犬严重烧伤后早期脑水肿影像学的观察对比

目的　探讨磁共振成像 (MRI)和放射性核素显像 (SPECT)在严重烧伤后早期脑水肿诊断中的价值。　方法　 2 6只犬随机分为对照组 (6只 )和致伤组 (烧伤后 6、12、18h和 2 4h组 ,每组各 5只 )。将致伤组犬制成 5 0 %TBSAⅢ度烧伤模型 ,并于伤后 6h输注质量浓度 5 0g/L葡萄糖液 ,建立严重烧伤后早期脑水肿模型。应用MRI和SPECT对各致伤组犬进行动态观察 ,将观察结果进行比较。　结果　严重烧伤后早期脑水肿模型MRI显示 ,脑形态学改变的最早时间为伤后 12h ,以弥漫性脑肿胀为变化特征 ,并随时间变化而逐渐明显。当T1WI标准化信号强度 (SIR)下降低于 10 %时 ,MRI难以发现 ;伤后 2 4hT2 WISIR增高 8.2 9% ,脑灰、白质分界模糊。SPECT扫描显示伤后 6h双侧脑组织呈弥漫性进行性核素浓集现象 ,12h以后各组脑核素含量摄取比值明显高于伤前 ,以伤后 2 4h组升高最为明显 (P <0 .0 1)。　结论　两种影像学方法联合应用 ,将明显提高烧伤后脑水肿早期诊断的敏感性和准确性

Comparative study of the image observation of early postburn brain edema in severely burned dogs

OBJECTIVE: To explore the diagnostic value of MRI and SPECT in early postburn brain edema in severely burned dogs. METHODS: Twenty-six mongrel dogs were randomized into control (n = 6) and burned groups in which every 5 dogs were allotted to each of following time points: 6, 12, 18 and 24 postburn hours (PBHs). The dogs in burn groups were inflicted with 50% TBSA of III degree skin burn and were infused with 5% glucose solution after 6 PBHs, so that severe early postburn brain edema was produced. MRI and SPECT were employed to observe dynamically the brain of dogs in all groups. The results were collected and compared with one another. RESULTS: The results indicated that with MRI brain morphological change of early brain edema could be shown as early as within 12 PBH and diffuse brain edema became more obvious with elapse of time. The changes might be difficult to be found by MRI when T(1)WISIR decreased below 10%. T(2)WI SIR increased by 8.29% at 24 PBH with blurred demarcation between the brain gray and white matters. There was diffused and progressive nuclide ((99)TCm-ECD) concentration in the brain tissue as shown by SPECT at 6 PBH. The radio-nuclide taking ratio increased significantly after 12 PBH, especially at 24 PBH (P < 0.01) when compared with that before burn. CONCLUSION: Combined application of MRI and SPECT could evidently increase sensitivity and specificity in the diagnosis of early postburn brain edema.