应用超短回波时间磁共振成像序列对肾结石进行体外 MRI 成像。
In vitro MR imaging of renal stones with an ultra-short echo time magnetic resonance imaging sequence.
机构信息
Department of Radiology, Faculty of Medicine, Ain Shams University, Cairo, Egypt.
出版信息
Acad Radiol. 2012 Dec;19(12):1566-72. doi: 10.1016/j.acra.2012.07.008. Epub 2012 Sep 5.
OBJECTIVES
To characterize the magnetic resonance (MR) relaxation times (ie, T1 and T2 relaxation times) of a variety of kidney stone specimens using an ultra-short echo time (UTE) sequence and to correlate these values to their size and composition based on chemical analysis.
MATERIALS AND METHODS
This was an institutional review board-approved, Health Insurance Portability and Accountability Act-compliant study with waiver of informed consent. Between April 2009 and September 2009, stones from 36 patients underwent 1.5T MR imaging with two UTE pulse sequences to measure: 1) T2 relaxation times (repetition time [TR] = 1 second and multiple echo times [TEs] ranging from 0.1 ms up to 2 ms); 2) T1 relaxation times (TE = 0.1 ms and multiple TRs ranging from 500 ms to 2.5 seconds). A tube containing a solution of water and hydroxyapatite crystals near the stones served as reference standard. Results were compared to previous data obtained from experiments measuring the T1 and T2 of pure calcium oxalate and hydroxyapatite crystals suspended in water. Stones were submitted for chemical analysis. The stone size and composition was correlated to the relaxation time, and signal intensity.
RESULTS
The average stone size was 0.86 cm (range 0.1-3.3 cm). Twenty-one stones were visible by MR. The average size of MR-visible stones was 1.1 cm (range 0.15-3.3 cm) compared to 0.46 cm (range 0.1-0.9) for nonvisible stones. The mean T1 and T2 of MR-visible stones were 950 ms (range 138-3000 ms) and 3.12 ms (range 0.27-12 ms), respectively. The T1 (mean 1143, range 740-1583) and T1 (mean 8.31, range 4.6-12) values of calcium phosphate were longer than that for other stone compositions T1 (mean 953, range 138-3000) and T2 (mean 2.58, range 0.27-5.8; P < .05).
CONCLUSIONS
The T1- and T2-relaxation times of kidney stones are variable and depend on their composition and the size of the stones. UTE MR allows for visualization of renal stones in vitro.
目的
使用超短回波时间（UTE）序列对各种肾结石标本的磁共振（MR）弛豫时间（即 T1 和 T2 弛豫时间）进行特征描述，并根据化学成分将这些值与其大小和组成相关联。
材料与方法
这是一项经机构审查委员会批准、符合《健康保险流通与责任法案》（Health Insurance Portability and Accountability Act）并豁免知情同意的研究。在 2009 年 4 月至 2009 年 9 月期间，36 名患者的结石在 1.5T MR 成像中使用两种 UTE 脉冲序列进行测量：1）T2 弛豫时间（重复时间 [TR] = 1 秒，多个回波时间 [TE] 范围为 0.1ms 至 2ms）；2）T1 弛豫时间（TE = 0.1ms，多个 TR 范围为 500ms 至 2.5 秒）。结石附近含有水和羟基磷灰石晶体的管用作参考标准。结果与先前从实验中测量的悬浮在水中的纯草酸钙和羟基磷灰石晶体的 T1 和 T2 数据进行了比较。结石被提交进行化学分析。将结石的大小和组成与弛豫时间和信号强度相关联。
结果
结石的平均大小为 0.86cm（范围为 0.1-3.3cm）。21 个结石在 MR 上可见。MR 可见结石的平均大小为 1.1cm（范围为 0.15-3.3cm），而不可见结石的平均大小为 0.46cm（范围为 0.1-0.9cm）。MR 可见结石的 T1 和 T2 平均值分别为 950ms（范围为 138-3000ms）和 3.12ms（范围为 0.27-12ms）。磷酸钙的 T1（平均值 1143，范围 740-1583）和 T1（平均值 8.31，范围 4.6-12）值长于其他结石成分的 T1（平均值 953，范围 138-3000）和 T2（平均值 2.58，范围 0.27-5.8；P<.05）。
结论
肾结石的 T1 和 T2 弛豫时间是可变的，取决于其组成和结石的大小。UTE MR 允许在体外可视化肾结石。
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