The effect of 125I interstitial radiotherapy on blood-brain barrier function in normal canine brain

Publisher Website
Google Scholar
Abstract
✓ Blood-brain barrier (BBB) function was studied in 14 normal dogs at time periods from 7 to 717 days after permanent insertion of 5- to 7-mCi seeds of iodine-125 (125I) for interstitial radiation. The BBB function was measured with carbon-14-labeled alpha aminoisobutyric acid (AIB) and quantitative autoradiography, and expressed as a unidirectional blood-to-brain transfer constant, K. The 125I radiation lesions consisted of three concentric histologically and functionally distinct zones: 1) a central zone of calcified necrosis; 2) a spongy fluid-filled zone; and 3) a narrow rim (2.6 ± 0.6 mm wide) of viable brain tissue with increased permeability. Within this rim, the mean value of the K of AIB was 5.8 times that of normal cortex. Over the 7- to 392-day time period the value of K remained rather constant, and by 716 days K values had returned to normal. There was moderate regional variation in the value of K; it was highest in the white matter and lowest in the gray matter surrounding the radiation lesion. The radiation lesion progressively increased in size from 7 to 80 days, after which there was little change. This study illustrates that the geographically circumscribed radiation from 125I seeds is accompanied by similarly well-defined changes in BBB function, which may persist for over 1 year following insertion of the 125I seed. This altered BBB function is probably responsible for the cerebral edema associated with 125I interstitial radiotherapy.

This publication has 16 references indexed in Scilit: