| Summary: | 碩士 === 國立陽明大學 === 生物醫學影像暨放射科學系暨研究所 === 98 === Dynamic susceptibility contrast magnetic resonance imaging is a technique for measuring cerebral blood perfusion. Quantitative calculations on the hemodynamic parameters such as cerebral blood volume ( CBV ) 、 cerebral blood flow ( CBF ) 、and mean transit time ( MTT ) are used for the diagnosis of cerebral vascular diseases, such as stenosis and acute ischemic stroke.
Computer simulation was used to evaluate the effect of tracer delay on the quantification of CBF and MTT using different calculation techniques, including ： Maximum slope、Maximum concentration、Fourier transform、standard singular value decomposition ( sSVD ), and circular singular value decomposition ( cSVD ). Scatter plots were used to evaluate parameters calculated for different tissues using these algorithms from clinical images in patients with stenosis. The four tissue types determined from the independent component analysis segmentation were artery on the normal and stenosis sides, and brain parenchyma on the normal and stenosis sides.
Our simulation results indicate that：1) CBF were underestimated for short MTTs in all calculation techniques；2) sSVD is sensitive to tracer time delay；3) MTT_sSVD may provide high contrast for clinical diagnosis；4) CBF and MTT calculated by Maximum slope and Maximum concentration algorithms are similar to cSVD. The Maximum concentration algorithm is not only less sensitive to noise, but also easy to calculate without any complicated calculation. Scatter plot analysis of clinical images indicate that：1) the CBF_sSVD values for artery and brain parenchyma at the normal side were higher than CBF_cSVD values； 2) the MTT _sSVD values for artery and brain parenchyma at the abnormal side were longer than MTT _cSVD values； 3) MTT _sSVD may provide high contrast for clinical images in patients with stenosis.
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