探究靶重建结合ASIR-V算法对胃部血管及肿瘤供血动脉显示的应用价值

To Explore the Application Value of Targeted Reconstruction Combined with High ASIR-V Algorithm Strength in Gastric Vascular and the Blood Supply of Tumor Display

目的探究能谱CT靶重建(小DFOV)结合自适应统计迭代重建算法(ASIR-V)对胃部血管及肿瘤供血动脉显示的应用价值。方法前瞻性搜集行腹部CTA检查的胃部肿瘤患者40例,采用GSI模式扫描,扫描完成后,对原始数据进行两组重建,A组为常规组,重建70 keV结合50%ASIR-V轴位图像,DFOV包含四周皮缘;B组为实验组,采用70 keV结合50%~100%ASIR-V(间隔10%)靶重建,DFOV的大小涵盖整个胃部血管及肿瘤供血动脉,获得B1~B66个亚组。记录A、B两组的DFOV大小,在轴位图像上测量胃左动脉起始部的腹主动脉、腹腔干、脾动脉、肝动脉及同层面腹壁皮下脂肪组织的CT值和SD值,计算上述血管的信噪比(SNR)、对比噪声比(CNR)。由两名观察者采用五分法评估各组轴位、VR和MIP的图像质量、胃部血管及肿瘤供血动脉的显示情况,并行Kappa一致性检验。结果A、B组的DFOV大小分别为(44.59±3.57)cm、(22.04±1.86)cm。A、B两组的腹主动脉、腹腔干、脾动脉、肝动脉的CT值差异无统计学意义(P>0.05),B1~B6组随着ASIR-V权重的增加,图像SD值逐渐下降(P<0.05),SNR、CNR逐渐升高(P<0.05)。与A组相比,B4组除腹腔干的SD值、肝动脉的CNR值外,其余血管SD值、SNR、CNR和背景噪声均无统计学差异(P>0.05);两名观察者主观评价一致性较好(Kappa值0.869~0.905,P<0.05),B1~B6组图像质量的主观评分随着ASIR-V权重的增加呈现先高后低的趋势,B4组得分最高(P<0.05),其中,观察者1对B4组二维图像评分与A组差异无统计学意义;B1~B6组在三维图像评分中,B1组与A组差异无统计学意义(P>0.05),余下各组得分均高于A组(P<0.05),B4组得分最高(4.48±0.51);40例胃部肿瘤中有32例见胃动脉系统参与供血,B4组的胃左动脉、胃右动脉、胃网膜左动脉、胃网膜右动脉、胃后动脉、胃短动脉及肿瘤供血动脉的清晰显示率分别为97.5%、65.0%、77.5%、100%、5.0%、5.0%、62.5%,均优于A组。结论采用靶重建结合80%ASIR-V能够显著提高胃部血管及肿瘤供血动脉分支的显示,为临床诊疗提供更准确的影像信息。

Objective To explore the application value of using targeted display field of view(DFOV)in conjunction with the increased adaptive statistical iterative reconstruction-V(ASIR-V)algorithm strength in dual-energy CT(DECT)for improving image quality and gastric blood vessel and branch display.Methods 40 patients for abdominal DECT angiography were prospectively collected.The 0.625 mm,70 keV monochromatic images were reconstructed using the standard DFOV and 50%ASIR-V(group A)and targeted DFOV with 50%-100%ASIR-V(interval 10%for 6 six subgroups:B1-B6).The size of the targeted reconstruction covered the entire gastric blood vessel and its branches.The CT and SD values of abdominal aorta,Celiac trunk,splenic artery,and hepatic artery in each group were measured.Subcutaneous adipose tissue of the same slice of the abdominal wall was measured as the background.The signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)were calculated.The three-dimensional VR and MIP images were also obtained for qualitative image quality evaluation.Two observers used the five-point method to evaluate the vascular wall edges'display,image quality,and sharpness.Kappa test was used to examine the consistency.Results The sizes of DFOV in groups A and B were(44.59±3.57)cm and(22.04±1.86)cm,respectively.There were no statistically significant differences of CT values at abdominal aorta,abdominal trunk,splenic artery and hepatic artery in groups A and B(P>0.05).With the increase of ASIR-V percentage in group B,SD values decreased gradually(P<0.05),and SNR values and CNR values increased gradually(P<0.05).Except for the SD of abdominal aorta and the CNR of hepatic artery,images in B4 group(80%ASIR-V)had same SD values,SNR,CNR of vessels,and background noise as group A(all P>0.05).The two observers had good consistency in the evaluation of image quality and the display of gastric blood vessels and tumor supplying arteries(Kappa value:0.869-0.905,P<0.05).The subjective scores for displaying gastric blood vessels and their branches in B1-B6 groups increased with the increase of ASIR-V percentage initially then gradually decreased(P<0.05).But B4 provided higher subjective scores for displaying gastric blood vessels and their branches with the highest subjective score at 4.48±0.51.Gastric artery system was involved in blood supply in 32 cases of 40 gastric tumors.The clear display rates of left gastric artery,right gastric artery,left gastric omental artery,right gastric omental artery,posterior gastric artery,short gastric artery and tumor supplying artery in B4 group were 97.5%,65.0%,77.5%,100%,5.0%,5.0%and 62.5%,respectively,which were all better than those in group A.Conclusion Targeted reconstruction combined with 80%percentage of ASIR-V can significantly improve the visualization of gastric blood vessels and their branches,providing more accurate image information for clinical diagnosis and treatment.