Vascular radiolesion as a deleterious effect of high-dose-rate intraarterial brachytherapy with samarium-153 in hypercholesterolemic rabbits.
OBJECTIVE
This study was designed to evaluate vascular morphological and morphometric changes induced by brachytherapy with samarium-153 (Sm-153) at high doses in hypercholesterolemic rabbits.


METHODS
Forty-three New Zealand White hypercholesterolemic rabbits were analyzed, and the total of 86 iliac arteries underwent balloon angioplasty injury. The rabbits were divided into three different groups: two irradiation groups (IG) assigned to 15 Gy (n=14) and 60 Gy (n=36) irradiation doses, respectively, and a control group (n = 36). Histomorphometric and qualitative histological analyses were performed for tissue evaluation.


RESULTS
Significant reductions were found in neointimal proliferation (NIP) (p< 0.0001), media area (MA) (p<0.0001) and percent stenosis (p<0.0001) in the 15-Gy IG, compared to the other groups. The 60-Gy IG had the higher rate of NIP, increase in media and vessel areas (VA) and percent stenosis. The 60-Gy IG also showed the greatest number of xanthomatous cells (60-Gy IG: 86.11% and 15-Gy IG: 14.29%, p<0.0001) and the highest amount of hyaline amorphous tissue (60-Gy IG:58.33% and 15-Gy IG:0%, p=0.0001) and vascular proliferation (60-Gy IG:30.56% and 15-Gy IG:0%, p=0.0221). No statistically significant differences were found among groups concerning other tissue analyses.


CONCLUSIONS
The high-dose irradiation of 60 Gy resulted in intense cell proliferation considered vascular radiolesion, unlike the 15-Gy dose, which was associated with an excellent inhibition of neointimal proliferation.
Précoma
Dalton Bertolim
DB
Pontifical Catholic University of Paraná, Radioimmunoassay and Nuclear Medicine Center of Paraná, Curitiba, PR, Brazil. precoma@cardiol.br
Noronha
Lúcia
L
Moura
Alvaro Vieira
AV
Yamada
Airton Seiji
AS
Knopfholz
José
J
Dusilek
César Lopes
CL
Perussolo
Rita
R
Brofman
Paulo Roberto Slud
PR
Olandoski
Márcia
M
Meneghetti
José Cláudio
JC
D000818:Animals; D001012:Aorta, Abdominal / Q000473:pathology / Q000528:radiation effects*; D001918:Brachytherapy / Q000009:adverse effects*; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging / Q000473:pathology; D006937:Hypercholesterolemia; D007083:Iliac Artery / Q000473:pathology / Q000528:radiation effects*; D011817:Rabbits; D011859:Radiography; D011868:Radioisotopes / Q000009:adverse effects*; D012493:Samarium / Q000009:adverse effects*; D012720:Severity of Illness Index; D017539:Tunica Intima / Q000473:pathology / Q000528:radiation effects; D017540:Tunica Media / Q000473:pathology / Q000528:radiation effects
D011868:Radioisotopes; D012493:Samarium