兔眼眶植入羟基磷灰石义眼台血管化的MRI评价

Evaluation of vascularization in rabbits hydroxyapatite orbital implant by MRI

目的用 MRI 研究兔眼眶内植入羟基磷灰石(hydroxyapatite,HA)义眼台血管化过程,探讨义眼台血管化 MRI 表现和特点。方法 12只新西兰白兔眼眶内植入直径12 mm HA 义眼台,于术后第2、3、4、5、6周对所有手术兔行双眼 MR 平扫及钆喷替酸葡甲胺(Gd-DTPA)增强扫描,计算义眼台强化区体积与义眼台体积比值(V_E/V_(HA)),对结果用单因素方差分析。并于第2、4周采用随机数字法抽取2只,第6周对剩余动物义眼台行组织病理学检查。结果术后第2、3、4、5、6周 V_E/V_(HA)值分别为0.570±0.055;0.787±0.036;0.995±0.014;1.000±0.000;1.000±0.000。第2、3、4周 V_E/V_(HA)值逐渐增加,均数间比较差异有统计学意义(F=233.094,P=0),第4、5、6周均数间比较差异无统计学意义(F=0.686,P=0.520)。术后2周病理显示义眼台周边有纤维血管生长,第4、6周整个义眼台完全血管化。结论 MRI 可直观、准确地评价义眼台血管化的程度和范围。

Objective To study the fibrovascular ingrowth progression of orbital hydroxyapatite implant in rabbits with MRI, and to identify its findings and characteristics. Methods Hydroxyapatite orbital implants were implanted into the right orbits of 12 New Zealand white rabbits with the same surgery procedure. All rabbits underwent pre- and postcontrast MRI at 2, 3, 4, 5 and 6 weeks after Hydroxyapatite placement. The enhancement volumes of HA orbital implant were measured, and the Va/VHA ratios were analyzed statistically by using one-way analysis of variance. At 2 and 4 weeks, two implants were extracted and examined histopathologically. The left implants were treated in the same way at 6 weeks. Results The average VE/V,A ratios were 0. 570 ± 0. 055,0. 787 ± 0. 036,0. 995 ± 0, 014,1. 000 ± 0. 000, and 1. 000 ± 0. 000 at 2, 3, 4, 5 and 6 weeks respectively, The average VE/VHA ratios of the HA orbital implants increased gradually during the first 4 weeks after HA placement, and it showed statistical significance （ F = 233.094, P =0）. However, the average VJVHA ratios of week 5 and week 6 were not higher than that of the week 4 （F =0. 686 ,P =0. 520）. The fibrovascular tissue invaded the pores of the HA orbital implants after 2 weeks, while almost all implants were fully vascularized after 4 weeks and 6 weeks. Condusion MRI is a sensitive modality for assessing the process of vascularization in ocular HA implants.