Intravascular ultrasound analysis of nonstented adjacent segments in diffuse in-stent restenosis treated with radiation therapy with a Rhenium-188-filled balloon

The effects of β-radiation therapy on nonstented adjacent segments in in-stent restenosis have not been sufficiently evaluated. β-radiation therapy for in-stent restenosis was performed with a ¹⁸⁸Re-MAG₃-filled balloon. We evaluated the effects of β-radiation therapy on nonstented adjacent segments in in-stent restenosis by intravascular ultrasound (IVUS) analysis in 50 patients who received radiation therapy vs. 9 control patients. The changes (Δ = follow-up - postintervention) of the external elastic membrane (EEM), the lumen, and other IVUS variables were compared between the segments that received radiation therapy and the control segments. The significant differences between the two groups were as follows: Δ EEM area was 0.3 mm² in the radiation vs. -1.0 mm² in the control (P = 0.005) and Δ lumen area was 0.2 mm² vs. -1.3 mm², respectively (P < 0.001). In conclusion, compared with the changes of vessel shrinkage in the control group, significant vessel enlargement occurred in the nonstented adjacent segments that received radiation therapy.