Kacker Ravi, Zhao Lee, Macejko Amanda, Thaxton Colby S, Stern Jeff, Liu Jonathan J, Nadler Robert B
Department of Urology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.
J Urol. 2008 May;179(5):1866-71. doi: 10.1016/j.juro.2008.01.038. Epub 2008 Mar 18.
Accurate prediction of shock wave lithotripsy success for given patient and radiographic parameters will lead to improved selection of patients for shock wave lithotripsy vs more invasive treatment. In this study we determined which radiographic parameters are the most predictive of shock wave lithotripsy success, and present a method to incorporate these into current and future models based on nonradiographic parameters.
A retrospective case-control study was performed to determine average, maximum and standard deviation of stone attenuation values, stone size and skin-to-stone distance on preoperative noncontrast computerized tomography for 220 patients successfully treated with shock wave lithotripsy and 105 patients in whom shock wave lithotripsy failed.
Average stone attenuation is the best independent predictor of shock wave lithotripsy success as determined by the Student t test (p <0.0001) and receiver operating characteristic curves. Odds and likelihood ratios are provided for shock wave lithotripsy success for incremental average HU cutoffs. An average HU cutoff can be established over which the refined probability of success is below an arbitrary minimally acceptable cutoff of a 60% stone-free rate. Using pre-test probabilities of shock wave lithotripsy success from nomograms in the literature, our data suggest that shock wave lithotripsy should be first line therapy for solitary 6 to 10 mm stones with an average stone attenuation of less than 1,000 and 640 HU for the proximal ureter and renal pelvis, respectively.
Average stone attenuation is a convenient radiographic measure that can be used to refine a known probability of shock wave lithotripsy success. Clinical HU cutoff guidelines can be determined based on current or future predictive nomograms based on other parameters.
对于给定患者和影像学参数，准确预测冲击波碎石术的成功率将有助于更好地选择接受冲击波碎石术而非更具侵入性治疗的患者。在本研究中，我们确定了哪些影像学参数最能预测冲击波碎石术的成功率，并提出一种方法将这些参数纳入基于非影像学参数的现有及未来模型中。
进行了一项回顾性病例对照研究，以确定220例成功接受冲击波碎石术的患者以及105例冲击波碎石术失败的患者术前非增强计算机断层扫描上结石衰减值、结石大小和皮肤至结石距离的平均值、最大值和标准差。
通过学生t检验（p<0.0001）和受试者操作特征曲线确定，平均结石衰减是冲击波碎石术成功的最佳独立预测指标。给出了不同平均HU截点下冲击波碎石术成功的优势比和似然比。可以建立一个平均HU截点，超过该截点，成功的精确概率低于任意设定的最低可接受的无石率60%的截点。利用文献中列线图得出的冲击波碎石术成功的预测试概率，我们的数据表明，对于孤立的6至10mm结石，若近端输尿管和肾盂的平均结石衰减分别小于1000HU和640HU，冲击波碎石术应作为一线治疗方法。
平均结石衰减是一种便捷的影像学测量指标，可用于细化已知的冲击波碎石术成功概率。可根据基于其他参数的现有或未来预测列线图确定临床HU截点指南。
