能谱CT多参数成像评估胆结石成分的应用价值

Predictive value of multiparameter spectral CT imaging for characterization of gallstone composition

摘要:

目的 探究能谱CT多参数成像评估胆固醇结石和非胆固醇结石的应用价值。方法 收集125枚胆结石置入猪肝模型中行CT能谱模式扫描，并重建普通螺旋CT图像，测量所有胆结石单能量40 keV、100 keV时的CT值（HU_{40 keV}、HU_{100 keV}）、有效原子序数（Eff-Z）和普通螺旋CT值（HU_{120 kVp like}），并计算40～100 keV区间能谱衰减斜率（K），根据红外光谱分析结果分为胆固醇结石组56枚和非胆固醇结石组69枚。采用秩和检验比较两组各参数差异，利用多因素Logistic回归分析判断胆结石成分的独立影响参数，绘制受试者工作特征（ROC）曲线，分析评估影响效能及截断值。招募胆结石患者80例，术前行CT能谱模式扫描并重建普通螺旋CT图像，分别预测术前胆结石成分，术后取出86枚胆结石行红外光谱分析，分析各参数预测结果的准确性。结果 体外非胆固醇结石组HU_{40 keV}、HU_{100 keV}、Eff-Z、K值及HU_{120 kVp like}与胆固醇结石组比较，差异有统计学意义（P <0.05），非胆固醇结石组高于胆固醇结石组。多因素Logistic回归分析结果显示仅Eff-Z［R=12.57（95% CI：5.38，29.35）］是胆固醇和非胆固醇结石的影响因素，其ROC曲线下面积为0.962（95% CI：0.928，0.997），对应截断值为7.27。体内验证结果显示，以术后红外光谱分析为参照，能谱CT预测胆结石成分的总准确率为91.86%（95% CI：0.831，0.967），而普通螺旋CT预测的总准确率仅为77.9%（95% CI：0.690，0.872），能谱CT与红外光谱分析结果具有较高的一致性（κ =0.832，P <0.05）。而普通螺旋CT值预测胆结石成分结果与红外光谱分析结果一致性一般（κ =0.561，P <0.05）。结论 能谱CT多参数成像可较准确地评估胆结石成分，尤其以Eff-Z参考价值为佳，优于普通螺旋CT扫描。

Abstract:

Objective To investigate the application value of multiparameter Spectral CT for evaluating cholesterol stones and non-cholesterol stones.Methods A total of 125 gallstones were collected and placed in pig liver underwent CT scans with CSI mode，and the images of general spiral CT were reconstructed. The CT value of single energy (40 KeV and 100 keV)（HU40 keV、HU100 keV, effective atomic number (Eff-Z)，the slope of spectral HU curve (κ), and the CT value of general spiral （HU120 kvp like）for each gallstone were obtained. Gallstones were identified according to the Infrared spectroscopy analysis，and were divided into cholesterol groups (n = 56) and non-cholesterol stone groups (n = 69). The above parameters between the two groups were compared using rank sum test. Multivariate Logistic regression analysis was accomplished to obtain the independent influence parameters, ROC curve analysis was performed regarding the influence efficiency, and cut-off value were calculated. 80 patients with gallstones underwent preoperative spectral CT scanning and the images of general spiral CT were reconstructed. The composition of preoperative gallstones were predicted, respectively. A total of 86 gallstones was obtained, in order to analyze the accuracy of spectral CT images and general spiral CT images，with the results of Infrared spectroscopy as the reference standard.Results The HU40 keV, HU100 keV, Eff-Z, κ value, and HU120 kvp like of the non-cholesterol gallstones group were significantly higher than those of the cholesterol gallstones group (P < 0.05). Multivariate logistic regression analysis showed that only Eff-Z [R = 12.57 （95% CI: 5.38, 29.35)] level was an influential factor for cholesterol and non-cholesterol gallstone, of which AUC was 0.962（95% CI: 0.928, 0.997）and the cut-off values were 7.27. Compared with the results of postoperative Infrared spectroscopy, the total accuracy rates of spectral CT in the diagnosis of gallstone composition was 91.86% (79/86) （95% CI: 0.831, 0.967）. However, the total accuracy rates of general spiral CT was 77.9%（67/86）（95% CI: 0.690, 0.872）. The diagnosis results of gallstones composition by spectral CT were well consistent with the Infrared spectroscopy (κ = 0.832, P < 0.05). while the results of the general spiral CT were generally consistent (κ = 0.561, P < 0.05).Conclusion Spectral CT multiparameter imaging can accurately predict gallstone composition，and especially the Eff-Z has optimal reference significance，which is superior to general spiral CT scan.