Assessing Lung Transplantation Ischemia-Reperfusion Injury by Microcomputed Tomography and Ultrashort Echo-Time Magnetic Resonance Imaging in a Mouse Model
Assessing Lung Transplantation Ischemia-Reperfusion Injury by Microcomputed Tomography and Ultrashort Echo-Time Magnetic Resonance Imaging in a Mouse Model
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DOI：
10.1097/rli.0b013e3182a53111
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发表时间：
2014-01
影响因子：
6.7
通讯作者：
M. Wurnig;Y. Tsushima;M. Weiger;W. Jungraithmayr;A. Boss
中科院分区：
文献类型：
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作者：
M. Wurnig;Y. Tsushima;M. Weiger;W. Jungraithmayr;A. Boss
目的缺血再灌注损伤（I/R）是肺移植术后常见的早期并发症。本研究的目的是比较磁共振成像（MRI）中的超短回波时间（UTE）序列与微型计算机断层扫描（micro-CT）参考标准，以检测肺移植小鼠模型中的I/R损伤。材料与方法6只小鼠（C57 BL/6）进行了原位肺移植，供体移植物暴露于6小时的冷缺血。在移植后24小时内使用高分辨率micro-CT（管电压，50 kV;电流，500 mA;铝过滤器，0.5 mm;体素尺寸，35 × 35 × 35 m3）和小动物MRI（4.7 T，使用线性极化全身小鼠线圈）进行成像。成像方案包括具有不同回波时间（重复时间，8毫秒;回波时间，50/75/100/500/1500/3000/4000/5000 s;体素大小，350 × 350 × 350 m3）的径向三维UTE序列。通过目视和计算对比度噪声比（CNR）值评估图像。将计算的肺实质S 0值和T2* 横向弛豫时间（MRI）与micro-CT图像中的Hounsfield单位（HU）密度进行比较。计算受试者工作特征曲线和曲线下面积，以比较诊断能力。所有样本均进行组织学检查。结果UTE MRI和micro-CT均能很好地显示I/R损伤所致的肺浸润，MRI显示CNR明显高于micro-CT（平均CNR MRI为19.7 [8.0];平均CNR micro-CT为10.3 [2.5]; P < 0.001）。测量的参数值如下：平均（SD）HU，−416（120）;平均（SD）S 0值，1655（440）;平均（SD）T2*，非移植右肺895（870）s，平均（SD）HU，29（35）;平均（SD）S 0值，2310（300）;移植左肺的平均（SD）T2* 为4550（3230）s。微CT可以更好地区分轻微浸润，而在强烈浸润，UTE MRI提供了更好的对比。接收器操作特征曲线分析得到的曲线下面积值为HU密度0.99，S 0 0.89，T2* 0.96，S 0和T2* 组合0.98。结论实验性肺移植后I/R损伤的诊断，MRI与micro-CT具有相似的诊断能力。这两种模式提供了互补的信息评估密集和轻微的浸润在肺移植后的早期阶段。因此，在肺移植后I/R损伤的评估中，UTE MRI似乎是计算机断层扫描成像的一个有前途的补充。
PurposeIschemia-reperfusion injury (I/R) is a common early complication after lung transplantation. The purpose of this study was to compare ultrashort echo-time (UTE) sequences in magnetic resonance imaging (MRI) with a microcomputed tomography (micro-CT) reference standard for detection of I/R injury in a lung transplantation mouse model. Materials and MethodsSix mice (C57BL/6) underwent orthotopic lung transplantation using donor grafts that were exposed to 6-hour cold ischemia. Imaging was performed within 24 hours after the transplantation with high-resolution micro-CT (tube voltage, 50 kV; current, 500 mA; aluminum filter, 0.5 mm; voxel size, 35 × 35 × 35 m3) and small-animal MRI at 4.7 T with a linearly polarized whole-body mouse coil. The imaging protocol comprised radial 3-dimensional UTE sequences with different echo times (repetition time, 8 milliseconds; echo time, 50/75/100/500/1500/3000/4000/5000 s; voxel size, 350 × 350 × 350 m3). Images were assessed visually and through calculation of contrast-to-noise ratio (CNR) values. Calculated S0 values and T2* transverse relaxation times (MRI) of lung parenchyma were compared with Hounsfield unit (HU) density in micro-CT images. Receiver operating characteristic curves and area under the curve values were calculated for comparison of diagnostic power. All samples underwent a histologic examination. ResultsThe results of both UTE MRI and micro-CT showed an excellent depiction of pulmonary infiltration due to I/R injury, with MRI exhibiting a significantly higher CNR (mean [SD] CNR MRI, 19.7 [8.0]; mean [SD] CNR micro-CT, 10.3 [2.5]; P < 0.001). Measured parametrical values were as follows: mean (SD) HU, −416 (120); mean (SD) S0 value, 1655 (440); mean (SD) T2*, 895 (870) s for the non–transplanted right lung and mean (SD) HU, 29 (35); mean (SD) S0 value, 2310 (300); and mean (SD) T2*, 4550 (3230) s for the transplanted left lung. Slight infiltration could be better discriminated with micro-CT, whereas, in strong infiltration, a better contrast was provided by UTE MRI. The area under the curve values resulting from the receiver operating characteristic curve analysis were 0.99 for HU density, 0.89 for S0, 0.96 for T2*, and 0.98 for the combination of S0 and T2*. ConclusionsResults show that MRI of the lung has a similar diagnostic power compared with that of micro-CT regarding the detection of I/R injury after experimental lung transplantation. Both modalities provide complementary information in the assessment of dense and slight infiltration in the early phase after lung transplantation. Therefore, UTE MRI seems to be a promising addition to computed tomographic imaging in the assessment of I/R injury after lung transplantation.