University of Twente Student Theses


Quantifying cerebral blood flow of both the micro- and macrovascular system using perfusion computed tomography

Jong, S.F. de (2015) Quantifying cerebral blood flow of both the micro- and macrovascular system using perfusion computed tomography.

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Abstract:Introduction: Patients with acute brain injury (ABI) may have insufficient cerebral blood flow (CBF), with the CBF deficit varying per brain region. The brain is very sensitive to hypoxic and ischemic states and therefore it is of great importance to monitor the CBF. Currently, no valid modality is available for that purpose. CT perfusion (CTP) is promising, but solely used qualitatively to distinguish ischemic and infarcted tissue from healthy tissue. Study aim: The primary goal of this study was to enhance and improve the current quantitative analysis possibilities of CTP in both the macro- and the microvascular system. Methods: This was achieved by 1) the development of the direct-flow model to calculate CBF velocity (CBFv) in the macrovascular system. This model was based on the principle that CBFv is the quotient of the distance between points in a vessel and the time delay of bolus arrival between those points. 2) The model was validated by conducting three short studies. Digital simulation data was used to determine CTP properties required to use the model; a flow phantom was used to test the model in a controlled setting; and the reliability was studied with in vivo data. For the microvascular system 3) normal values were derived of the perfusion parameters CBF, cerebral blood volume (CBV) and mean transit time (MTT) in the anterior, medial, posterior and basal ganglia flow territory in grey and white matter. Normal values were derived from subjects with an indication for CTP, but without the diagnosis of TIA or stroke. CTP data was acquired according to the best combination of processing steps. 4) The normal values were compared to perfusion values of patients with TIA and ischemic stroke. Results: 1) the direct flow principle was developed successfully, but 2) was not reliable. The flow phantom showed severe overestimation of the true flow velocity and in vivo data revealed negative CBFv. 3) Normal values were derived successfully, but showed large variance. 4) A significant difference was found between the MTT in the medial flow territory of normal subjects and ischemic stroke patients. Conclusion: CTP has the perspective to become a reliable tool to monitor CBF quantitatively in both the macro- and the microvascular system. However, the direct-flow model should be improved before introduction in clinical practice. To establish reliable normal values sample sizes should be enlarged and CTP data processing should be optimized.
Item Type:Essay (Master)
Radboud UMC, Nijmegen, Netherlands
Radboud UMC, Nijmegen, Netherlands
Faculty:TNW: Science and Technology
Subject:44 medicine
Programme:Technical Medicine MSc (60033)
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