| Abstract: | The dynamics of the CSF circulation in six cases of intracranial arachnoid cysts was examined by RI cisternography suing 0.5 to 1.0 mCi of 169Yb DTPA or 50 to 100 microCi of 131I HSA injected into the lumbar subarachnoid space. Serial scintigrams were obtained with rectilineal scintillation scanner at 2, 4, 6, 24 and 48 hours after injection. The communication of the cavity of arachnoid cyst and subarachnoid space was recognized in all cases. The cysts were best visualized at 24 hours in most cases. Four patterns of the entry and stasis of RI in cysts were observed as follows, 1) rapid filling of RI into the cyst and delayed clearance, 2) both rapid filling and clearance, 3) slow filling and delayed clearance, 4) no filling. |
