Magnetic resonance based morphometric analysis of the tentorial notch

Background: The study of the tentorial notch can improve the understanding of brain injury mechanisms. Tentorial morphology has been analyzed primarily in cadaveric studies. However, the postmortem effect can cause variability in the measurements. The objective was to evaluate the morphometry of the tentorial notch and the third cranial nerve on living subjects using Magnetic Resonance Imaging (MRI). Materials and methods: A retrospective cross-sectional study was performed. Using consecutive cases, 60 MRI scans were analyzed for tentorial notch morphology. Maximum notch width (MNW), notch length (NL), interpedunculoclival (IC) distance, apicotectal (AT) distance, CN-III distance, and inter CN-III angle, were obtained. For the classification of the tentorial notch quartile distribution technique for MNW, NL, AT distance, and IC distance was used. Results: According to the quartile of the MNW, patients were stratified into narrow, midrange, and wide groups. Using the NL quartile groups, they were also classified as short, midrange, and long. With these, the tentorial notch could be classified into eight types. Statistical differences between genders in the MNW and inter CN-III angle were found, as well as a strong positive correlation between NL and AT distance, and between right and left CN-III distances. Conclusions: There were differences between the cadaveric samples and living subjects in the CN-III distances. This difference could be explained by the dehydration of brain volume in the postmortem process which may cause nerve elongation. Morphometry of the tentorial notch and its neurovascular relations allows a better understanding of the mechanisms of brain herniation

Imaging of myelin proteins during injury and differentiation

Myelin injury plays a role in many devastating conditions, including multiple sclerosis, and neuromyelitis optica. Previous work in understanding myelin injury has utilised a combination of high-resolution static imaging modalities, such as electron microscopy, and ensemble-averaged imaging, such as immunohistochemistry. Within the work presented in this thesis the behaviour of myelin basic protein was addressed, during various stages of differentiation and injury. In order to explore this several reporters for myelin basic protein were designed and encoded within Semliki forest constructs in order to induce protein transduction in oligodendroglial cells. Reporters utilised several fluorescent tags including Dendra2, mCherry, and GFP. These viral vectors were characterised to determine the expression kinetics and toxicity within cells. Following the production of the MBP reporters, a complement injury modality was optimised to induce myelin/oligodendrocyte specific injury with little injury within axons/neurones. This myelin injury was utilised for live imaging of myelin using the MBP reporters produced previously. The reporters produced were utilised to explore the change in particle dynamics following myelin injury, using single molecule TIRF imaging. Responses to injury were compared over various stages of oligodendrocyte differentiation, where it was found that MBP dynamics following injury varied most when mature oligodendrocytes were injured