Quantitative susceptibility mapping (QSM) 在監測組織的磁特性上已經是一個有用的工具。傳統的腦部QSM需要涵蓋全腦以及有足夠的解析度，因此會需要較長的掃描時間以及導致在實際臨床應用上的限制。
在我們的研究中，Generalized Autocalibraing Partially Parallel Acquisition (GRAPPA) 和部分體積涵蓋範圍來實現影像擷取時間的減少。另外，部分腦體積涵蓋範圍包括二分之一涵蓋範圍以及四分之一涵蓋範圍。Projection onto Dipole Field (PDF) 方法是根據ROI外部的背景偶極場和Region of interest (ROI) 內的局部偶極場的內積幾乎為零，除了ROI邊界附近的局部偶極場。因此，ROI邊界附近的估算是不准確的。本研究透過數值模擬以及人類受試者資料模擬來探討在切面方向的錯誤邊界範圍以及在特定ROI上的準確性。為了評估GRAPPA和部分腦涵蓋範圍的品質，進行人類受試者實驗並分析特定ROI的重建的磁化率 (susceptibility)。因此，應用在QSM上，二分之一腦涵蓋範圍，GRAPPA以及它們的組合在縮短掃描時間上是合適的選擇。

Quantitative susceptibility mapping has been a useful tool to monitor magnetic properties of the tissues. Conventional cerebral QSM requires 3D whole brain coverage and spatial resolution, leading long scan time and also limiting its application in clinical practice.
In this study, Generalized Autocalibraing Partially Parallel Acquisition (GRAPPA) and partial volumetric coverage are used to implement reduction of acquisition time. In addition, partial brain coverages are including half and quarter coverages here. The Projection onto Dipole Field (PDF) method processes due to the basis that the inner product of the field of a background dipole outside the ROI and the field of a local dipole inside the ROI is almost zero except for the local dipole near the ROI boundary. Therefore, the estimation near the ROI boundary is inaccurate. Numerical simulation and human subject simulation were performed to investigate the error bounday along slices and also the accuracy of specific ROIs. To assess the quality of GRAPPA and partial brain coverage, human subject experiment was performed and the reconstructed susceptibility values of specific ROIs were analyzed. Consequently, half brain coverage, GRAPPA and also their combination in QSM are suitable options to shorten scanning time.

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