Diagnosis of Pulmonary Embolism by Computed Tomographic Pulmonary Angiography With and Without Optimal Contrast Enhancement: a Prospective Single Centre Audit
S Lloyd, A Sahu, R Riordan
Hong Kong J Radiol 2012;15:162-9
Objective: We aimed to establish whether there was a correlation between the diagnostic efficacy of computed tomographic pulmonary angiography for pulmonary embolism and the degree of pulmonary arterial enhancement measured objectively by main pulmonary artery attenuation level. Based on previous literature, we also evaluated the utility of setting a main pulmonary artery enhancement level of 211 Hounsfield Units (HU) as a minimum level for enhancement to optimise the number of determinate scans.
Methods:We performed an audit of the main pulmonary artery attenuation levels and reported patient outcomes of 416 computed tomographic pulmonary angiograms performed within our institution between January and April 2010. We then implemented a series of changes to our computed tomographic pulmonary angiography protocol aimed at optimising main pulmonary artery enhancement, before conducting a prospective re-audit of a further 100 computed tomographic pulmonary angiograms. Statistical analysis was performed to identify any correlation between enhancement and reported outcomes, using a main pulmonary artery attenuation level of 211 HU to denote adequate enhancement.
Results:Protocol changes resulted in an increase in main pulmonary artery enhancement and a corresponding decrease in the percentage of indeterminate examinations. There were significant differences between both the median main pulmonary artery attenuation levels of determinate and indeterminate scans (p < 0.001) and the percentages of determinate and indeterminate scans with main pulmonary artery attenuation levels of less than 211 HU (p < 0.001).
Conclusion: A significant correlation exists between pulmonary arterial enhancement level and whether or not computed tomographic pulmonary angiography is determinate for pulmonary embolism. Our audit validates the use of 211 HU as a minimum level of enhancement to optimise the number of determinate scans.
中文摘要
在有或無最佳對比度增強的情況下電腦斷層肺血管造影在診斷肺栓塞的 效果：一項前瞻性單中心研究
S Lloyd, A Sahu, R Riordan
目的：探討電腦斷層肺血管造影對肺栓塞的診斷效果是否與肺動脈增強程度有關聯。根據過往文 獻，嘗試把主肺動脈最低增強水平設定為211亨氏單位（HU）來評估是否能優化「確定診斷掃描」 的數量。
方法：本研究回顧2010年1月至4月期間在本院進行的主肺動脈增强CT。研究期間共有416個電腦斷 層肺血管造影結果。為優化主肺動脈增強掃描，我們把電腦斷層肺血管造影模式加以改良，然後重 新進行一項前瞻性研究，檢視了100份電腦斷層肺血管造影。為確保主肺動脈有足夠的增強掃描，我 們把最低水平設為211 HU，並進行統計分析來探討任何增強掃描與檢視結果之間的關係。
結果：掃描模式的改變使主肺動脈增強增加，同時令「不確定診斷掃描」的百分比相應減少。「確 定診斷掃描」和「不確定診斷掃描」中的主肺動脈增强CT值的中位數有顯著差異（p < 0.001），使 用主肺動脈增强CT值為211 HU以下的「確定診斷掃描」和「不確定診斷掃描」的百分比亦有顯著差 異（p < 0.001）。
結論：肺動脈增強水平和電腦斷層肺血管造影用作診斷或排除肺栓塞有著明顯關係。本研究亦證明 211 HU可以作為增強的最低水平，從而優化「確定診斷掃描」的數量。