Dosimetry of a 188rhenium-labeled self-expanding stent for endovascular brachytherapy in peripheral arteries.
OBJECTIVE
Radioactive stents have been proposed as endovascular irradiation device to prevent in-stent restenosis by inhibiting neointimal proliferation. 32P-stents have been used in several studies so far, but require large-scale labeling procedures and endovascular barotrauma for stent expansion supporting the development of edge restenosis. Purpose of this study was to establish dosimetry of a self-expanding nitinol stent for peripheral vascular disease, which was radiolabeled with 188rhenium (188Re) by a dip coating technique.


METHODS
The surface of nitinol Memotherm FLEXX stents was polymer-coated providing functional NH(2) groups for diethylenetriaminepentaacetic acid (DTPA) binding, providing the ligand for the complexation of 188Re onto the stent surface. Stability of radiolabeling was tested over 48 h using an in vitro blood circulation (Chandler Loop). Radial and longitudinal dose distributions of a radiolabeled stent were obtained with a plastic scintillator dosimetry system.


RESULTS
Stents with a length of 30 mm and a diameter of 8 mm were labeled with up to 33 MBq 188Re. A total of 69+/-4% of the labeled 188Re remained stable on the stent surface after 48 h. Ninety-five percent of the infinitely accumulated dose was supplied to the target tissue within 72 h. Including correction for radioactivity washout from the stent, the infinitely accumulated dose at 1 mm radial distance from the stent surface was 1.85+/-0.19 Gy/MBq 188Re/cm stent length.


CONCLUSIONS
We developed a technique for radiolabeling of self-expanding nitinol stents with 188Re by dip coating and formation of 188Re chelate complexes. We provide dosimetry data useful for application of this beta-emitting stent for endovascular brachytherapy in peripheral vascular occlusive disease.
Nowak
B
B
Department of Nuclear Medicine, Aachen University of Technology, Pauwelsstrasse 30, 52074 Aachen, Germany. bnowak@ukaachen.de
Meyer
J M
JM
Goergen
T
T
Fluehs
D
D
Block
S
S
Guenther
R W
RW
Hoecker
H
H
Buell
U
U
D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D016491:Peripheral Vascular Diseases / Q000532:radiotherapy*; D011868:Radioisotopes; D011874:Radiometry; D012211:Rhenium / Q000627:therapeutic use*; D015607:Stents
D011868:Radioisotopes; D012211:Rhenium