Time-Dependent Changes in T1 during Fracture Healing in Juvenile Rats: A Quantitative MR Approach
Time-Dependent Changes in T1 during Fracture Healing in Juvenile Rats: A Quantitative MR Approach
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DOI：
10.1371/journal.pone.0164284
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发表时间：
2016-11-10
期刊：
影响因子：
3.7
通讯作者：
Weinberg, Annelie M.
中科院分区：
文献类型：
--
作者：
Baron, Katharina;Neumayer, Bernhard;Weinberg, Annelie M.
与定性成像技术相比，定量磁共振成像 (qMRI) 在软组织改变的成像和确定方面具有多种优势。尽管其在大脑和肌肉组织中的应用已得到充分研究，但其是否适合量化完整和受损骨组织（尤其是儿童）的松弛时间却广为人知。在虐待儿童的案件中，对骨折的客观观察（包括其年龄确定）可能具有合法利益。因此，本研究的目的是通过 qMRI 确定未成熟大鼠完整骨骼和相应受损骨骼的时间依赖性变化，为客观且无辐射的骨折测年方法提供基础。在手术造成胫骨骨骺骨折后，使用 3T MRI 扫描仪（TimTrio，西门子 AG，埃尔兰根，德国）对 7 只 Sprague-Dawley 大鼠（雄性，4 周龄，100 5 g）进行了 35 次 MR 扫描。这些图像是在术后第 1、3、7、14、28、42 和 82 天拍摄的。获取质子密度加权和T1加权3D FLASH序列来计算骨折区域和周围组织的纵向弛豫时间T1。计算完整和受伤骨中的 T1 可以定量观察完整幼年胫骨中的骨发育以及受伤胫骨中的骨愈合过程。在这两个领域，T1 都随着加班时间而减少。为了评估完整骨和受伤骨之间 T1 行为的差异，计算了相对 T1 值（骨折），显示骨折发生后 T1 发生明显可检测的变化。这些结果表明，qMRI 不仅在检测青少年骨骼生长缺陷或发育改变的临床相关应用中具有很高的潜力，而且在法医学相关应用中也具有很高的潜力，例如在虐待或虐待儿童的情况下确定骨折的年代。
Quantitative magnetic resonance imaging (qMRI) offers several advantages in imaging and determination of soft tissue alterations when compared to qualitative imaging techniques. Although applications in brain and muscle tissues are well studied, its suitability to quantify relaxation times of intact and injured bone tissue, especially in children, is widely unknown. The objective observation of a fracture including its age determination can become of legal interest in cases of child abuse or maltreatment. Therefore, the aim of this study is the determination of time dependent changes in intact and corresponding injured bones in immature rats via qMRI, to provide the basis for an objective and radiation-free approach for fracture dating. Thirty-five MR scans of 7 Sprague-Dawley rats (male, 4 weeks old, 100 5 g) were acquired on a 3T MRI scanner (TimTrio, Siemens AG, Erlangen, Germany) after the surgical infliction of an epiphyseal fracture in the tibia. The images were taken at days 1, 3, 7, 14, 28, 42 and 82 post-surgery. A proton density-weighted and a T1-weighted 3D FLASH sequence were acquired to calculate the longitudinal relaxation time T1 of the fractured region and the surrounding tissues. The calculation of T1 in intact and injured bone resulted in a quantitative observation of bone development in intact juvenile tibiae as well as the bone healing process in the injured tibiae. In both areas, T1 decreased overtime. To evaluate the differences in T1 behaviour between the intact and injured bone, the relative T1 values (bone-fracture) were calculated, showing clear detectable alterations of T1 after fracture occurrence. These results indicate that qMRI has a high potential not only for clinically relevant applications to detect growth defects or developmental alterations in juvenile bones, but also for forensically relevant applications such as the dating of fractures in cases of child abuse or maltreatment.