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Biomedical subjects

D Schulze

Publications and source records attributed to D Schulze.

At least 19 recordsLinked to original sources
PubMed2006

Stability of liquid metal drops affected by a high-frequency magnetic field.

The dynamic behavior of liquid metal drops submitted to a high-frequency magnetic field is investigated experimentally. The motivation for this study comes from the coating industry. In this industry, liquid metals showing a free surface held in a dome-type shape are evaporated by applying electromagnetic pressure. The Galinstan drops are placed on a curved glass plate. A ringlike inductor fed by an alternating electrical current generates the magnetic field. The surface contour of the drop is observed using a high-speed camera system. The data are analyzed by utilizing image processing methods. In the experiment, we vary the inductor current I and the drop volume V while the frequency is fixed at 20 kHz . Upon increasing the inductor current within the range 0 I(C), these symmetric states become unstable to capillary waves. The critical current (critical electromagnetic Bond number) as well as the critical mode number, the critical frequency, and the amplitudes of the waves depend strongly on the volume (Bond number).

Journal Article↗
PubMed2006

Orthodontic springs and auxiliary appliances: assessment of magnetic field interactions associated with 1.5 T and 3 T magnetic resonance systems.

The objective of this paper is to evaluate magnetic field interactions at 1.5 and 3 T for 20 orthodontic devices used for fixed orthodontic therapy. Twenty springs and auxiliary parts made from varying ferromagnetic alloys were tested for magnetic field interactions in the static magnetic field at 1.5 and 3 T. Magnetic translational force F(z) (in millinewtons) was evaluated by determining the deflection angle beta [American Society for Testing and Materials (ASTM standard test method)]. Magnetic-field-induced rotational force F(rot) was qualitatively determined using a five-point scale. beta was found to be >45 degrees in 13(15) devices at 1.5(3) T and translational force F(z) exceeded gravitational force F(g) on the particular object [F(z) 10.17-261.4 mN (10.72-566.4 mN) at 1.5(3) T]. F(z) was found to be up to 24.1(47.5)-fold higher than F(g) at 1.5(3) T. Corresponding to this, F(rot) on the objects was shown to be high at both field strengths (> or = +3). Three objects (at 1.5 T) and one object (at 3 T) showed deflection angles <45 degrees , but F(rot) was found to be > or = +3 at both field strengths. For the remaining objects, beta was below 45 degrees and torque measurements ranged from 0 to +2. Of 20 objects investigated for magnetic field interactions at 1.5(3) T, 13(15) were unsafe in magnetic resonance (MR), based on the ASTM criteria of F(z). The implications of these results for orthodontic patients undergoing MRI are discussed.

Electromagnetic Fields↗
PubMed2006

Diagnostic criteria for the detection of mandibular osteomyelitis using cone-beam computed tomography.

OBJECTIVES: To investigate the usefulness of cone-beam computed tomography (CBCT) in cases of suspected osteomyelitis (OM) of the mandible. METHODS: 13 patients with clinical suspected OM of the mandible underwent cone-beam computed tomography with the NewTom QR-DVT 9000. After CBCT revealed signs confirming the diagnosis of OM, biopsies were performed. Only cases in which histology confirmed the OM were included in this study. RESULTS: CBCT sufficiently depicts OM-typical lesions like osteolytic and osteosclerotic areas as well as periosteal reaction, ill-defined cortical borders and sequestra. CONCLUSIONS: Because the local extension of the disease and its relationship to anatomic structures can be sufficiently detected by CBCT, we see an important additional indication for the usage of CBCT. With regard to distinct cases CBCT combined with scintigraphy seems to be a sufficient diagnostic strategy concerning suspected OM.

Adolescent↗
PubMed2005

Intraoperative imaging of zygomaticomaxillary complex fractures using a 3D C-arm system.

