T. Meissner. Adaption and Partitioning of a Brain Geometry for Spatially Detailed Calculation of Local Cerebral Temperatures. Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT). Masterarbeit. 2019
Stroke is the third most common cause of death in western society and its number is in- creasing due to demographic change. Mechanical thrombectomy is a standard therapy for ischemic stroke patients, where the blood clot is removed in a minimal-invasive surgery. In addition to thrombectomy, the induction of selective therapeutic hypothermia through direct blood cooling was suggested, as it provides neuroprotection to the brain. For realistic simulations of cerebral temperature distribution, the finely meshed brain model Colin27 was coupled to a pre-existing hemodynamic model. The cerebrum is separated from the brainstem and cerebellum by manual segmentation of the MRI data. The Brain Vasculature Database was used in combination with a modified region growing algorithm and three-dimensional probability maps to produce perfusion territories of the major cerebral arteries. The next step was to subdivide the regions of the major cerebral arteries into terminal regions to assign each terminal artery from the hemodynamic model to one brain region. Vascularization patterns from literature and region growing were used to identify those terminal regions. A coarser version of the brain was set up for temporal simulation in COMSOL and an ischemic stroke was simulated by entirely blocking the blood flow in the right MCA M1 seg- ment. The cooling effect in the perfusion territories of the major cerebral arteries, including the impact to the body core temperature were analyzed. The simulations show, that direct blood cooling in the right Common Carotid Artery decreases the spatial average temperature in the affected hemisphere by 1.7◦C after 30 minutes of cooling, while the contralateral hemisphere stays nearly unaffected. The decrease in systemic body is insignificant. The results of this thesis indicated that mild therapeutic hypothermia is achievable in the penumbra through a cooling catheter, while the effect on the rest of the body was minimized. The simulation help to better understand and predict how selective brain cooling can be applied in stroke therapy.