Delayed urea differential enhancement CEST (dudeCEST)-MRI with T1 correction for monitoring renal urea handling.
Delayed urea differential enhancement CEST (dudeCEST)-MRI with T1 correction for monitoring renal urea handling.
复制标题
延迟尿素差异增强 CEST (dudeCEST)-MRI，具有 T1 校正，用于监测肾脏尿素处理。
DOI：
10.1002/mrm.28583
复制
发表时间：
2021
影响因子：
3.3
通讯作者：
Vandsburger,MorielH
中科院分区：
文献类型：
--
作者：
Shin,SooHyun;Wendland,MichaelF;Vandsburger,MorielH
目的应用扩展多池洛伦兹拟合法和表观交换依赖松弛补偿方法，建立延迟尿素差示增强CEST方法，用于探讨尿素在肾脏中的循环作用。9只小鼠在7特斯拉下进行扫描，注射2M150μL尿素，然后注射生理盐水。分别于注药前、注药后20分钟、40分钟进行T1地形图和Z-波谱分析。Z谱符合7池洛伦兹模型用于CEST定量，并与尿素法测定肾匀浆进行了比较。7只小鼠用马兜铃酸造成肾脏损伤，扫描程序相同。结果模型中明显的交换依赖松弛校正了可变T1次。在延髓内侧和乳头内注射尿素后，+1ppm的尿素CEST对比度在两个时间点均显著增加。当注射后的尿素CEST与相应的基线值归一化时，尿素和生理盐水注射后的尿素CEST对比均有相同的倍数变化。肾组织匀浆尿素测定与表观交换依赖性松弛(R2=0.4687，P=0.0017)和未经T1校正的洛伦兹幅度(R2=0.4964，P=0.0011)显著相关。注射尿素和生理盐水后，肾脏损伤导致皮质T1时间延长，CEST对比度改变减少。结论注射后延迟尿素增强有助于了解肾脏尿素的处理情况。此外，注射生理盐水后CEST对比度在1.0ppm的变化可能有助于了解肾功能。
PurposeWe demonstrate a method of delayed urea differential enhancement CEST for probing urea recycling action of the kidney using expanded multi‐pool Lorentzian fitting and apparent exchange‐dependent relaxation compensation.MethodsT1correction of urea CEST contrast by apparent exchange‐dependent relaxation was tested in phantoms. Nine mice were scanned at 7 Tesla following intraperitoneal injection of 2M 150 μL urea, and later saline. T1maps and Z‐spectra were acquired before and 20 and 40 min postinjection. Z‐spectra were fit to a 7‐pool Lorentzian model for CEST quantification and compared to urea assay of kidney homogenate. Renal injury was induced by aristolochic acid in 7 mice, and the same scan protocol was performed.ResultsApparent exchange‐dependent relaxation corrected for variable T1times in phantoms. Urea CEST contrast at +1 ppm increased significantly at both time points following urea injection in the inner medulla and papilla. When normalizing the postinjection urea CEST contrast to the corresponding baseline value, both urea and saline injection resulted in identical fold changes in urea CEST contrast. Urea assay of kidney homogenate showed a significant correlation to both apparent exchange‐dependent relaxation (R2= 0.4687,P= .0017) and non–T1‐corrected Lorentzian amplitudes (R2= 0.4964,P= .0011). Renal injury resulted in increased T1time in the cortex and reduced CEST contrast change upon urea and saline infusion.ConclusionDelayed urea enhancement following infusion can provide insight into renal urea handling. In addition, changes in CEST contrast at 1.0 ppm following saline infusion may provide insight into renal function.