CONTRAST ENHANCEMENT IN THE CRANIOPHARYNGIOMA CYST WALL CAUSED BY IRRADIATION

Purpose: To report the occurrence, degree, frequency and duration of c ontrast enhancement in the craniopharyngioma cyst wall as caused by ir radiation. Material and Methods: Eight patients with cystic craniophar yngiomas had comparable CT or MR studies before and after either exter nal irradiation of the cyst (n=5) or P-32 instillation into the cyst ( n=3). Results. A minimal to marked increase in cyst-wall enhancement w as seen at 66-157 days after P-32 instillation in 3/3 cases and at 112 -495 days after external irradiation in 3/5 cases. The increased enhan cement was always associated with a variable interim increase in the t hickness of the enhanced cyst wall. Conclusion: CT or MR imaging after the irradiation of cystic craniopharyngiomas usually demonstrated an increase in thickness and enhancement in the cyst wall. Such changes m ay be due to the irradiation alone and do not necessarily represent in fection or increased neoplastic activity. The timing is uncertain as t o the earliest possible development of such changes and their maximum duration, but they were seen as early as 66 days post-irradiation and as late as 495 days post-irradiation.