo spin-echo sequence were obtained using a circular polarised head coil. MRI, especially with fat-suppressing techniques, is superior to ultrasound and CT as regards delineation, and comparable to CT as regards the grade of malignancy.

Over the past decade studies of the decay processes following both core-electron excitation as well as core-electron ionization have been carried out for a variety of small molecules in gas phase and in a physisorbed or chemisorbed state. This was made possible through the application of synchrotron radiation used in preparing well-defined highly-excited states. These investigations of the electronic decay of specifically-prepared electronic configurations offer unique ways to study electron correlation and dynamic charge transfer and screening processes in well characterized electronic systems. Moreover, high-resolution studies taken with a resolving power sufficient to resolve vibrational substates in both the excitation and decay channels, reveal information about the time evolution of the vibrational wave functions in the intermediate core-excited state on the time scale of a few femtoseconds. Thus, these experiments probe the limits of the quantum mechanical description of the eigenstates of the molecular system integrated over the lifetime of the core hole.

Im Stadium limited disease werden bei nicht-vorbehandelten Patienten durch die Kombination von Chemotherapie und Radiotherapie objektiv mesbare Remissionen in einer Haufigkeit von 70-95% erzielt. Die medianen Uberlebensdauern der Patienten betragen 12 Monate, bei kompletten Remissionen 15-20 Monate. Nach 2 Jahren leben jedoch nur noch 5-10% der Patienten rezidivfrei. Bei den nicht-kleinz. Bronchialkarzinomen hat die Chemotherapie im Stadium IV mit Remissionsraten zwischen 25-45% ausschlieslich palliativen Charakter. Neue Ergebnisse im Stadium III mit Remissionsraten zwischen 50-70% ergeben Ansatze fur eine praoperative Induktionschemoth. bzw. einen erneuten Versuch der adjuvanten Chemotherapie.

We prospectively studied 35 patients with degenerative spinal canal stenosis and functional disorders using a new MRI procedure that allows demonstration of movement in the cervical spine, a 1.0T whole-body MR system. The patients were positioned in a Helmholtz neck coil, with special device for measuring different positions of the neck. T2-weighted single-shot HASTE sagittal images were acquired. For display the images were loaded into a cine loop. Our experience shows that functional aspects play an important role in bony canal stenosis as well as in movement disorders.

CT cisternography was compared with a new MRI method, so-called MR cisternography, to detect cerebrospinal fluid (CSF) fistulae in patients with posttraumatic and postoperative dural lesions. The MRI examinations were performed using a 1.0T whole-body system. A strongly T2*-weighted 3D-PSIF sequence and a 3D-CISS sequence were in the coronal plane. We examined 30 patients with CSF fistulae, and the results of the CT and MRI methods were compared and assessed with respect to intraoperative findings. The sensitivity of the MRI technique was higher than that of CT cisterno graphy. MR cisternography was also possible in patients without rhinorrhoea.

We compared two MR angiography (MRA) techniques, time-of-flight (TOF) and phase-contrast (PC), with digital substraction angiography (DSA), in relation to operative findings in 40 patients with cerebrovascular disease. The investigations were performed using a 1.5 T whole-body system. 2D- and 3D-TOF and 2D- and 3D PC sequences were used in sagittal and axial planes. Velocity-encoding of the PC sequence varied between 5 and 100 cm/ s, depending on the blood flow velocity. The 3D data-sets were analysed using a maximum intensity projection program. The sensitivity of TOF and PC is comparable with that of DSA in the diagnosis of venous thrombosis. MRA may be superior to DSA in patients with giant aneurysms.

Coincidence studies between Auger electrons and ions produced in the decay of a core hole excited state in free molecules reveal the individual pathways of soft x-ray induced fragmentation processes. We are able to identify the electronic configuration leading to stable or unstable ionic states. Measuring the kinetic energy of the ions, we also get data about the potential energy curves of the electronic states populated in the Auger decay of the core hole.