肺癌脑转移瘤DSC-PWI:ASL最佳标记延迟时间分析

DSC-PWI of brain metastases from lung cancer:analysis of the optimal post labeling delay time for ASL

目的:通过与动态磁敏感对比增强灌注成像(DSC-PWI)进行对比,探讨动脉自旋标记灌注成像(ASL-PWI)在评估肺癌脑转移时的最佳标记后延迟时间(PLD)。方法:前瞻性将在本院确诊为肺癌脑转移的33例患者纳入本研究。其中,肺腺癌18例,肺鳞癌15例。所有患者行DSC-PWI和不同PLD(1.0、1.5、2.0和2.5 s)3D-ASL-PWI扫描。由两位医师对4组(不同PLD)ASL-PWI伪彩图进行图像质量评分,并采用Kappa检验进行一致性评估。基于DSC-PWI的诊断结果,比较不同PLD的ASL-PWI对脑转移瘤的检出效能。测量ASL-PWI和DSC-PWI图像上肿瘤内异常灌注区和对侧镜像区的灌注参数值,并对脑血流量(CBF)和脑血容量(CBV)进行标准化,获得不同PLD ASL-PWI的rCBF及DSC-PWI的rCBF、rCBV、平均通过时间(MTT)和达峰时间(TTP)。不同PLD ASL-PWI的图像质量主观评分、肿瘤显示情况评级和rCBF值的比较采用Friedman秩和检验。ASL-rCBF与DSC-rCBF的比较采用Wilcoxon检验。采用Spearman检验分析ASL-PWI参数(rCBF)与DSC-PWI参数(rCBF、rCBV、MTT、TTP)的相关性。结果:不同PLD的ASL-PWI图像质量主观评分的差异有统计学意义(P<0.05),1.5 s PLD时图像质量主观评分最高,中位数为4.0(4.0,4.0)分。在1.5 s PLD时,ASL-PWI对肺腺癌和肺鳞癌脑转移瘤的显示能力评级最高,中位数均为2.0(1.0,2.0)级;检出率分别为100%和93.33%。随着PLD的增加,两种病理类型脑转移瘤的rCBF均逐渐增加(P<0.05);在PLD为1.5和2.0 s时,两者的ASL-rCBF与DSC-rCBF之间的差异均无统计学意义(P>0.05)。不同PLD时肺腺癌脑转移瘤的ASL-rCBF与DSC-rCBF和DSC-rCBV均具有相关性(P<0.05),以PLD为1.5 s时的相关性最高(r=0.910、0.794)。肺鳞癌脑转移瘤的ASL-rCBF在不同PLD时与DSC-rCBF均具有相关性(P<0.05),以PLD为1.5 s时的相关性最大(r=0.925),其与rCBV、MTT及TTP均无显著相关性(P>0.05)。结论:PLD为1.5 s时,ASL-PWI对肺癌(腺癌和鳞癌)脑转移的诊断效能最高,获得的rCBF值与DSC-PWI结果相近。

Objective:To investigate the optimal post-label delay time(PLD)in arterial spin labeling perfusion weighted imaging(ASL-PWI)for assessing brain metastases from lung cancer by comparison with dynamic susceptibility contrast-enhanced perfusion-weighted imaging(DSC-PWI).Methods:33 patients with confirmed brain metastases from lung cancer(18 cases with adenocarcinomas and 15 cases with squamous cell)were prospectively collected in this study.All patients underwent 3DASL-PWI with different PLDs(1.0,1.5,2.0 and 2.5s)and DSC-PWI scans.The image quality of the ASL-PWI pseudo-color images of the four groups(different PLDs)was scored by two physicians.The inter-reader consistency was assessed using Kappa test.Based on the diagnostic results of DSC-PWI,the efficacy of ASL-PWI with different PLDs in detecting brain metastases was compared.On ASL-PWI and DSC-PWI images,the values of perfusion parameters in the abnormal perfusion region within the tumor and its mirrored area on the opposite side were measured,and the values of cerebral blood flow(CBF)and cerebral blood volume(CBV)were normalized.Finally,the quantitative parameters from DSC-PWI including ASL-rCBF at different PLDs as well as rCBF,rCBV,mean transit time(MTT)and time to peak(TTP)were obtained for statistical analysis.Friedman rank sum test was performed to compare the subjective scores of images quality,tumor clearness rates and rCBF va-lues among ASL-PWI images with different PLDs.The Wilcoxon test was used to compare rCBF va-lues between ASL-PWI and DSC-PWI.Spearman non-parametric correlation test was applied to analyze the correlation between ASL-PWI parameters(rCBF)and DSC-PWI parameters(rCBF,rCBV,MTT and TTP).Results:Using different PLDs,statistically significant differences were found in the subjective scores of ASL-PWI image quality(P<0.05),and the highest median subjective score of 4.0(4.0,4.0)was found on 1.5s PLD perfusion pseudo-color mapping.At 1.5s PLD,ASL-PWI had the highest capability grade with median of 2.0(1.0,2.0)to depict brain metastases from lung adenocarcinoma and squamous cell carcinoma,with detection rates of 100%and 93.3%,respectively.The rCBF values gra-dually increased with the increase of PLD in both pathological types of brain metastases(P<0.05),and no statistically significant difference in rCBF values was found between DSC-PWI and ASL-PWI with 1.5 and 2.0s PLD(both P>0.05).The ASL-rCBF values of brain metastases from lung adenocarcinoma at different PLDs all showed significant correlation with DSC-rCBF and DSC-rCBV va-lues(all P>0.05),with the highest correlation at 1.5s PLD(r=0.910 and 0.794);but they had no significant correlation with DSC-MTT and DSC-TTP(all P>0.05).The ASL-rCBF values of brain metastases from lung squamous cell carcinoma at different PLDs were all correlated with DSC-rCBF values(all P<0.05),with the highest correlation(r=0.925)at 1.5s PLD;but they had no significant correlation with DSC-rCBV,DCS-MTT and DSC-TTP(all P>0.05).Conclusion:When PLD is 1.5s,the diagnostic efficacy of 3D-ASL-PWI for brain metastases from lung cancer,including adenocarcinoma and squamous cell carcinoma,is the highest,and the obtained rCBF value is similar to that of DSC-PWI.