Spek A, Strittmatter F, Graser A, Kufer P, Stief C, Staehler M
Department of Urology, University Hospitals Munich, Campus Grosshadern, Munich, Germany.
Department of Radiology, University Hospitals Munich, Campus Grosshadern, Munich, Germany.
World J Urol. 2016 Sep;34(9):1297-302. doi: 10.1007/s00345-015-1756-4. Epub 2016 Jan 9.
To retrospectively evaluate the accuracy of dual-energy CT (DECT) in the detection of the chemical composition of urinary calculi in correlation with infrared spectroscopic stone analysis.
We reviewed the CT scans of 255 patients who underwent DECT due to a clinical suspicion of urolithiasis. Out of this group, we included 64 patients with clinically symptomatic urolithiasis requiring stone removal. After surgical removal of the stone by ureterorenoscopy, chemical composition was analyzed with infrared spectroscopy. We correlated DECT stone characterization results with chemical stone composition based on dual-energy indices (DEI). A total of 213 renal and ureteral stones could be removed and chemically analyzed.
A total of 213 calculi were evaluated. Thirty eight out of sixty four (59 %) patients had >1 stone. DECT was used to differentiate stones by using DEI. Stones harboring calcium (CA) were color-coded in blue, while stones containing uric acid (UA) were colored red. Median DEI in UA-containing stones were 0.001. Non-UA-containing stones had a DEI between 0.073 for pure CA stones and 0.077 containing CA and other substances (p = 0.001; p = 0.03, respectively). Sensitivity of DECT was 98.4 % for differentiation of UA from non-UA-containing calculi. Specificity was 98.1 %. Mean effective radiation dose of DECT was 4.18 mSv (0.44-14.27 mSv), thus comparable to conventional CT scans of the abdomen. Conventional measurement of Hounsfield units did not correlate with stone composition.
DECT with image post-processing reliably discriminates UA-containing calculi from all other stones, but the study offered limitations. Discrimination within the non-UA stones cannot be reliably achieved but is clinically insignificant.
回顾性评估双能CT（DECT）检测尿结石化学成分的准确性，并与红外光谱结石分析进行对比。
我们回顾了255例因临床怀疑尿路结石而接受DECT检查的患者的CT扫描结果。在这组患者中，我们纳入了64例有临床症状且需要进行结石清除的尿路结石患者。通过输尿管肾镜手术取出结石后，用红外光谱分析其化学成分。我们将基于双能指数（DEI）的DECT结石特征结果与结石化学成分进行关联分析。总共213颗肾和输尿管结石被取出并进行了化学分析。
共评估了213颗结石。64例患者中有38例（59%）有不止1颗结石。使用DEI通过DECT对结石进行鉴别。含钙（CA）结石被编码为蓝色，而含尿酸（UA）结石被编码为红色。含UA结石的DEI中位数为0.001。不含UA的结石的DEI在纯CA结石为0.073和含CA及其他物质的结石为0.077之间（p分别为0.001和0.03）。DECT区分含UA结石与不含UA结石的敏感性为98.4%，特异性为98.1%。DECT的平均有效辐射剂量为4.18 mSv（0.44 - 14.27 mSv），因此与传统腹部CT扫描相当。传统的亨氏单位测量与结石成分无关。
DECT结合图像后处理能够可靠地将含UA结石与其他所有结石区分开来，但本研究存在局限性。在不含UA的结石内部进行区分无法可靠实现，不过在临床上并不重要。
