MR Perfusion Weighted Imaging Research In Acute Carbon Monoxide Poisoning Of Rabbit Brain

Objective:To apply MR perfusion weighted imaging to dynamically reflect the changes of the perfusion of rabbit brain in acute carbon monoxide poisoning, compare the perfusion changes with pathologic findings, evaluate the diagnostic value of MR perfusion weighted imaging in acute carbon monoxide poisoning and attempt to find a marker which can predict the delayed encephalopathy of carbon monoxide poisoning.Methods : 60 rabbits model of acute carbon monoxide poisoning had been successfully established by static absorbing CO method and only 14 rabbits which smoothly performed MR perfusion weighted imaging in every period of pre-poisoning and post-poisoning had been included into this study. In pre-poisoning and post-poisoning (1h, 3d, 5d, 7d), Function tool software of MR perfusion imaging was used to chose two ROIs (regions of interesting) in the rabbit brain white matter section with hippocamps and measure NEI (negative enhanced integral), MSD (maximum slope of decrease) and MTT (mean transit time) value respectively, then take mean NEI, MSD and MTT of two ROIs in every rabbit brain into statistical analysis. To take mean NEI, MSD and MTT of pre-poisoning as control group, they compare mean NEI, MSD and MTT of post-poisoning with control group and combine with pathology to analyze them. We observed constantly clinical appearance of the poisoned rabbits for 60 days and the poisoned rabbits were divided into 2 groups according to having or not having symptoms of the delayed encephalopathy after carbon monoxide poisoning, the group with delayed encephalopathy and the group without delayed encephalopathy.Results :Mean NEI and MSD of 14 poisoned rabbits decreased and mean MTT prolonged in different levels 1h~7d after poisoning, 1h: NEI:90.64±15.82 MSD:248.12±17.19 and MTT:20.89±3.65 had statistical significance( P < 0.05), which compared with pre-poisoning: NEI:112.74±16.59, MSD:269.26±17.52 and MTT:16.35±3.80. Mean NEI and MSD of the group without delayed encephalopathy also reduce and mean MTT prolonged 1h~7d after poisoning, 1h:NEI:93.03±15.33, MSD:245.86±18.90 and MTT:21.24±3.43 had statistical significance( P < 0.05), which compared with pre-poisoning: NEI:113.65±17.04, MSD:268.79±18.07 and MTT:17.24±2.56; 5d:NEI:110.92±17.14,MSD:267.23±21.85 and MTT:17.26±4.31 and 7d:NEI:111.72±14.95,MSD:267.42±19.26 and MTT:17.33±3.7 had statistical significance(P < 0.05), which compared with 1h. Mean NEI and MSD of the group with delayed encephalopathy also reduce and mean MTT prolonged 1h~7d after poisoning, 1h:NEI:88.25±17.14, MSD:250.38±16.46, MTT:20.52±4.09 and 7d:NEI:92.74±15.14, MSD:250.90±16.37, MTT:20.91±5.11 had statistical significance( P < 0.05), which compared with pre-poisoning: NEI:111.84±17.44, MSD:269.73±18.39, MTT:15.46±4.78. The pathological findings coincided with the imaging appearances.Conclusions:MR perfusion weighted imaging can dynamicly reflect changes of the microcirculation of the poisoned rabbits'brain, which suggest that brain microcirculation severe disturbance is possibly one of the causes which aggravate brain injury and induce delayed encephalopathy.