双源CT在肾结石定性分析中的临床应用研究

Clinical application Study on the characterization of kidney stone using dual-source computed tomography in vitro and in vivo

目的评估DSCT在肾结石原位定性诊断中的准确性。方法32例需要进行经皮肾碎石取石的患者术前进行双源CT（dual-source computed tomography, DSCT） 2mm层厚、1mm增量的扫描，双球管电压分别为80kV和140kV。管电流分别为342mAs和76mAs。划出低能量和高能量扫描的成像的感兴趣区，计算低能量和高能量原位扫描下的衰减值比值（AR值），与已知结石化学成分的43枚结石水模研究获得的AR值进行对比。手术后取出的结石通过傅立叶红外光谱分析法确定结石成分。体内扫描与体外化学成分分析的结果进行对比。结果结石在水模内进行DSCT低能量和高能量扫描得出的尿酸结石AR值低于1．0，胱氨酸结石为1．13～1．21，含钙结石大于1．24。鸟粪石的AR值与含钙结石重叠，因此不能进行可靠的预测。临床研究4例患者为混合性结石（单一物质含量低于75％），4例为鸟粪石。在32倒患者当中，27例（84．4％）应用DSCT得出准确的诊断：包括全部7例尿酸结石患者（100％）、22例含钙结石患者中的19例（86％）和l铆胱氨酸结石患者。4倒鸟粪石患者未能确诊。结论DSCT可能对肾结石进行准确的原位定性诊断。

Objective To evaluate the accuracy of dual-source computed tomography in character- ization of kidney stone preoperatively. Methods 32 kidney stones with known compositions were scanned using dual-source scanner with parameters of 2-ram section thickness, l-ram increments, 80kV and 140kV tube voltage, and 342mAs and 76mAs tube currents. Regions of interest were drawn and low-and high-energy attenuation ratios were compared with attenuation ratio （AR） reference library with 43 stones of known chemical composition in phantom study. The kidney stones were ex- tracted from patients with percutaneous nephrolithotripsy and analyzed using Fourier infrared spectros- copy （FIRS）. The results of in vivo DSCT and ex vitro FIRS were compared. Results In phantom study, the AR of uric for acid stone was less than 1.0, and 1.13 to 1.21 for cystine stone and more than 1.24 for calcium stone. AR of struvite overlapped with calcium stones. In clinical study, 27 of 32 （84.4 %） patients were correctly diagnosed including all seven uric acid stones, a cysteine stone and 19 of 22 predicted as calcium stones. 4 struvite stones couldn＇t be diagnosed because of overlapped AR. Conclusion Dual-source CT can accurately characterize the composition of kidney stones in vivo.