体外区分泌尿系结石成分:对比观察CT能谱扫描与常规扫描

Composition judgment of in vitro upper urinary calculi: Comparison of gemstone spectral CT and conventional polychromatic X-ray imaging

目的观察常规120kVp混合能量图与能谱CT单能量图区分体外不同成分泌尿系结石的价值。方法将已知单一成分的84枚泌尿系结石(尿酸类结石11枚,鸟粪石结石17枚,胱氨酸结石10枚,磷酸钙结石31枚,草酸钙结石15枚)分别置于猪肾中,采用宝石CT行能谱成像(GSI)扫描及常规120kVp扫描,测量并计算GSI图像的单能量(40～140keV,间隔10keV)CT值、能谱衰减曲线的斜率及120kVp混合能量CT值,并采用方差分析比较不同成分结石CT值的差异。结果在120kVp混合能量图像上,5种不同成分结石的CT值差异有统计学意义(P<0.001)。5种结石单能谱CT值差异均有统计学意义(P<0.001)。两两比较,上述5种结石在50keV时CT值差异均有统计学意义(P<0.05)。5种结石能谱衰减曲线斜率间差异均有统计学意义(P<0.001)。两两比较,5种结石间斜率差异均有统计学意义(P<0.05)。结论与CT常规120kVp混合能量相比,单能量CT值可以有效区分上述5类结石。能谱CT单能量50keV为分析体外泌尿系结石成份的最佳参数。

Objective To assess the value of spectral CT （Discovery CT750 HD） and conventional polychromatic X ray imaging （120 kVp） for composition judgment of in vitro upper urinary calculi. Methods Eighty four urinary calculi, including uric acid stones （UA, n= 11）, struvite stones （STR, n= 17）, cystine stones （CYS, n= 10）, calcium phosphate （CAP, n=31） and calcium oxalate （COX, n= 15） were inserted in excised pig kidneys which underwent gemstone spectral imaging （GSI, 40-140 keV, interval of 10 keV） and conventional 120 kVp scan. CT values of GSI and conventional 120 kVp, slop of energy spectrum attenuation curve were examined and calculated. ANOVA analysis was used to compare the CT values of different stones. Results CT values of 5 different components stones were significantly different in 120 kVp （P〈0. 001）, so as in single energy spectrum CT （P〈0. 001）, while CT values of different component stones in 50 keV were significantly different between each other （P〈0.05）. The spectrum attenuation curve slopes were significantly different （P〈0. 001）, while binary comparison showed significant differences among 5 types of stones （P〈0.05）. Conclusion In GSI of urinary calculi, compared with polychromatic images （120 kVp）, the optimal monochromatic levels determined at 50 keV can judge the component of in intro urinary calculi better.