血管空間佔據(Vascular Space Occupancy, VASO) 磁振造影技術可用來定量腦血容量(Cerebral Blood Volume,CBV)。原理主要是利用在生物體內打入具有可以使T1縮短的GD-DTPA 對比劑後，以反轉回復方法(Inversion Recovery)量測血液訊號消失點在注射對比劑前後的訊號變化，將前後影像相減可以得到一張相對腦血容量的影像。進一步的絕對定量，則可以取影像中全血像素的訊號差與以校正。
除了血管空間佔據方法以外，臨床常用的腦血容量測方法還有注射Gd-DTPA對比劑後連續動態掃描的動態磁化率對比(Dynamic Susceptibility Contrast, DSC)技術，並計算出對比劑集中量隨時間改變的曲線，之後再利用加馬回歸曲線(gamma-variate function)去找出對比劑在第一時間通過大腦後的曲線，並積分此曲線即可得到一張相對腦血容量的影像，在動物模型上，則有藉由注射氧化鐵奈米粒子後，量測血液T2*衰減效應而取得相對腦血容量定量的方法。在本研究論文中，我們在大鼠模型上應用並比較這三種方法，未來希望可以結合這三種方法的優點來發展出更理想的腦血容量絕對定量方法。

Using Vascular Space Occupancy (VASO) technique to determine the absolute cerebral blood volume (CBV) was already reported. An inversion recovery sequence with inversion time just on the blood nulling point was employed in this technique. After injecting T1 shortening agent Gd-DTPA, the signal difference can be calculated as a relative CBV value. Furthermore, the signal difference in whole-blood pixels can be utilized as a normalizing factor for absolute CBV quantification.
In addition to the VASO technique, the most popular method in clinical usage is the dynamic susceptibility contrast MRI (DSC-MRI), which can generate a relative CBV map by successively monitoring the signal time course after injecting Gd-DTPA bolus. For researches on animal model, iron oxide nanoparticles can be used as a blood-pool T2* contrast agent, and relative CBV maps can also be estimated by calculating the T2* decay. In this thesis, we implemented these three methods on a normal rat model and made a comparison. In the future, we expect to develop a hybrid method by combining their advantages, and provide an ideal technique for CBV absolute quantification.

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