螺旋CT扫描预测上尿路结石成分的体内研究

Determination of Upper Urinary Calculi Chemical Composition by Helical Computed Tomography in Vivo

目的:研究螺旋CT对体内上尿路结石化学成分的预测价值。方法:2005年12月～2007年9月对157例上尿路结石患者在治疗前行螺旋CT平扫,测结石CT值。定量分析各种治疗方法所获取结石的化学成分。经统计学分析,找出不同成分结石的CT值范围。结果:一水草酸钙、尿酸、羟基磷灰石三种纯结石的软组织窗平均CT值分别为(851.50±188.74)HU、(446.92±47.20)HU和(835.53±110.58)HU。尿酸结石与一水草酸钙结石、尿酸结石与羟基磷灰石之间CT值的差异均有统计学意义。13例纯尿酸结石与144例尿酸含量小于70%的其他结石的CT值差异有统计学意义。以结石的软组织窗平均CT值<500 HU为标准鉴别纯尿酸结石,其灵敏度为92.31%,特异度为96.53%,阳性预测值为70.59%,阴性预测值为99.29%。结论:结石的CT值可作为鉴别尿酸结石的一种方法,CT值小于500 HU的结石多考虑为尿酸结石。

Objective： To determine the forecast value of the chemical composition of upper urinary stones using helical computed tomography in vivo. Methods： Form december 2005 to september 2007, 157 urinary calculi were visualized on noncontrast helical computed tomography before stone removal, and the average CT-attenuation value was determinod. These calculi were obtained and their chemical compositions were analyzed. Statistical analysis were performed to find the ranges of attenuation values for different stone minerals. Results：The mean HU of the stones composed of calcium oxalate monohydrate, uric acid and hydroxyapatite were （851.50±188.74）, （446.92±47.20）, and （835.53± 110.58）, respectively. The uric acid calculi could be distinguished from calcium oxalate monohydrate and hydroxyapatite stones. A statistically significant difference was found between 13 cases pure uric acid stones and other 144 cases stones that contented uric acid less than 70% by the average CT-attenuation value. Using the HU value cutoff of 500 or lower, the sensitivity was 92.31%, specificity 96.53%, positive predictive value 70. 59%0, and negative predictive value 99.29% that a stone would be primarily pure uric acid. Conclusions： We can differentiatiate-between pure uric acid and and other stones in vivo using the CT-attenuation value of urinary calculi. An average CT-attenuation value of urinary calculi lower than 500 HU was highly suggestive of a pure uric acid stone.