After preclinical studies and evaluation of radiation exposures, intraoperative three-dimensional (3D) C-arm based imaging is now available for the facial skeleton. Fourteen patients admitted for surgical treatment of zygomaticomaxillary complex (ZMC) fractures were included in the study. Preoperative diagnostics and surgical treatment were performed as usual. Intraoperatively, after open reduction, a cone-beam computed tomography (CBCT) dataset was generated using the SIREMOBIL Iso-C3D (Siemens Medical Solutions, Erlangen, Germany). After DICOM-import in eFilm Workstation axial, coronal and sagittal reconstructions were evaluated by five examiners with the help of six defined criteria. In our study, secondary reconstructions were available after 6 min, excluding the time needed for the evaluation of the images. Especially the positioning of the isocentre of the SIREMOBIL Iso-C3D proved to be uncomplicated. Because of the size of the datasets, assessment of the symmetry of the malar projection proved difficult. Best scoring results were found regarding the visualization of the fragment position, bony anchorage of the screws and the fitting of the plates. Remarkable was the low level of metal artefacts in primary and secondary reconstructions. In conclusion, our results demonstrate intraoperative CBCT using the SIREMOBIL Iso-C3D suitable for assessment of postoperative results following ZMC reduction.

Adult↗
PubMed2004

[Virtual simulation of dental surgery using a three-dimensional computer model with a force feedback system].

BACKGROUND: Selective reduction of bone without injuring inner structures is an essential part of surgical techniques, especially during dental surgery. Virtual drilling is possible using a new simulator. The following illustrates simulation of an apicectomy. MATERIAL AND METHODS: Using the VOXEL-MAN system, a virtual three-dimensional model of a skull was created based on CT data. Both inferior alveolar nerves and apical inflammations of teeth 23, 25, 36, and 35 were virtually simulated. To achieve a realistic drilling effect with the force feedback system, special tools were integrated into VOXEL-MAN to obtain a high resolution of collision recognition. Adding drilling noises further improved the simulation. Spatial 3D perception was possible with the help of shutter glasses. RESULTS: The presented computer model enabled the visual and haptic observation of complex volume-based models and virtual interaction with them. The haptic feeling proved to be convincing because of collision recognition, consideration of drilling parameters, and addition of drilling noises. Via postoperative reconstructions, polydimensional verification of performed drilling routes is possible. CONCLUSION: Using apicectomies as examples, realistic simulation of dental surgical procedures, even in complex anatomical models, is possible. Generally, it is possible to add virtual pathologies in data sets and/or to use anonymous patient data sets to extend the range of simulated surgical procedures.

Apicoectomy↗
PubMed2004

[Radiation exposure and 3 dimensional imaging options of SIREMOBIL Iso-C(3D) for planning surgical dental interventions].

BACKGROUND: Preoperative dental X-ray diagnostics of multimorbid, non compliant patients requiring dental surgery are often insufficient. The SIREMOBIL Iso-C(3D) has made intraoperative 3D imaging available, even for the facial skeleton. This modality was used intraoperatively in two patients referred for surgical dental treatment. Furthermore, radiation exposure of the SIREMOBIL Iso-C(3D), an orthopantomography and a complete dental status was compared. MATERIAL AND METHODS: An Alderson-Rando phantom was exposed to ten cycles of the SIREMOBIL Iso-C(3D) using the fast mode (50 projections). In comparison 28 panoramic views of an Orthophos and 10 sets of 14 dental images using the Oralix DC with a quadrate mask were applied. Twenty-five anatomically defined TLD positions were analyzed. Furthermore, SIREMOBIL Iso-C(3D) was used in one patient by performing 100 projections and in a second patient by performing 50 projections. After DICOM-import in eFilm, axial, coronal, and sagittal reconstructions were evaluated by five examiners regarding defined criteria. RESULTS: The radiation exposure level of the SIREMOBIL Iso-C(3D) was lower than in the complete dental status and only slightly higher in comparison with the orthopantomography, although the system requires the highest number of single projections. Quantitative evaluation of the visualization and recognition of defined structures proved to be very good and good in most points. However, limitations of the system became obvious regarding apical processes. CONCLUSION: Because of the dosimetry results and the visualization of the relevant structures, in patients for whom preoperative images cannot sufficiently be performed, the intraoperative use of the SIREMOBIL Iso-C(3D) as a base examination is justified.

Adult↗
PubMed2004

Intraoperative 3D imaging of the facial skeleton using the SIREMOBIL Iso-C3D.

