How to Fix the Edge Effect of Catheter-Based Radiation Therapy in Stented Arteries

Abstract

Background— Edge stenosis remains a serious limitation of catheter-based vascular brachytherapy (VBT). This study aims to identify the mechanisms and evaluate strategies to minimize edge restenosis in patients treated with VBT. Methods and Results— Thirty-four porcine stented coronary arteries were irradiated (doses of 15 or 22 Gy) with 192 Ir trains of either 6 seeds (23 mm) with 0 mm coverage at the distal stent edge and 10 mm at the proximal stent edge or 14 seeds (55 mm) centered at the distal edge of the stent with 27.5 and 14.5 mm coverage at the distal and proximal edges, respectively. After VBT, an additional 13-mm stent was positioned overlapping the distal margin of the first stent. Animals were killed at 28 days, and arteries were analyzed. Longer radiation margins were associated with reduced intimal area (IA) at the stent edge: 2.3±0.9, 3.6±2.0, and 5.3±2.2 mm 2 with 15 Gy for a radiation margin of 14.5, 10, and −13 mm (−13 versus 10, P =0.06; 10 versus 14.5, P =0.06). Additional stenting was associated with an increase of IA: 4.0±2.3 mm 2 at the overlapped segment. Increasing the dose to 22 Gy resulted in a reduction of the IA at the overlap segment to 1.31±0.57 mm 2 with 14 seeds (27.5 mm coverage) but was not helpful with 6 seeds (0 mm coverage): IA, 5.56±2.28 mm 2 . Conclusions— Extending the radiation margins to 14.5 mm from each end of the stent minimized the edge-effect phenomenon. A higher dose is essential to eliminate further increases in IA at the overlapped segment with additional stents.

Determinants of model of renarrowing after beta radiation for in-stent restenosis

“…Therefore, presence of subtherapeutic dose levels is more likely expected within the proximal 32 P source dose fall-off zone. Our results support the hypothesis that combination of edge injury and low-dose h-radiation induces proliferative response [20,21]. Previous reports correlating GM with the recurrent restenosis were based on the 0-mm margin definition of phenomenon, which means that GM was considered present if any injury occurred beyond the radiation source end marker, including injuries within the outer half of the source dose fall-off zone, which could allow for connection of cited and current outcomes [22,23].…”

Effects of β-radiation with a 188rhenium-filled balloon catheter system on non-stented adjacent coronary artery segments

“…However, some concern has been expressed about the risk of radiation damage to angiographically normal reference segments. IVUS analyses of the irradiated, non-injured and non-stented segments from the WRIST [7] and a recent animal study [13] revealed that the irradiation of these segments does not stimulate aberrant neointimal formation in the absence of vascular injury. However, liquid radioisotope-filled balloon systems inevitably cause balloon injury to the irradiated reference segments.…”

Direct Stenting Versus Direct Stenting Followed by Centered Beta-Radiation With Intravascular Ultrasound-Guided Dosimetry and Long-Term Anti-Platelet Treatment

“…In an animal model, a safety margin of 14.5 mm was sufficient to eliminate edge restenosis (33). Recently a 10-mm safety margin per vessel was found to have 95% specificity for avoidance of GM (34).…”