256层螺旋CT结直肠癌灌注成像扫描时间对灌注参数的影响

The Influence of Scanning Time of 256-Slice Spiral CT Perfusion Imaging for Colorectal Cancer on the Perfusion Parameters

目的评估256层螺旋CT结直肠癌灌注扫描时间变化对灌注参数的影响,以获取基于首过效应阶段灌注扫描序列的最佳灌注扫描时间。方法搜集术前经纤维结肠镜检查并由术后病理证实结直肠腺癌病例29例,进行256层螺旋CT全肿瘤灌注检查。每位患者总灌注扫描时间为60.8 s,通过后处理软件由两位放射科医师分别在60.8 s、57 s、53.2 s、49.4 s、45.6 s、41.8 s、38 s测量肿瘤最大层面灌注参数(BF,BV,TTP,PEI)值,观察其变化。将扫描时间60.8 s所测灌注参数分别与扫描时间(57 s、53.2 s、49.4 s、45.6 s、41.8 s、38 s)灌注参数进行配对样本t检验。对不同医师两次分析结果运用Bland-Altman分析进行一致性分析。P<0.05为差异具有统计学意义。结果灌注参数(BF,BV,TTP,PEI)值受到总扫描时间影响。扫描时间为60.8 s时,灌注参数BF、BV、TTP、PEI值分别为(34.12±17.83)ml·min-1·100g-1、(14.76±4.99)ml/100g、(18.92±10.22)s、(36.35±14.64)HU。总扫描时间减至41.8 s,其BF值为(40.35±28.52)ml·min-1·100g-1,与60.8 s所测BF值之间差异有统计学意义(P=0.049);总扫描时间减至45.6 s,其TTP值、PEI值分别为(15.23±7.79)s、(33.68±13.72)HU,与60.8 s所测值之间差异有统计学意义(P=0.024;P=0.022)。随着扫描时间缩短,BV值逐渐减小,与60.8s所测BV值之间差异均存在统计学意义(P<0.05)。结论基于首过效应法256层螺旋CT结直肠癌灌注成像总扫描时间对灌注参数(BF,BV,TTP,PEI)值有明显影响。总扫描时间46 s左右能够保证BF、TTP及PEI测定的准确性,而BV值的准确测定可能需延长扫描时间。

Objective To assess the influence of scanning time of 256-slice spiral CT perfusion imaging for colorectal cancer on the perfusion parameters, including blood flow （BF）, blood volume （BV）, time to peak （TIP） and peak enhancement intensity （ PEI）, in patients with colorectal cancer in order to find out the optimal perfusion scan time. Methods The whole tumor perfusion CT scan was performed in 29 patients with pathologically confirmed colorectal adenocarcinoma. The patients included 20 males and 9 females, aged 56.89 ±14.65 years. The total perfusion scan time for each patient was 60.8s. Using post-processing software the maximum slice of tumor perfusion parameters （BF, BV, TFP and PEI） values were separately measured by two radiologists at the following points of time： 60.8s, 57.0s, 53.2s, 49.4s, 45.6s, 41.8s and 38.0s. The perfusion parameters obtained at different scan time were compared with the parameters at 60.8s using paired samples t-test. The measurement reproducibility by two observers was analyzed using Bland-Ahman analysis. Statistical significance was set at P 〈 0.05. Results Perfusion parameters （ BF, BV, TTP and PEI） values were influenced by the total scan time. When scan time was 60.8 s, the BF, BV, TIP and PEI values were （34.12 ±17.83） mlmin^-1·100g^-1, （14.76 ±4.99） ml/100g, （18.92 ±10.22） s and （36.35 ±14.64） HU respectively. When the scan time was reduced to 41.8 s, the BF value was （40.35 ＋ 28.52） ml min^-1·100g^-1. The difference was statistically significant when compared with the value obtained at 60.8s （P = 0.049）. When the total scan time was reduced to 45.6s, The TIP value and PEI values were （ 15.23 ±7.79） s and （33.68 ±13.72） HU respectively. The differences were statistically significant when compared with the values obtained at 60.8s （P = 0. 024 and P = 0.022 respectively）. With the reduction of the scanning time, BV value decreased gradually, and the BV value was statistically significant different with the BV value determined at 60.8s （P 〈 0.05）. Conclusion Based on the first-pass phase effect method, the total scanning time of 256-slice spiral CT perfusion imaging for colorectal cancer has significant effect on the perfusion parameters （BF, BV, TIP and PEI） values. When the total scan time is set at about 46s, the accuracy of BF, TIP and PEI determination can be ensured; while the accurate determination of BV value may need a longer scanning time.