CT增强模拟常规灌注成像评价兔VX2肝癌的可行性研究

摘要

Objective To investigate the feasibility of simulating real CT perfusion imaging with 5-phase CT enhancement scan in rabbits with VX2 hepatocellular carcinoma. Methods Liver perfusion was performed on 38 rabbit VX2 liver cancer models using 320-row volume CT, with raw data from the perfusion imaging that was extracted including unenhanced, early artery phase, artery phase, late artery phase, portal phase. Three perfusion parameters including artery flow (AF), portal flow (PF) and hepatic perfusion index (PI), were obtained separately by post-processing software. The radiation doses were recorded separately. All the parameters were obtained by two independent observers and the observer consistency was evaluated. The consistency of the parameters of perfusion in normal liver parenchyma and tumor virable area at 5-phase CT enhancement and real CT perfusion was compared. The differences of perfusion parameters between normal liver parenchyma and tumor virable area were compared on 5-phase CT enhancement and real CT perfusion. We evaluated the correlation between perfusion parameters and MVD in normal 25 and 5 phases of enhanced CT. Results 1) For normal liver parenchyma and tumor active tissue, the perfusion parameters of phase 5 enhanced CT and 25 conventional CT showed good consistency, for the normal liver parenchyma, the ICC was AF (0.7798), PF (0.5795), PI (0.8371), while, for the tumor virable area, the ICC was AF (0.5346), PF (0.8475), PI (0.7275); 2) There was significant difference between the tumor virable area and the normal liver parenchyma perfusion parameters in the 5-phase enhanced perfusion and dynamic enhancement perfusion (P＜0.05); 3) The correlation between MVD and dynamic perfusion CT perfusion index was AF (0.4969), PF (-0.7892), PI (0.8946), while for 5-phase, that AF (0.4058), PF (-0.7143), PI (0.9690); 4) The radiation dose of enhanced CT perfusion was significantly lower than that of dynamic CT. The difference was statistically significant (P ＜0.05). Conclusion The evaluation results of phase 5 enhanced CT perfusion in normal liver parenchyma and tumor virable area are in good agreement with that of phase 25 conventional CT perfusion, suggesting that phase 5 CT perfusion can roughly simulate 25 conventional CT perfusion and significantly reduce the radiation dose. The results of CT perfusion in phase 5 are consistent with that of MVD.%目的 使用VX2肝癌兔CT增强5期扫描, 探讨模拟常规25期灌注成像的可行性.方法 采用320排容积CT对38只兔VX2肝癌模型进行肝脏灌注扫描, 从常规25期图像中依据时间密度曲线(TDC)选取5期增强图像(平扫、动脉早期、动脉期、动脉晚期、门静脉期及延迟期), 并利用后处理软件分别获得其灌注参数的伪彩图, 包括动脉血流量(AF)、门静脉血流量(PF)、肝脏灌注分数(PI), 并分别记录其辐射剂量.比较正常肝实质及肿瘤活性区5期增强CT与常规25期灌注各参数之间的一致性;比较5期增强CT及常规25期灌注图像上正常肝实质、肿瘤活性病灶间灌注参数的差异;评价常规25期灌注和5期增强CT的灌注参数分别与肿瘤微血管密度(MVD)的相关性.结果 1)对于正常肝实质及肿瘤活性组织, 5期增强CT与常规25期CT灌注各参数之间均有较好的一致性(正常肝实质AF、PF、PI的组内相关系数(ICC)依次为0.7798、0.5795、0.8371, 肿瘤活性区AF、PF、PI的ICC值依次为0.5346、0.8475、0.7275);2)常规25期灌注及5期增强的正常肝实质与肿瘤活性区各灌注参数之间的差异均有统计学意义(P＜0.05);3)MVD与25期灌注参数的相关系数(r)依次为AF(0.4969)、PF(-0.7890)、PI(0.8946);MVD与5期增强灌注参数的r值依次为AF(0.4058)、PF(-0.7143)、PI(0.9690);4)5期增强CT辐射剂量明显低于25期CT灌注, 其差异有统计学意义(P＜0.05).结论 5期增强CT对正常肝实质及肿瘤活性区灌注评估结果与常规25期CT灌注有较好的一致性, 提示5期CT灌注可大致模拟常规25期CT灌注, 同时显著降低辐射剂量.5期CT灌注结果与MVD有较好的一致性.