OBJECTIVES: With respect to high-contrast structures, cone beam computed tomography (CBCT) offers an alternative imaging modality to computed tomography (CT), requiring less radiation exposure. The C-arm system SIREMOBIL Iso-C3D for three-dimensional (3D) reconstruction has made this modality available for intraoperative use. This paper presents the first intraoperative images of the facial skeleton using the SIREMOBIL Iso-C3D. METHODS: Cases of a zygomaticomaxillary complex fracture, a mandibular angle fracture and a bimaxillary repositioning osteotomy are described to demonstrate the application possibilities of this system in maxillofacial surgery. RESULTS: In addition to the uncomplicated handling of the SIREMOBIL Iso-C3D, generally important was the low level of metal artefacts in its primary and secondary reconstructions, even in close proximity to the material. However, it has to be kept in mind that while soft tissues are visualized using CBCT, information about soft tissue quality cannot be obtained. CONCLUSION: The SIREMOBIL Iso-C3D generates intraoperative data sets suitable for the visualization of the facial bones after open reduction of fractures.

Adolescent↗
PubMed2004

Radiation exposure during midfacial imaging using 4- and 16-slice computed tomography, cone beam computed tomography systems and conventional radiography.

OBJECTIVES: Radiation doses were determined to balance risks against usefulness of the different modalities available for the imaging of the facial skeleton. METHODS: An Alderson Rando Phantom, armed with lithium fluoride thermoluminescent dosemeters (TLDs) was exposed using a set of four conventional radiographs (orbital view, modified Waters view, orthopantomography, skull posterior--anterior 0 degrees ), two different cone beam computed tomography (CBCT) (NewTom 9000 and Siremobil Iso-C3D), and multislice computed tomography (CT) modalities (Somatom VolumeZoom and Somatom Sensation 16). TLDs from 14 well defined anatomical sites lying within the primary beam as well as the TLD corresponding to the thyroid gland were evaluated. RESULTS: Multislice CT showed the highest exposure values. Exposure levels of the CBCT systems lay between CT and conventional radiography. Dose measurement for the 16-slice CT revealed nearly the same radiation exposure as the 4-slice system when adapted examination protocols were used. CONCLUSIONS: Selection of the most appropriate imaging modality should be performed in view of the delivered doses, required image quality and information and the clinical circumstances.

Facial Bones↗
PubMed2004

Diagnostic advantages and possibilities for secondary reconstruction of NewTom 9000 data sets using eFilm.

In order to facilitate diagnosis of images generated with the NewTom 9000, the professional DICOM viewer eFilm Workstation was used for evaluation. Primary reconstructions of patient data of one hundred NewTom 9000 examinations were exported to the DICOM format and subsequently imported in the DICOM viewer eFilm Workstation. Multiplanar reconstructions (MPR) and three-dimensional reconstructions were computed for diagnostic purposes. All desired perspectives can be viewed with this software with CT-like printouts, offering several additional features and an uncomplicated print modus. The DICOM viewer eFilm Workstation is an easy-to-use alternative to the standard software provided by quantitative radiology.

Computer Systems↗
PubMed2003

[3-dimensional imaging possibilities of thhe mid-face area using digital volume tomography based on a daver study of angle stable osteosynthesis].

BACKGROUND: Multidirectional angularly stable interlocking plate systems are now available for the surgical treatment of the midface. After first experiences in cases of mandibular fractures, application to the facial skeleton was investigated using a cadaver study. Furthermore, three-dimensional imaging by means of the digital volume tomograph NewTom DVT 9000 after reduction of orbitozygomatical fractures was performed and evaluated. MATERIAL AND METHODS: After artificial osteotomy and reduction of both zygomatical complexes, osteosynthesis of the left side was performed with three 4-hole miniplates (2.0). On the right side, three angular stable 2-hole plates (2.3) were used. Thereafter, a three-dimensional data set was generated using the NewTom DVT 9000. After DICOM-import in eFilm reconstructions were evaluated by six examiners regarding defined criteria. RESULTS: After adaptation and fixation of the angular stable interlocking plate system without complications, manual checking revealed that the primary stability did not seem inferior to the other side. Defined criteria were sufficiently evaluable, even close to the osteosynthetic material, using reconstructions of the digital volume tomography data set. CONCLUSION: Surgical treatment of midfacial fractures using a multidirectional angularly stable interlocking plate system seems promising. The NewTom DVT 9000 proved to be suitable to visualize even fine osseous structures of the midface.

