多模式影像對位與融合技術之研究-以金花石蒜鱗莖影像為例

A Study of Multimodal Image Registration and Fusion:Images of Lycoris aurea Herb. Bulbs

吳東璋(Tung-Chang Wu)

指導教授 ： 林達德

國立臺灣大學/生物資源暨農學院/生物產業機電工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.02322

摘要

金花石蒜為台灣的原生球根花卉，是台灣主要的出口花卉之一。為了解其鱗莖生長過程與性質常需透過破壞性實驗進行研究，本研究將兩種不同模式之非破壞性影像，核磁共振影像與電腦斷層掃描影像整合，開發一套適用於金花石蒜鱗莖之影像對位與融合演算法，達到連續觀察同一鱗莖成長過程之目的。對於核磁共振影像，使用7T Bruker Biospec 70/30 USR小系統核磁共振儀，以 MSME (Multi-slice-multi-echo)掃描序列，利用不同的重複時間與迴訊時間掃描參數，尋找最佳成像參數。而電腦斷層掃描儀則使用GE eXplore Vista PET/CT，以不同的電壓、電流與發射次數，尋找最佳金花石蒜鱗莖組織對比影像。於影像對位與融合演算法中，將電腦斷層影像與核磁共振影像分別視為參考影像與測試影像，在影像前處理時，利用Hotelling轉換重新定位兩影像，再使用剛性轉換函式，依面積樣板的匹配指標，輸出最佳的轉換函數參數，將兩異質影像融合為棋盤式影像，其中匹配指標達87.4%。在41張棋盤式融合影像中，有36張邊緣完全接合。而對於金花石蒜鱗莖內部形態，在五月休眠期時，即可明顯區分葉芽或花芽，並發現當溫度由28℃下降至23℃左右，花芽會快速成長並抽苔。本研究中並利用核磁共振影像當中的T2值與電腦斷層掃描的CT值探討金花石蒜鱗莖內部水分變化情形，實驗結果顯示金花石蒜鱗莖乾燥過程中，T2值與CT值皆會下降。

關鍵字

影像對位 ； 影像融合 ； 核磁共振影像 ； 電腦斷層掃描 ； 植物形態

並列摘要

Lycoris aurea Herb., one of Taiwan’s major export flowers, is a flower bulb native to Taiwan. The invasive experiments usually used to understand the growth progress and properties of the bulbs. In this study, the images from the two non-invasive techniques, X-ray computed tomography (CT) and magnetic resonance imaging (MRI) had been integrated to develop an image registration and fusion algorithm, which is applied to observe the continuous changes of the same Lycoris aurea Herb. bulb. In MRI experiments, parameters such as repetition time (TR), echo time (TE) were adjusted by using a standard MSME (Multi-slice-multi-echo) spin-echo sequence in the 7T Bruker Biospec 70/30 to acquire high quality MR images with high contrast. On the other hand, the CT scanner was performed in GE eXplore Vista PET/CT, and parameters such as voltages, current, and shots of the X-ray source were adjusted to obtain the CT images with good tissue contrast of Lycoris aurea Herb. bulb. In image registration and fusion algorithm, CT images and MR images was regarded as reference image and test image, respectively. In image preprocessing, Hotelling transform was employed to realign the two images, and then rigid transformation was used to output the best parameters of transform function according to the matching index of area template. Finally, the two images were fused to the checkerboard rendered image. The matching index up to 87.4% and 36 images were fully matched in 41 block fusion images. For the morphological structure of Lycoris aurea Herb. bulbs, the difference between the flower and leaves buds were classified obviously in dormancy status in May. In addition, the flower buds grew quickly when the temperature decrease from 28℃ to 23℃. The moisture content change of interior Lycoris aurea Herb. bulb was evaluated by the T2 value and CT number. The results showed that both T2 value and CT number decreased during the drying process of Lycoris aurea Herb. bulb.

並列關鍵字

image registration ； image fusion ； magnetic resonance imaging ； computed tomography ； plant morphology

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