Kulkarni Naveen M, Eisner Brian H, Pinho Daniella F, Joshi Mukta C, Kambadakone Avinash R, Sahani Dushyant V
Abdominal Imaging and Intervention, Harvard Medical School, Massachusetts General Hospital, Boston, MA 02114, USA. .
J Comput Assist Tomogr. 2013 Jan-Feb;37(1):37-45. doi: 10.1097/RCT.0b013e3182720f66.
This study aimed to characterize the urinary tract stones in phantom and patients using single-source dual-energy computed tomography.
Twenty stones of pure crystalline composition (uric acid [UA], struvite, cystine, and calcium oxalate monohydrate) were assessed in a phantom and 11 patients (age 39-67 years) with urinary tract stones were evaluated. An initial low-dose unenhanced CT (tube potential, 120 kilovolts [peak]; milliampere range, 150-450; noise index, 26; section thickness, 5 mm) followed by a targeted dual-energy computed tomography acquisition on a single-source dual-energy computed tomography (Discovery CT 750 HDCT, GE) was performed. Uric acid and non-UA stones were defined using a 2-material decomposition (material density-iodine/water) algorithm. The stone effective atomic number (Zeff) was used to subclassify non-UA stones. The stone attenuation (Hounsfield unit) was also studied to determine its performance in predicting the composition. Ex vivo chemical analysis of the stone served as a criterion standard.
Of the 59 verified stones (phantom, 20; patients, 39; mean size, 6 mm), there were 16 UA and 43 non-UA type. The material density images were 100% sensitive and accurate in detecting UA and non-UA stones. The Zeff accurately stratified struvite, cystine, and calcium (calcium oxalate monohydrate) stones in the phantom. In patients, Zeff identified 83% of calcium stones (n = 24), and in stones of mixed type, it resembled dominant composition. The Hounsfield unit measurements alone were 71% sensitive and 69% accurate in detecting the UA stones.
Single-source dual-energy computed tomography can accurately predict UA and non-UA stone composition in vitro and in vivo. Substratification of non-UA stones of pure composition can be made in vitro and in vivo. In stones of mixed composition, the Zeff values reflect the dominant composition.
本研究旨在利用单源双能计算机断层扫描对体模和患者的尿路结石进行特征分析。
对20块纯晶体成分的结石（尿酸[UA]、鸟粪石、胱氨酸和一水草酸钙）在体模中进行评估，并对11例（年龄39 - 67岁）患有尿路结石的患者进行评估。先进行一次低剂量非增强CT（管电压，120千伏[峰值]；毫安范围，150 - 450；噪声指数，26；层厚，5毫米），随后在单源双能计算机断层扫描（Discovery CT 750 HDCT，GE）上进行针对性双能计算机断层扫描采集。使用双物质分解（物质密度 - 碘/水）算法定义尿酸结石和非尿酸结石。结石有效原子序数（Zeff）用于对非尿酸结石进行亚分类。还研究了结石衰减（亨氏单位）以确定其在预测成分方面的性能。结石的体外化学分析作为标准对照。
在59块经证实的结石中（体模20块，患者39块；平均大小，6毫米），有16块尿酸结石和43块非尿酸结石。物质密度图像在检测尿酸结石和非尿酸结石方面的敏感性和准确性均为100%。Zeff在体模中准确地将鸟粪石、胱氨酸和钙（一水草酸钙）结石进行了分层。在患者中，Zeff识别出83%的钙结石（n = 24），在混合型结石中，它类似于主要成分。仅亨氏单位测量在检测尿酸结石方面的敏感性为71%，准确性为69%。
单源双能计算机断层扫描能够在体外和体内准确预测尿酸结石和非尿酸结石的成分。纯成分的非尿酸结石在体外和体内均可进行亚分类。在混合成分的结石中，Zeff值反映主要成分。
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