Response

We thank for Nagayama and colleagues for their interest in our work (1) and welcome the opportunity to respond to the issues raised.

From the points of view of patient safety and reduction in the cost of surveillance, we agree with your option that the use of ultrasound may ultimately be the answer (2–5). However, reproducibility of ultrasound depends on observers. Standard training and formal quality assurance of ultrasound measurement should be established in the future (2–5).

The purpose of this study was to clarify the validity of measuring the maximal short-axis diameter (Dmax) of AAA in follow-up non-enhanced axial CT. Therefore, we used ultrasound for surveillance after EVAR; however, these results were not shown in this study.

In our study, no patients had more than one type of endoleak at the same time, and there were no patients with Dmax increases more clinically symptomatic. Because frequent CT studies had been done during the short follow-up period, we might find endoleaks before appearance of additional endoleak and additional clinical symptoms. Moreover, most of the endoleak cases was of type II, which is usually asymptomatic.

As suggested, this study showed that the endoleak rate of 36% was relatively high in this small series. We speculate that frequent CT studies could picked up many type II endoleaks, which might be overlooked. More recent reports show that the endoleak rates are relatively high after EVAR (6–8). Compared to these reports, our endoleak rate may not be particularly high.