In-vitro-Studie zur maschinellen Aufbereitung gekrümmter Wurzelkanäle humaner Molaren mit dem Endo IT control, dem Tecnika-Vision und dem Dentaport unter Anwendung von FlexMaster-Instrumenten mittels einer modifizierten Bramante-Technik

Durch die zunehmende Weiterentwicklung maschineller Aufbereitungssysteme im Fachbereich der Endodontie ist es notwendig, diese Systeme auf ihre klinische Effizienz hin zu untersuchen, bevor sie am Patienten angewendet werden. In dieser Studie wurden drei drehmomentbegrenzte Endodontiemotoren zur maschinellen Wurzelkanalaufbereitung der Firmen Vereinigte Dentalwerke (München), J Morita (Japan) und ATR (Italien) miteinander verglichen. Dabei wurden alle Motoren mit FlexMaster-Instrumenten (VDW, München) betrieben. Bei der Untersuchungsmethode wurde eine Modifikation der BRAMANTE-Technik angewandt. Die Wurzelkanalaufbereitung erfolgte nach der "Crown-down"-Methode. Ziel dieser Studie war es, einen quantitativen Vergleich des unbehandelten und des aufbereiteten Wurzelkanalquerschnitts durch digitalisierte Abbildungen unter mikroskopischer Vergrößerung möglichst detailgenau zu erfassen und anschließend computerunterstützt eine präzise quantitative Auswertung der Effizienz der einzelnen Systeme vorzunehmen. Vor allen Dingen sollte die Präzision der Aufbereitung nicht nur in der apikalen Region überprüft werden, sondern auch in weiteren Bereichen des Wurzelkanals. Von den in Polyacrylatblöcken fixierten Zähnen wurden je sieben horizontale Schnitte (Durchmesser: 1,5 mm), beginnend vom Apex, ähnlich der Technik von BRAMANTE, angefertigt. Vor und nach der Wurzelkanalaufbereitung wurden alle Wurzelkanalquerschnitte mittels analoger Fotografie (CCD Kamera/Kappa Messtechnik) und unter 12-facher makroskopischer Vergrößerung (Makroskop Wild M420, Hersteller: Leica) aufgezeichnet. Damit die große Anzahl der Bilder Software-unterstützt vermessen werden konnte, mussten die analogen Bilddaten digitalisiert werden. Die Konvertierung der analogen Daten erfolgte mit der "Hollywood-Bridge" (Hersteller: Dazzle). Zur Vermessung der Flächen wurde ein Software-Programm der NASA (Image 2000) verwandt. In allen drei Versuchsgruppen wurden n = 20 Kanäle aufbereitet. Die erste Versuchsgruppe wurde mit dem Endo IT control, die zweite Versuchsgruppe mit dem Tecnika-Vision und die dritte mit dem Dentaport aufbereitet und miteinander verglichen. Die Gruppen Endo IT control und Tecnika-Vision wiesen für den durchschnittlichen Substanzabtrag nahezu identische Mittelwerte von 0,114 mm2 auf. Bei der Gruppe Dentaport ergab sich neben dem niedrigsten Mittelwert für den durchschnittlichen Substanzabtrag gleichzeitig der geringste Mittelwert von 570,15 sec. für die Aufbereitungszeit. Verluste an Arbeitslängen sind bei allen Systemen aufgetreten, wobei die Gruppe Tecnika-Vision mit 16 Fällen die meisten Verluste zu verzeichnen hatte. In der vorliegenden Studie sind insgesamt 17 FlexMaster-Feilen frakturiert, hierbei fiel die Gruppe Tecnika-Vision mit sieben Instrumentenbrüchen auf. Die Mittelwerte der Gruppen unterschieden sich jedoch nur geringfügig, sodass sich keine signifikanten Unterschiede bei den statistischen Tests ergaben. Die Aufbereitung der Wurzelkanäle wurde ausschließlich mit FlexMaster-Feilen durchgeführt. Für den Abtrag scheinen die Geometrie des Instruments und die Beschaffenheit der Schneide wichtiger zu sein als die Wahl des Motors. In dieser Studie wurde der Gesamtabtrag nach Aufbereitung ermittelt. Dabei blieb unberücksichtigt, ob der Materialabtrag gleichmäßig erfolgte

Automated VOI Analysis in FDDNP PET Using Structural Warping: Validation through Classification of Alzheimer's Disease Patients

We evaluate an automated approach to the cortical surface mapping (CSM) method of VOI analysis in PET. Although CSM has been previously shown to be successful, the process can be long and tedious. Here, we present an approach that removes these difficulties through the use of 3D image warping to a common space. We test this automated method using studies of FDDNP PET in Alzheimer's disease and mild cognitive impairment. For each subject, VOIs were created, through CSM, to extract regional PET data. After warping to the common space, a single set of CSM-generated VOIs was used to extract PET data from all subjects. The data extracted using a single set of VOIs outperformed the manual approach in classifying AD patients from MCIs and controls. This suggests that this automated method can remove variance in measurements of PET data and can facilitate accurate, high-throughput image analysis

Brain Imaging with Positron Emission Tomography: Quantification and Biomedical Applications in Alzheimer's Disease and Brain Tumors

