长骨生长板创伤性骨桥形成的MRI与病理学对照实验研究

MRI and pathology of bony bridge formation in posttraumatic growth plate: an experiment study

目的研究ＭＲＩ对长骨生长板创伤后骨桥形成的诊断价值。方法５周龄新西兰幼兔３０只，钻孔法制成生长板创伤模型。术后３天、１周、２周、４周、６周分别采用０．３５ＴＭＲＩ平扫和ＧｄＤＴＰＡ增强扫描；所有骨标本均行常规病理组织学检查，结果与ＭＲＩ对照。结果ＭＲＩ平扫对软骨创伤区的检出率达１００％。创伤后３天创伤区内有大量红细胞充填，ＭＲＩ平扫表现为Ｔ１ＷＩ低信号、Ｔ２ＷＩ高信号，ＧｄＤＴＰＡ增强后无强化；创伤后１周创伤区内已出现大量的肉芽组织，平扫无特异性改变，但ＧｄＤＴＰＡ增强后创伤区有明显强化；创伤后２～４周创伤区内出现数量逐渐增多的骨小梁结构，ＧｄＤＴＰＡ增强后强化带逐渐变窄、强化减弱；创伤后６周创伤区内完全由骨性结构修复，ＧｄＤＴＰＡ增强后无强化，ＭＲＩ平扫信号取决于其内部成分（红骨髓或脂肪）。结论ＭＲＩ平扫对生长板创伤检出敏感。

Purpose To evaluate the diagnostic value of MRI in bony bridge formation of posttraumatic growth plate. Methods The growth plate of proximal tibia was drilled with bony scow in 30 rabbits 5 week old . The traumatized growth plates were examined with serial MR images 3 days,1 weeks,2 weeks,4 weeks and 6 weeks after operation. All the specimens were studied histologically. The MR images were compared with pathohistology. Results The MR images of growth plate obtained 3 days after the injury showed low signal intensity on T 1WI and high signal intensity on T 2WI; no enhancement with Gd DTPA. Histological study revealed a lot of red blood cells in the defect. 1 4 weeks later, the injured areas still exhibited low signal intensity on T 1WI and high signal intensity on T 2WI ,but obviously enhanced with Gd DTPA. Histology demonstrated fibre vessel formation in the defect. With the increase of bony elements, the enhanced areas became narrow or disappeared. When the defect was completely repaired by trabeculae of the primary spongiosa, the growth plate cartilage was no longer enhanced with GD DTPA. The signal of the injured area varied according to the fat or red marrow content in the injured area. Conclusion Plain scan with SE technique provides sensitive discrimination in growth plate injury,but fails to detect fibre vessel bridge formation which can be clearly demonstrated by Gd DTPA enhanced scan.