Study on dosimetry of endovascular brachytherapy with ~(32)P to prevent restenosis after angioplasty

Objective: To observe the dose-effect relation of endovascular brachytherapy with 32 in preventing restenosis after angioplasty and to assess the possible mechanisms of irradiation therapy reducing restenosis. Methods: In 24 rabbits, the double iliac artery atherosclerotic stenosis model was set up. We performed angioplasty and P brachytherapy at one side randomly, the absorbed doses were 9. lGy, 21. 8Gy and 33. 4Gy, respectively, the other side non-radiative therapy was served as self-controled. After five weeks, the iliac artery angiography was performed, pathological sections of iliac arteries were observed with light-microscope, and PCNA, P53 immunohistochemical techniques. We also measured morphological changes by computer analysis of photomicrographs. Results:There were no obvious changes in 9. 1Gy group. In 21. 8Gy group, the proliferation and migration of smooth muscle cells was significantly suppressed and the lumen areas did not decrease. However in 33. 4Gy group, the neointima was thick so as to make the cavity obvious stenosis, and the smooth muscle in media was shrinked and thinned, arterial thrombosis occurred in four vessels. Conclutions:Endovascular brachytherapy with P filled ballon catheter system could prevent restenosis after angioplasty. The mechanism may be due to reduce neointima formation and increase lumen size. It would be promoting apoptosis and improve the vascular remodeling.