Wu Qiaoling, Fu Xiuwei, Zhuo Zhizheng, Zhao Mingfeng, Ni Hongyan
Tianjin University of Traditional Chinese Medicine, Tianjin 300192, China.
Department of Radiology, First Central Clinical College, Tianjin Medical University, Tianjin 300192, China.
Quant Imaging Med Surg. 2019 Feb;9(2):180-187. doi: 10.21037/qims.2018.10.11.
The quantitative evaluation of liver iron concentration (LIC) is important in guiding the treatment of blood transfusion-dependent patients. Conventionally, LIC is assessed through R2*or R2 values using magnetic resonance imaging (MRI). However, most of the studies using MRI to determine iron overload were restricted by the minimum echo time, so that severe iron overload could hardly be quantified. In our study, we demonstrate a new approach to overcome the limitation of the shortest echo time using ultra-short echo time (UTE) MRI to quantify liver iron overload of varying degrees in a rat model.
Sixty female Sprague-Dawley rats were included and randomly assigned into 10 equal groups. Group 1 was not injected with iron dextran. Groups 2 to 10 were intraperitoneally injected with iron dextran at a dose of 15 mg/kg every 3 days. On every 6th day, one group was randomly selected from groups 2 to 10 for MRI scanning and liver iron concentration (LIC) detection. For groups 1 to 10, images were acquired by UTE sequence using a 3.0T MR scanner, and the T2* value and R2* value were obtained (R2* =1/T2*). In addition, LIC was measured using an atomic absorption photometer. The correlation analysis between R2* value and LIC was performed and the regression equation of R2* and LIC was established and its reliability verified.
For groups 1 to 10, R2* values and LIC ranged from 60.16±4.76 to 1,306.90±42.26 Hz and from 0.84±0.11 to 5.89±2.64 mg/g dry, respectively. The R2* value was linearly correlated to the LIC (r=0.897, P<0.001), and the linear regression equation was LIC = 0.005 × R2* + 1.783. The validation analysis results showed that the intragroup correlation coefficient (ICC) between the predicted and measured LIC was 89.5%.
The UTE sequence could be used for quantification of varying degrees of hepatic iron overload in the rat model, and the LIC could be predicted by using the R2* value on an MR 3.0T scanner.
肝铁浓度（LIC）的定量评估对于指导依赖输血患者的治疗至关重要。传统上，LIC通过磁共振成像（MRI）利用R2*或R2值进行评估。然而，大多数使用MRI测定铁过载的研究受到最小回波时间的限制，以至于严重的铁过载难以量化。在我们的研究中，我们展示了一种新方法，通过使用超短回波时间（UTE）MRI克服最短回波时间的限制，以量化大鼠模型中不同程度的肝铁过载。
纳入60只雌性斯普拉格-道利大鼠，并随机分为10个相等的组。第1组未注射右旋糖酐铁。第2组至第10组每3天腹腔注射15mg/kg剂量的右旋糖酐铁。每隔6天，从第2组至第10组中随机选择一组进行MRI扫描和肝铁浓度（LIC）检测。对于第1组至第10组，使用3.0T MR扫描仪通过UTE序列采集图像，并获得T2值和R2值（R2* = 1/T2*）。此外，使用原子吸收光度计测量LIC。进行R2值与LIC之间的相关性分析，建立R2与LIC的回归方程并验证其可靠性。
对于第1组至第10组，R2值和LIC分别为60.16±4.76至1306.90±42.26Hz以及0.84±0.11至5.89±2.64mg/g干重。R2值与LIC呈线性相关（r = 0.897，P < 0.001），线性回归方程为LIC = 0.005×R2* + 1.783。验证分析结果表明，预测的LIC与测量的LIC之间的组内相关系数（ICC）为89.5%。
UTE序列可用于量化大鼠模型中不同程度的肝铁过载，并且可以在3.0T MR扫描仪上使用R2*值预测LIC。
