Cerebral Perfusion Computed Tomography with a New Scanning Protocol and Reduced Scanning Time: Retrospective Review
KC Chan, JM Abrigo, TCY Cheung, SW Cheung, DYW Siu
Hong Kong J Radiol 2013;16:203-8
DOI: 10.12809/hkjr1312154
Objective: To retrospectively analyse the quantitative change in cerebral blood flow, cerebral blood volume, and mean transit time after adopting a new protocol for perfusion computed tomography (PCT) where the delay time for scanning was changed from 5 to 8 seconds and acquisition time decreased from 50 to 42 seconds.
Methods: All elective cerebral PCTs performed from June to October 2009 were retrieved. The original dataset and extracted dataset (excluding the first 3 seconds and last 5 seconds of the original dataset which corresponded to the new protocol) were pair-wise processed in the same workstation. This entailed using the same arterial input and venous output functions; 12 identical regions of interest were applied. Perfusion parameter values were compared using the Wilcoxon rank signed test. Significance was declared at an α ≤ 0.05.
Results: A total of 45 PCTs with and without acetazolamide challenge were included, yielding 540 regions of interest. The mean percentage differences of cerebral blood flow, cerebral blood volume, and mean transit time between the two datasets were significant (p < 0.001) but small (5.9%, 5.0% and 4.2%, respectively). In the extracted datasets, the absolute values remained within a 15.0% difference in 97.0% of the cerebral blood flows, 99.8% of the cerebral blood volumes, and 99.6% of the mean transit times. With the new protocol, on average a 15.9% reduction in radiation dosage was achieved.
Conclusion: By adopting our new scanning protocol for cerebral PCT, a significant reduction in radiation dosage was achieved, while the changes in cerebral blood flow, cerebral blood volume, and mean transit time values were considered acceptable.
中文摘要
應用新掃描方案及掃描時間縮短的CT腦灌注成像：回顧性研究
陳嘉智、JM Abrigo、張智欣、 張兆偉、蕭容媛
目的：在新的電腦斷層（CT）灌注成像方案中，掃描延遲時間由5秒增至8秒，而採集數據時間則從50秒減至42秒。本研究回顧分析採用這種新方案後，在腦血流量、腦血容量和對比劑平均通過時間方面的變化。
方法：分析2009年6月至10月期間所有CT腦灌注成像的紀錄。在同一工作站配對處理原始數據和提取數據（捨棄前3秒和最後5秒的原始數據使之和新掃描方案一致）。處理過程需要使用相同的動脈輸入和靜脈輸出功能；並採用12個相同的感興趣區。應用Wilcoxon秩和檢驗比較灌注參數值。α ≤ 0.05表明差異有顯著性。
結果：共有45個CT灌注成像，其中部份有乙酰唑胺（acetazolamide）負荷，產生540個感興趣區。兩組數據在腦血流量、腦血容量和對比劑平均通過時間的平均百分比差異具顯著性（p < 0.001），但差異偏小（分別為5.9%、5.0%和4.2%）。提取數據中，在97.0%的腦血流量，99.8%的腦血容量和99.6%的平均通過時間的絕對值仍在15.0%差異範圍內。新方案令輻射劑量平均減少了15.9%。
結論：通過採用新的CT腦灌注成像方案，輻射劑量顯著減少，而腦血流量、腦血容量和對比劑平均通過時間值的變化仍可接受。