能谱CT提高腹部增强效果的可行性

Feasibility of increasing contrast effect of abdomen using gemstone spectral CT

目的探讨能谱CT(GSI)提高腹部增强效果的可行性。方法收集因病情需要先后接受腹部双期增强CT扫描的27例患者,于第1次均采用传统120kV单电压CT进行扫描(对照组),复查时采用GSI扫描(试验组),两次检查对比剂总量均为600mgI/kg体质量。于增强图像上腹主动脉、肝脏、胰腺、肾脏、下腔静脉、门静脉主干选取ROI进行分析,记录GSI图像上各器官相对于120kV单电压扫描的等价CT值时的平均单能量值(等价亚组),以及CT值提高50%(150%亚组)、100%(200%亚组)时的MEI,并记录所对应的噪声值,比较各亚组间单能量值、CT值与噪声值的差异,评估2名医师对MEI各亚组图像质量的主观评分一致性。结果等价亚组能量值(71.92±3.54)keV,图像噪声为(23.07±3.99)HU,与对照组比较,各器官CT值的差异均无统计学意义(P均>0.05);150%亚组能量值(57.39±2.77)keV,图像噪声为(35.30±7.56)HU,较等价亚组增高了53.01%;200%亚组能量值(49.94±2.72)keV,图像噪声为(44.01±8.59)HU,较等价亚组增高了90.77%。与对照组比较,150%亚组、200%亚组间单能量值、CT值与噪声值差异均有统计学意义(P均<0.01)。2名医师对试验组3个亚组的主观评分一致性均很好(P均<0.01)。结论采用GSI的单能量技术于72keV时可以达到常规120kV的腹部增强CT效果,57keV、50keV时增强效果可分别提高50%、100%。

Objective To assess the feasibility of improving the effect of abdominal enhancement with gemstone spectral imaging （GSI）. Methods Totally 27 patients underwent double phase enhanced CT scan were collected. The traditional 120 kV polychromatie X-ray imaging （TPXI, control group） and GSI method was used during the first scan and return visit respectively, and all scans were using 600 mgI/kg of iodine contrast agent. Various organs and vessels including abdominal aorta, liver, pancreas, kidney, inferior vena cava and portal vein of artery phase （AP） and vein phase （VP） were selected as the ROI. All organs, MEI that equal to TPXI image for equivalent subgroup was calculated, and the MEI value （keV）, CT value, noise value were recorded, then finding out the MEI of 150% （150% subgroup） and 200% （200% subgroup） enhancement effect of TPXI were find out respectively. Compare the MEI, CT value, noise value of 3 subgroups were compared. The consistency of diagnoses results between two radiologist was evaluated. Results In equivalent subgroup, the MEI value was （71.92±3. 54）keV, the image noise was （23.07±3. 99）HU, and the CT value of various organs and vessels had no significant difference between the control group and equivalent group （all P〈0.05）. In 150% subgroup, the MEI value was （57. 39±2. 77）keV, while the image noise was （35. 30±7. 56）HU, increased 53.01% compared to equivalent subgroup. In 200% subgroup, the MEI value was （49. 94 ± 2. 72） keV, image noise was （44.01 ± 8. 59） HU, increased 90. 77% compared to equivalent subgroup, there were significant differences in the MEI, CT value, noise value of 3 subgroups compared with control group （all P〈0. 01）. The consistency between two radiologists were very good （all P〈0. 01）. Conclusion The MEI of 72 keV can achieve the enhancement effect of TPXI, and the MEI value of 57, 50 keV can improve 50%, 100% enhancement effect compared to TPXI.