Bone Plates↗
PubMed2003

3D-imaging of the facial skeleton with an isocentric mobile C-arm system (Siremobil Iso-C3D).

OBJECTIVES: The purpose of this study was to compare three-dimensional (3D) imaging of the facial skeleton using an isocentric mobile C-arm system vs CT. METHODS: A dried human skull was scanned using a Siremobil Iso-C3D and a multi-detector CT (SOMATOM Volume Zoom; Siemens Medical Solutions, Erlangen, Germany) to compare reconstructed data sets. For each group of scans a standard protocol and a high resolution protocol were used. Image quality was analysed using six anatomical and six virtual structures in the primary reconstructed axial images of both data sets of the Siremobil Iso-C3D compared with CT. A receiver operating characteristic (ROC) study was performed with six examiners. RESULTS: The original categorical response data revealed no significant differences in sensitivity and specificity (P < 0.05). However, image quality of the reconstructed images of the Siremobil Iso-C3D was inferior to the CT images, with metal artefacts having a more prominent negative effect. CONCLUSIONS: The Siremobil Iso-C3D produces 3D images of the facial skeleton suitable for imaging osseous structures. No significant differences were found in sensitivity or specificity between the two methods. Metal objects degrade the image from the Iso-C method to a greater extent than those from CT.

Artifacts↗
PubMed2003

Digital transversal slice imaging in dental-maxillofacial radiology: from pantomography to digital volume tomography.

With digital transversal slice imaging (TSI) as a supplementary program to pantomographic devices and digital volume tomography (DVT), images of the viscerocranium are now possible in several planes. The two procedures, TSI and DVT, are complementary. They should be applied where the indication justifies it in dentistry and maxillofacial surgery for diagnostic and forensic purposes. To minimize patient exposure to radiation, computer tomography (CT) should only be used in complex situations of the viscerocranium where soft tissues are involved or in tumor diagnosis.

Facial Bones↗
PubMed2003

A comparison of two intraoral CCD sensor systems in terms of image quality and interobserver agreement.

PURPOSE: Two intraoral CCD sensor systems were compared with respect to image quality and interobserver agreement. MATERIALS AND METHODS: Forty intraoral images from each of the sensors (Trophy RVG5, Sirona Sidexis) were examined by 4 observers in terms of anatomical landmarks and general image quality. The images were divided into 2 groups--filtered and unfiltered. Kappa values for interobserver agreement were calculated for all assessed points. RESULTS: The Trophy sensor showed better image quality in the filtered group, and the Sirona sensor demonstrated good image quality in the unfiltered group. Moderate to substantial interobserver agreement was achieved. The use of filters increased edge artefacts. Sensor specific artefacts in the Trophy system were observed.

Artifacts↗
PubMed2002

[Evaluation of TSE- and T1-3D-GRE-sequences for focal cartilage lesions in vitro in comparison to ultrahigh resolution multi-slice CT].

PURPOSE: Evaluation of TSE- and T 1 -3D-GRE-sequences for focal cartilage lesions in vitro in comparison to ultrahigh resolution multi-slice CT. MATERIALS AND METHODS: Forty artificial cartilage lesions in ten bovine patellae were immersed in a solution of iodinated contrast medium and assessed with ultrahigh resolution multi-slice CT. Fat-suppressed TSE images with intermediate- and T 2 -weighting at a slice thickness of 2, 3 and 4 mm as well as fat-suppressed T 1 -weighted 3D-FLASH images with an effective slice thickness of 1, 2 and 3 mm were acquired at 1.5 T. After adding Gd-DTPA to the saline solution containing the patellae, the T 1 -weighted 3D-FLASH imaging was repeated. RESULTS: All cartilage lesions were visualised and graded with ultrahigh resolution multi-slice CT. The TSE images had a higher sensitivity and a higher inter- and intraobserver kappa compared to the FLASH-sequences (TSE: 70 - 95 %; 0.82 - 0.83; 0.85 - 0.9; FLASH: 57.5 - 85 %; 0.53 - 0.72; 0.73 - 0.82, respectively). An increase in slice thickness decreased the sensitivity, whereby deep lesions were even reliably depicted on TSE images at a slice thickness of 3 and 4 mm. Adding Gd-DTPA to the saline solution increased the sensitivity by 10 % with no detectable advantage over the T 2 -weighted TSE images. CONCLUSION: TSE sequences and application of Gd-DTPA seemed to be superior to T 1 -weighted 3D-FLASH sequences without Gd-DTPA in the detection of focal cartilage lesions. The ultrahigh resolution multi-slice CT can serve as in vitro reference standard for focal cartilage lesions.