Positron emission tomography (PET) is a unique and powerful imaging technique that is used to visualize and quantify various biological processes in living subjects in health and disease. PET imaging can also provide biological information for the assessment of therapies. In this dissertation, we will cover three projects that utilize the quantitative capability of PET for studying two neurological disorders: Alzheimer's disease and brain tumors.One of the goals in PET imaging is to produce an image volume that accurately describes the true distribution of the injected radioactivity. The correction factor that has the most significant impact on the quantitative aspects of a PET image is attenuation correction. Without it, the reconstructed images will give a distorted view of the true activity distribution. Head movement during a PET scan (especially a dynamic scan) can also lead to a loss in the information content contained in a PET image. This is especially true when scanning patients with dementia or movement disorders. The transmission scan, which is typically acquired at the start of a PET study, corrects for photon attenuation in each of the serial emission scans that are acquired afterwards.In the first project of this dissertation, we developed a retrospective image-based movement correction (MC) method and evaluated its implementation on dynamic 18F-FDDNP PET images of cognitively intact control subjects and patients with Alzheimer's disease (AD), each with varying degrees of head movement. 18F-FDDNP is a PET probe that binds to beta-amyloid plaques and neurofibrillary tangles, the neuropathological hallmarks of AD. The MC method corrected for transmission-emission misalignments as well as for emission-emission misalignments that might have been present in the dynamic PET scan. The image quality, tracer kinetics, and diagnostic accuracy of the 18F-FDDNP PET images were significantly improved after applying the MC method.In the second project of this dissertation, we investigated whether changes in 18F-FLT kinetic parameters, taken early after the start of therapy, could predict overall survival and progression-free survival in patients with recurrent malignant glioma undergoing treatment with bevacizumab (an angiogenesis inhibitor) and irinotecan (a chemotherapeutic agent). 18F-FLT is a radiotracer used in PET to measure cellular proliferation. We found that when a group of optimal kinetic parameter changes are incorporated into a linear discriminant function, one could accurately classify patients into their known survival groups. This method is advantageous because by reliably identifying short- and long-term survivors early during therapy, clinicians can discontinue ineffective treatment strategies and switch to more advanced treatment regimens that could improve patient outcome.Our third project expanded on what we did in our second project in that we acquired longitudinal 18F-FDOPA PET scans in addition to 18F-FLT PET scans. We also tried to predict overall survival as a continuous outcome variable using multiple linear regression (as opposed to a dichotomous categorical variable with discriminant analysis from before). In brain tumors, 18F-FDOPA is used to image amino acid transport. We found that in patients with recurrent malignant glioma, kinetic information from 18F-FLT alone was more predictive than using information from 18F-FDOPA alone. Using both probes combined provided comparable results to using 18F-FLT alone, suggesting that a single tracer may provide sufficient information for predicting OS with reasonable accuracy.The studies reported in this dissertation have demonstrated in three examples that the utility of kinetic quantification can significantly improve the value of PET for imaging biological functions in brain tissues in vivo. The developed methodologies in these examples are also expected to be useful in other quantitative brain PET imaging studies – for other applications or using other tracers

Community-Driven Development or community-based development?

Review of Norwegian-funded CDC projects in Afghanista

Annex 2-4: Norway's contribution to women's participation in peacebuilding A Case Study Analysis from Afghanistan, Colombia and Nordic Women Mediators Network

The study is part of an evaluation of Norwegian efforts to increase women's participation in peacebuilding between 2000 - 2020 conducted by Norad’s evaluation department. The purpose is to generat e knowledge on how Norway has supported women’s participation in peace efforts and what the effects of this support have been. The case study analysis has brought together findings from country cases on Afghanistan and Colombia, and of the “Nordic Women Me diators N etwork” (NWM) on how Norway has worked to promote women’s participation in peace processes globally . In Afghanistan the focus has been on women ’ s participation in peace initiatives, in Colombia it has been on women ’ s participation in the implement ation of the Peace Agreement, and with the NWM it has support to women's participation in p eace negotiations around the world

Automated movement correction for dynamic PET/CT images: evaluation with phantom and patient data.

Head movement during a dynamic brain PET/CT imaging results in mismatch between CT and dynamic PET images. It can cause artifacts in CT-based attenuation corrected PET images, thus affecting both the qualitative and quantitative aspects of the dynamic PET images and the derived parametric images. In this study, we developed an automated retrospective image-based movement correction (MC) procedure. The MC method first registered the CT image to each dynamic PET frames, then re-reconstructed the PET frames with CT-based attenuation correction, and finally re-aligned all the PET frames to the same position. We evaluated the MC method's performance on the Hoffman phantom and dynamic FDDNP and FDG PET/CT images of patients with neurodegenerative disease or with poor compliance. Dynamic FDDNP PET/CT images (65 min) were obtained from 12 patients and dynamic FDG PET/CT images (60 min) were obtained from 6 patients. Logan analysis with cerebellum as the reference region was used to generate regional distribution volume ratio (DVR) for FDDNP scan before and after MC. For FDG studies, the image derived input function was used to generate parametric image of FDG uptake constant (Ki) before and after MC. Phantom study showed high accuracy of registration between PET and CT and improved PET images after MC. In patient study, head movement was observed in all subjects, especially in late PET frames with an average displacement of 6.92 mm. The z-direction translation (average maximum = 5.32 mm) and x-axis rotation (average maximum = 5.19 degrees) occurred most frequently. Image artifacts were significantly diminished after MC. There were significant differences (P<0.05) in the FDDNP DVR and FDG Ki values in the parietal and temporal regions after MC. In conclusion, MC applied to dynamic brain FDDNP and FDG PET/CT scans could improve the qualitative and quantitative aspects of images of both tracers