能谱CT单能量区分体外肾结石成分的初步实验研究

Preliminary Empirical Study on Characterization of Kidney Stone Using Single Energy of Spectral CT

目的采用能谱CT对体外肾石标本进行扫描,探讨能谱CT单能量与CT常规120kVp混合能量对于区分体外不同成份肾结石的价值。方法已知单一成分(尿酸结石8枚,六水磷酸铵镁结石12枚,胱氨酸结石6枚,碳酸磷灰石结石10枚,一水草酸钙结石30枚)的66枚肾结石,分别置于猪肾中,每肾上、下肾盏及肾盂各放2枚结石,并将其浸入水箱中,采用GE宝石CT行GSI(Gemstone Spectral Imaging)扫描及常规120kVp扫描。测量计算GSI图像的(40keV-140keV,间隔5keV)单能量CT值及120kVp混合能量CT值,并采用方差分析比较各组间结石CT值的差异。上述结石分别采用红外光谱分析仪测定其成分。结果经统计学处理,120kVp混合能量CT值差异有统计学意义(F值为52.773,P值=0.000)。组间两两比较,一水草酸钙结石与碳酸磷灰石结石(P=0.831)、尿酸类结石与胱氨酸类结石混合能量CT值(P=0.411)无统计学差异,其余各组结石间120kVp混合能量CT值差异均有统计学意义(P<0.05)。各组结石单能谱(40keV-140keV,间隔5keV)CT值有统计学差异(F值分别为:269.244、201.823、121.190、97.348、88.719、80.076、71.537、63.110、55.064、47.837、41.086、35.104、30.202、26.182、22.528、19.866、17.501、15.585、14.108、12.785、11.830,P值均=0.000)。组间两两比较,上述5组结石在50keV时CT值均有统计学差异(P<0.05);40keV及45keV能区分出尿酸结石与非尿酸结石。结论宝石能谱单能量低keV(40keV-50keV)CT值可以区分出尿酸类结石与非尿酸类结石。单能量50keV为肾结石成分分析的最佳keV,与CT常规120kVp混合能量相比,可以区分出尿酸结石、六水磷酸铵镁结石、胱氨酸结石、一水草酸钙结石及碳酸磷灰石结石。

Objective To scan kidney stone sample using single energy of spectral CT and to investigate the value of single energy of spectral CT and conventional 120kVp mixed energies to distinguish different kinds of kidney stones.Methods Sixty-six kidney Stones included uric acid stones（UA,n=8）,struvite stones（STR,n=12）,cystine stones（CYS,n=6）,Dahllite stones（DAH,n=10）,Calcium oxalate monohydrate stones（COM,n=30） were put into eleven excised pig kidneys（the upper calice,the renal pelvis and the lower calices of each kidney were inserted with 2 stones respectively） and the kidneys were placed in a water tank.Gemstone Spectral Imaging（GST） scan and conventional 120kVp scan were performed.Single energy CT value of GSI（40-140keV,5keV interval） and 120kVp mixed energy CT value were measured and calculated.The differences of CT values among different groups were compared using analysis of variance.The components of above-mentioned stones were determined by infrared spectrometer.Results After statistical treatment,the differences of 120kVp mixed energy CT value were of statistical significance（F=52.773,P=0.000）.Compared between two groups：mixed energy CT values of COM and DAH（P=0.831）,and mixed energy CT values of UA and CYS（P=0.411） were not have statistical difference;the 120kVp mixed energy CT values of rest groups had statistical differences（P0.05）.The differences of single energy（40keV-140keV,5keV interval） CT values were of statistical significance（Fvalues were269.244,201.823,121.190,97.348,88.719,80.076,71.537,63.110,55.064,47.837,41.086,35.104,30.202,26.182,22.528,19.866,17.501,15.585,14.108,12.785,11.830,P=0.000）.Compared between two groups,CT values of above-mentioned 5 groups had statistical differences at 50keV（P0.05）.Uric acid stones could be distinguished from other kinds of stones at 40keV and 45keV.Conclusion Uric acid stones could be distinguished from other kinds of stones by single energy CT value of Gemstone energy spectrum at low keV（40-50keV）.Compared to conventional 120kVp mixed energies,single energy can be used to distinguish UA,STR,CYS,COM and DAH.The components of stones can be distinguished optimally at 50keV.