| BACKGROUNDS Urinary calculi is a common and frequently occurring disease in the department of urology.The typical symptoms of urolithiasis have colic and hematuria.Urinary calculi may lead to renal failure,seriously affecting people's lives and health without long-term treatment.In the clinical treatment,the composition of the stones are different,so we can select different treatment options,among which there are significant differences in the treatment of uric acid stones and other stones.The formation mechanism of uric acid stones is not yet entirely clear.Generally speaking,it is associated with purine metabolic disorder and abnormal mineralization in vivo,most good curative effect can be obtained through medical treatment.Through extracorporeal shock wave lithotripsy struvite can achieve very good results(but need to prevent infection before treatment),with extracorporeal shock wave lithotripsy calcium oxalate and calcium phosphate stones are ineffective which suitable for laparoscopic pneumatic lithotripsy or percutaneous nephrolithotomy.Therefore,it is useful to reduce the occurrence of complications if we can make a definite diagnosis of stone composition before surgery.The dual energy spectrum CT can carry out the energy spectrum mode scanning through the instantaneous switching of the high and low pressure of the single ball tube,and can carry out the material analysis on the original data space level.Previous study showed that the uric acid stone can be distinguished in vitro single components of cystine and struvite,calcium oxalate stone.Due to the complex internal environment,single component spectral CT whethe or not differentiate in different components of the stones and mixed stones still need further clinical studies.The purpose of this study was to investigate the feasibility of dual energy spectrum CT in the analysis of urinary calculi,especially for the classification of uric acid and non-uric acid stones.OBJECTIVE:Based on the results of infrared spectra,the feasibility of dual energy spectrum imaging in vivo to distinguish the components of urinary calculi was discussed.METHODS Fifty-seven cases of patients with urinary calculi were included in the present eighty-nine stones,with GSI(gemstone spectral imaging)scan using AW4.4 workstation for image analysis indexes:effective atomic number of the measured GSI scan mode(Effective atomic number),the material(Materia Density)calcium water ratio(calcium water ratio,CWR),50 ke V and 70 ke V single energy CT value.The differences of 4indexes were compared.According the infrared spectrum analysis results as the reference standard.Compared with spectrum diagnosis,we can conclude that sensitivity,specificity and positive predictive value,negative predictive value of pure uric acid stones,pure non-uric acid stones,stones mixed.Retrospective study of involving 24 cases of single component calculi(11 pieces of uric acid stones,9 pieces of calcium oxalate,3 pieces of calcium phosphate stones)and 53 cases of mixed stones.Stones were respectively measuring the effective atomic number,CWR,50 ke V,70 ke V single energy CT value and we can compare the indexes of different groups with the one way anova.RESULTS:1)The effective atomic number,CWR,50 ke V CT,70 ke V single energy CT value of pure uric stone,pure non-uric acid stones and mixed stones components :pure uric acid calculi group 7.30 ± 0.32,-0.0066 ± 0.0510,493.19 ± 67.64 HU,484.67 ±77.91 HU,respectively;pure non-uric acid stone group 13.32 ± 0.57,0.2673 ±0.0590,1804.60 ± 388.05 HU,1092.20 ± 250.22 HU,respectively;mixed stones group:12.49 ± 1.14,0.2185 ± 0.0867,1537.60 ± 530.70 HU,953.97 ±312.35 HU,respectively.The infrared spectrum analysis results as the reference standard,the sensitivity for analysis pure uric acid calculi,pure non-uric acid stones and mixed stones were 100%,91.7%,97.0%,respectively;with specificity of 100%,97.4%,95.7%,respectively;with the positive predictive value of 100%,84.6% 98.5%respectively and the negative predictive value were 100%,98.7%,91.7%,respectively.2)The effective atomic number,CWR,50 ke V CT,70 ke V single energy CT values of uric acid stones,calcium oxalate,calcium phosphate stones concluding :pure uric acid calculi group 7.30 ± 0.32,-0.0066 ± 0.0510,493.19 ± 67.64 HU,484.67 ±77.91HU;calcium oxalate stones group 12.96 ± 0.64,0.2487 ± 0.0568,1731.20 ±418.41 HU,1048.10±272.60HU;calcium phosphate stones group 13.62±0.20,0.3209±0.0198,2016.70±157.27 HU,1219.40±96.74 HU.3)Grouped by infrared spectrum analysis results,the mixed stones were divided into 4 groups with the removal of stones with a maximum diameter of less than 1 cm and fewer mixed stones:COM + COD + DAH,COM + DAH,COM + UA,STR +DAH CWR.The effective atomic number,CT value,50 ke V 70 ke V CT values of 4groups were :0.2502±0.0639,12.75±0.65,1671.10±507.32 HU,1023.80±321.23HU;0.2389±0.0552,12.84±0.62,1662.60±355.54 HU,1010.60±209.77HU;0.1113± 0.0686,9.90±0.91,870.06±324.41 HU,612.08±214.59HU;0.2614±0.0277,13.09±0.31,1821.20±286.89 HU,1127.30±191.08 HU.CONCLUSION:Dual energy spectral imaging can be used to analyze the composition of the stones in vivo,4 indexes using the effective atomic number,CWR,50 ke V,70 ke V CT single energy CT value can be clearly distinguished with pure uric acid calculi,calcium oxalate,calcium phosphate stones and mixed stones composition(COM+COD+DAH,COM+DAH,COM+UA,STR+DAH). |
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