Cui Helen W, Devlies Wout, Ravenscroft Samuel, Heers Hendrik, Freidin Andrew J, Cleveland Robin O, Ganeshan Balaji, Turney Benjamin W
1 Oxford Stone Group, University of Oxford , Oxford, United Kingdom .
2 Faculty of Medicine, KU Leuven , Leuven, Belgium .
J Endourol. 2017 Jul;31(7):694-700. doi: 10.1089/end.2017.0084. Epub 2017 Jun 5.
Understanding the factors affecting success of extracorporeal shockwave lithotripsy (SWL) would improve informed decision-making on the most appropriate treatment modality for an individual patient. Although stone size and skin-to-stone distance do correlate with fragmentation efficacy, it has been shown that stone composition and architecture, as reflected by structural heterogeneity on CT, are also important factors. This study aims to determine if CT texture analysis (CTTA), a novel, nondestructive, and objective tool that generates statistical metrics reflecting stone heterogeneity, could have utility in predicting likelihood of SWL success.
Seven spontaneously passed, intact renal tract stones, were scanned ex vivo using standard CT KUB and micro-CT. The stones were then fragmented in vitro using a clinical lithotripter, after which, chemical composition analysis was performed. CTTA was used to generate a number of metrics that were correlated to the number of shocks needed to fragment the stone.
CTTA metrics reflected stone characteristics and composition, and predicted ease of SWL fragmentation. The strongest correlation with number of shocks required to fragment the stone was mean Hounsfield unit (HU) density (r = 0.806, p = 0.028) and a CTTA metric measuring the entropy of the pixel distribution of the stone image (r = 0.804, p = 0.039). Using multiple linear regression analysis, the best model showed that CTTA metrics of entropy and kurtosis could predict 92% of the outcome of number of shocks needed to fragment the stone. This was superior to using stone volume or density.
CTTA metrics entropy and kurtosis have been shown in this experimental ex vivo setting to strongly predict fragmentation by SWL. This warrants further investigation in a larger clinical study for the contribution of CT textural metrics as a measure of stone heterogeneity, along with other known clinical factors, to predict likelihood of SWL success.
了解影响体外冲击波碎石术（SWL）成功的因素，将有助于就个体患者最合适的治疗方式做出明智的决策。虽然结石大小和皮肤至结石距离确实与碎石效果相关，但研究表明，CT上结构异质性所反映的结石成分和结构也是重要因素。本研究旨在确定CT纹理分析（CTTA）这一新型、无损且客观的工具，其能生成反映结石异质性的统计指标，是否有助于预测SWL成功的可能性。
对七颗自然排出的完整尿路结石进行体外扫描，采用标准CT KUB和微型CT。然后使用临床碎石机在体外将结石粉碎，之后进行化学成分分析。CTTA用于生成一些与粉碎结石所需冲击次数相关的指标。
CTTA指标反映了结石特征和成分，并预测了SWL碎石的难易程度。与粉碎结石所需冲击次数相关性最强的是平均亨氏单位（HU）密度（r = 0.806，p = 0.028）以及测量结石图像像素分布熵的CTTA指标（r = 0.804，p = 0.039）。使用多元线性回归分析，最佳模型显示熵和峰度的CTTA指标可预测92%的结石粉碎所需冲击次数的结果。这优于使用结石体积或密度。
在本体外实验环境中，已表明CTTA指标熵和峰度能有力地预测SWL碎石情况。这值得在更大规模的临床研究中进一步探究，以确定CT纹理指标作为衡量结石异质性的指标，与其他已知临床因素一起，对预测SWL成功可能性的贡献。
