Ren Aijun, Gao Peiyi, Sun Yilin
Beijing Neurosurgical Institute, Capital University of Medical Sciences, Beijing 100050, China.
Chin Med J (Engl). 2002 Feb;115(2):247-53.
To investigate the findings of magnetic resonance (MR) imaging and histopathology in early postoperative normal brain, and to define the correlation between MR images and histopathology.
Thirty-six New Zealand rabbits weighing 2.0 to 3.0 kg were divided into 10 groups according to different postoperative days: 1 to 10 days. A partial resection of the parietooccipital region was performed under usual aseptic conditions after the animals were anesthetized intravenously with 3% pentobarbital (30 mg/kg). MR imaging procedures consisted of pre- and postcontrast scanning and were carried out on postoperative days 1 to 10. Brain tissue samples were prepared for examination immediately after MR scanning. Histopathological examination was done under light both and electron microscopes. The findings of MR imaging were compared with histopathologic findings.
Surgical margin contrast enhancement on MR images could be seen 24 hours after surgery. The degree of contrast enhancement increased gradually up to 5 days postoperation, and no remarkable changes were present from days 5 to 10. Disruption of the blood brain barrier (BBB) was the main cause of contrast enhancement during the first 3 postoperative days. After that period, the mechanism responsible for contrast enhancement was the formation of neovascularity and a broken BBB. An increase in the amount of neovascularity played a predominant role in contrast enhancement in normal postoperative brain tissue.
The features of enhanced MR images present at the surgical margin followed a typical time course during the early postoperative period. The role of neovascularity and BBB disruption in the formation of contrast enhancement at the surgical margin varies with time. Knowledge of the features of contrast enhancement in postoperative MR images of normal brain can help in differentiating benign changes from residual malignant glioma.
研究术后早期正常脑的磁共振（MR）成像及组织病理学表现，明确MR图像与组织病理学之间的相关性。
36只体重2.0至3.0千克的新西兰兔，根据术后不同天数分为10组：术后1至10天。动物经3%戊巴比妥（30毫克/千克）静脉麻醉后，在常规无菌条件下进行顶枕区部分切除术。MR成像检查包括增强扫描前后，在术后第1至10天进行。MR扫描后立即制备脑组织样本用于检查。在光学显微镜和电子显微镜下进行组织病理学检查。将MR成像结果与组织病理学结果进行比较。
术后24小时即可在MR图像上看到手术边缘对比增强。对比增强程度在术后5天逐渐增加，术后5至10天无明显变化。血脑屏障（BBB）破坏是术后前3天对比增强的主要原因。在此之后，对比增强的机制是新生血管形成和BBB破坏。新生血管数量增加在正常术后脑组织对比增强中起主要作用。
术后早期手术边缘增强MR图像的特征呈现典型的时间过程。新生血管和BBB破坏在手术边缘对比增强形成中的作用随时间变化。了解正常脑术后MR图像对比增强的特征有助于鉴别良性改变与残留恶性胶质瘤。
