The effect of about one third craniectomy on the cerebrospinal fluid flow rate as estimated by radionuclide cisternography in normal rabbits

Since, the effect of a large cranial defect on the cerebrospinal fluid (CSF) flow rate is still not clear, this study was designed to evaluate the effect of craniectomy in rabbits by using a radionuclide technique, under in vivo physiologic conditions. Eleven male New Zealand white rabbits were examined. After the injection of technetium-99m-diethylene-triaminepenta-acetic acid into the fourth ventricle of each rabbit, dynamic acquisition for 60 min (1 min per frame) was performed pre-op followed by about one third craniectomy to each animal. Injection of the radiopharmaceutical and the imaging steps were repeated at 24 h (post-op 24 h) and at 7 days (post-op 7 d) after craniectomy. The region of interest (ROI) was drawn around the injection site and a time activity curve was generated. Slopes of each curve were calculated to detect the flow rate of the radiopharmaceutical from the injection site during 60 min. Besides, the count decreased ratio (ROIcounts of the last frame ROI counts of the first frame X100) was calculated. Our results showed that the pre-op values of the slope of the time-activity curve and the count decreased ratio were decreased 24 h and 7 d post-op but statistically significant was only the difference between the above values pre-op and 7 d post-op (P=0.04, P=0.01 respectively). In conclusion, the data of the present study indicate that the CSF flow rate in rabbits decreased 7 d after one third craniectomy.