在醫學領域中，磁振造影（Magnetic Resonance Imaging, MRI）因為具有良好的空間解析度及對比度，且不會對人體產生任何輻射性或侵入性的傷害，所以在疾病診斷中為經常被醫師們使用的輔助工具。其中利用磁振造影測量患者腦部血流情形所攝得之對比劑濃度與時間關係曲線圖，更是醫學界在對付腦血管病變（Brain Lesion）時的診斷利器。然而截至目前為止，我們尚未有一個較正確且快速的方法可以用來配適其對比劑濃度與時間關係曲線中的參數。所以在本論文中，我們嘗試以統計上的觀點，利用幾種不同的配適方法，找出與原始觀察值最為接近之估計值。
在本研究中使用的配適方法有—「迴歸分析法」、「Whittaker修勻法」、「非線性函數參數修勻法」及「核修勻法（Kernel Graduation）」。
本論文將以往醫學界慣用的「乘方性誤差項」改變為「加成性誤差項」，再以不同的誤差項，利用電腦模擬出各組假資料（Pseudo Data）後，以上述的四種方式對原始觀察值進行參數配適與函數估計。綜合模擬資料與真實資料所配適的比較結果，我們認為在幾種方法中，最穩健（Robust）的配適法是「Whittaker修勻法」。而在本論文中進行配適的真實資料，應該具有較大的誤差項，才導致非線性函數參數修勻法不能得出很好的估計值。 / With greater resolution, higher contrast and no radiative hurt to human body, Magnetic Resonance Imaging (MRI) is widely used by doctors in diagnosing diseases. The concentration of the contrast agent v.s. time curves which generated by MRI for cerebral blood flowing is very useful to doctors when giving treatments to brain lesion. However, we still have no precise and quick solution for fitting the curve of the concentration of the contrast agent vs. time. Therefore, this essay tries to use some different statistical fitting methods to find the closest estimates to the crude observations.
We will use four different fitting methods here—"Regression Analysis", "Whittaker Graduation", "Nonlinear Function Parametric Graduation", "Kernel Graduation".
This essaywill change the "multiple error term" which was usually used in the medical field to "additive error term". After using different sizes of error terms to generate pseudo data by computer simulation, we fit the parameters and estimate the values of the function to the crude data we've created with the four fitting methods mentioned above. Comparing the fitting result of the simulation data and the real data, we think the most robust fitting method is " Whittaker Graduation". The real data we have fitted in this essay may contain a greater error term, it would make " Nonlinear Function Parametric Graduation" get inadequate fitting values.
| Identifer | oai:union.ndltd.org:CHENGCHI/A2002002155 |
| Creators | 簡仲徽 |
| Publisher | 國立政治大學 |
| Source Sets | National Chengchi University Libraries |
| Language | 中文 |
| Detected Language | English |
| Type | text |
| Rights | Copyright © nccu library on behalf of the copyright holders |
Page generated in 0.0027 seconds