Histomorphometric evaluation of (198)Au endovascular brachytherapy in a renal artery restenosis model in rabbits.
OBJECTIVE
The main mid-term complication of percutaneous transluminal angioplasty of the renal artery is restenosis, which occurs in up to 50% of patients. Although no pharmacologic agent to date has been effective in preventing restenosis, both beta-ray emitters and gamma-ray emitters used in endovascular brachytherapy have been shown to reduce coronary restenosis. The objectives of this study were to evaluate the efficacy of (198)Au endovascular brachytherapy in preventing restenosis after percutaneous transluminal renal angioplasty and to determine the radiation dose to the operator.


METHODS
Twenty-one New Zealand white rabbits (10 females and 11 males) weighing an average of 3.5 kg (range, 3.2-3.8 kg) who had been fed a normal diet underwent bilateral 33% overdilatation with deendothelialization of the renal arteries. After 7 weeks, the induced renal artery stenoses were treated by percutaneous transluminal renal angioplasty. The rabbits were randomly assigned to one of three groups before receiving endovascular 25-Gy irradiation at a radial 2.0-mm depth with a 0.5 x 15 mm (198)Au wire (106 MBq). The right renal artery was irradiated in group A; the left, in group B. The rabbits in group C randomly received a right- or left-sided dummy wire. Operator exposure to radiation was measured using thermoluminescent dosimeters and ionization chambers. The rabbits were sacrificed after 3 weeks. The aorta and renal arteries were perfusion-fixed. The renal arteries were removed for histologic and histomorphometric study.


RESULTS
Forty-two renal arteries were cut into a series of 4- micro m-thick slices. Five arteries were thrombosed (two in the irradiated group and three in the control group, p > 0.05). In the patent arteries (n = 37), the average neointimal area was 0.068 mm(2) (range, 0.009-0.234 mm(2)) in 15 irradiated segments (315 slices total), whereas the average neointimal area was 0.135 mm(2) (range, 0.016-0.324 mm(2)) in 22 control segments (462 slices total) (analysis of variance, p < 0.009), showing a percentage area of restenosis of 10.4% in irradiated arteries and 43.4% in non-irradiated arteries (p < 0.0003). Radiation dose per procedure to the operator was 0.034 mSv in the index finger, 0.024 mSv in the wrist, and undectable in the body.


CONCLUSIONS
Endovascular brachytherapy with (198)Au appears to inhibit early renal artery restenosis and exposes the operator to a safe level of radiation.
Le Blanche
Alain F
AF
Department of Radiology, Hôpital Universitaire Tenon, AP-HP, 4, rue de la Chine, F-75970 Paris Cedex 20, France.
Bonneau
Michel
M
Wassef
Michel
M
Farrès
Maria-Theresa
MT
Gabez
Laure
L
Aubert
Bernard
B
Duriez
Micheline
M
Lévy
Bernard I
BI
Bigot
Jean-Michel
JM
Boudghene
Frank
F
D000800:Angioplasty, Balloon / Q000009:adverse effects*; D000818:Animals; D001918:Brachytherapy; D004195:Disease Models, Animal; D005260:Female; D006050:Gold Radioisotopes / Q000627:therapeutic use; D008297:Male; D011817:Rabbits; D011829:Radiation Dosage; D011897:Random Allocation; D012077:Renal Artery / Q000473:pathology* / Q000528:radiation effects*; D012078:Renal Artery Obstruction / Q000209:etiology / Q000473:pathology* / Q000628:therapy*; D055502:Secondary Prevention; D013997:Time Factors
D006050:Gold Radioisotopes