Animals↗
PubMed2001

Subcellular localization analysis of the closely related Fps/Fes and Fer protein-tyrosine kinases suggests a distinct role for Fps/Fes in vesicular trafficking.

The subcellular localizations of the Fps/Fes and closely related Fer cytoplasmic tyrosine kinases were studied using green fluorescent protein (GFP) fusions and confocal fluorescence microscopy. In contrast to previous reports, neither kinase localized to the nucleus. Fer was diffusely cytoplasmic throughout the cell cycle. Fps/Fes also displayed a diffuse cytoplasmic localization, but in addition it showed distinct accumulations in cytoplasmic vesicles as well as in a perinuclear region consistent with the Golgi. This localization was very similar to that of TGN38, a known marker of the trans Golgi. The localization of Fps/Fes and TGN38 were both perturbed by brefeldin A, a fungal metabolite that disrupts the Golgi apparatus. Fps/Fes was also found to colocalize to various extents with several Rab proteins, which are members of the monomeric G-protein superfamily involved in vesicular transport between specific subcellular compartments. Using Rabs that are involved in endocytosis (Rab5B and Rab7) or exocytosis (Rab1A and Rab3A), we showed that Fps/Fes is localized in both pathways. These results suggest that Fps/Fes may play a general role in the regulation of vesicular trafficking.

Animals↗
PubMed2000

Aluminium phosphate adjuvants prepared by precipitation at constant pH. Part I: composition and structure.

Aluminium phosphate adjuvant was precipitated under constant pH conditions in an effort to characterize materials formed at defined precipitation conditions. A reaction vessel was designed to provide a continuous steady-state process. An aqueous solution containing aluminium chloride and sodium dihydrogen phosphate was pumped into the reaction vessel at a constant rate. A second pump infused a sodium hydroxide solution at the rate required to maintain the desired pH. Precipitations were performed between pH 3.0 and 7.5, at intervals of pH 0.5. The adjuvants were characterized using 27Al NMR, FTIR, Raman and X-ray diffraction methods along with elemental analysis. The results of this study indicate that a continuum of amorphous aluminium hydroxyphosphates were formed having properties that changed as a continuous function of the precipitation pH. The phosphate content decreased as the pH of precipitation increased. 27Al NMR spectra revealed that the majority of the aluminium was octahedrally coordinated, with a small percentage of tetrahedrally coordinated aluminium. The density of the adjuvants was directly related to the pH of precipitation. The most prominent feature of the IR and Raman spectra is the P-O stretching vibration of the structural PO(4) groups. The positions of these bands decreased linearly as the precipitation pH increased. The results of selective deuteration FTIR experiments are consistent with high surface area materials as most of the OH groups were exposed near the surface of the adjuvant.

Adjuvants, Immunologic↗
PubMed2000

Aluminium phosphate adjuvants prepared by precipitation at constant pH. Part II: physicochemical properties.

The impact of the pH of precipitation on the physicochemical properties of aluminium phosphate adjuvants was investigated by precipitating aluminium phosphate adjuvants under constant pH conditions at pH values from 3.0 to 7.5 at intervals of 0.5. The pH of precipitation did not affect the morphology, but the point of zero charge (PZC) and rate of acid neutralization varied directly with pH of precipitation. Aggregation and protein adsorption capacity exhibited a parabolic relationship to the pH of precipitation. Minimum protein adsorption and maximum aggregation were observed at pH 5.5. In contrast to adjuvants precipitated from the same reactants but under uncontrolled pH conditions, the pH of all of the adjuvants precipitated under constant pH conditions remained constant for a 3-month aging period at room temperature.

Adjuvants, Immunologic↗