Accuracy of 128-slice dual-source CT using high-pitch spiral mode for the assessment of coronary stents: First in vivo experience

Abstract

Objective

To investigate the accuracy of 128-slice dual-source CT using high-pitch spiral mode (HPS) for the assessment of coronary stents.

Methods

We conducted a prospective study on patients with previous stent implantation due to recurred suspicious symptoms of angina with positive findings at stress testing scheduled for coronary angiography (CA), while dual source computed tomography (DSCT) examinations were randomly done by one of the three different scan modes [HPS, sequential mode (SEQ), low-pitch spiral mode (LPS)] one week before CA examinations. The image quality, radiation dose and stent patency of DSCT were evaluated blinded to the results of CA.

Results

180 patients with total 256 stents were enrolled in this study. There was no significant difference on the image quality of DSCT by HPS (1.4 ± 0.5), SEQ (1.5 ± 0.5) and LPS (1.3 ± 0.6) (P > 0.05). The noise of images reconstructed with B26f kernel in HPS is significantly increased than in SEQ/LPS (P < 0.05), while no significant difference with images reconstructed with B46f kernel (P > 0.05). Heart rate (HR) variability had a slight impact on the image quality for HPS (P < 0.05), not for LPS/SEQ (P > 0.05). In the assessment of stent restenosis compared with CA on per-stent basis, there was no significant difference on sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of DSCT using HPS (100%, 97.1%, 83.3%, 100%), LPS (92.3%, 95.9%, 80%, 98.6%) and SEQ (93.3%, 97.3%, 87.5%, 98.6%) (P > 0.05). The effective dose of DSCT by HPS (1.0 ± 0.5 mSv) is significant less than that by SEQ (3.0 ± 1.4 mSv) or LPS (13.0 ± 5.4 mSv) (P < 0.01).

Conclusions

DSCT using HPS provides good diagnostic accuracy on coronary stent patency compared with CA, similar to that by SEQ/LPS, whereas with lower effective dose in patients with HR lower than 65 bpm.

Introduction

In recent years, coronary artery diseases had been increasing treated by coronary stent implantation. The clinical incidence of in-stent restenosis after coronary stent implantation was 20–30% for bare metal stents, and 5–10% for drug eluting stents [1], [2]. Conventional invasive coronary angiography (CA) was widely used in clinical practice to detect the in-stent restenosis as follow-up since it allowed direct visualization of the vessel lumen with both high spatial and temporal resolution [3], [4]. However, CA was an invasive procedure with both costly and severe complications sometimes [5]. Therefore a non-invasive alternative to conventional angiography for follow-up was the agent to develop in clinical practice.

Currently multi-slice computed tomography angiography (MSCT) had been established as an effective method for the detection of coronary artery diseases with high negative predictive value, and it had recently been assessed on coronary stent patency or restenosis [6], [7], [8]. However, the radiation dose in retrospective ECG-gated coronary CT angiography was still a matter of continual concern [9], [10]. Hence, MSCT had not been accepted for follow-up of coronary stents according to clinical guideline. Recently, with the advent of 128-slice dual-source CT (DSCT) system (Definition Flash, Siemens Healthcare, Forchheim, Germany), the prospective ECG-synchronized high-pitch spiral (HPS) mode applied to coronary CT angiography could reduce radiation dose while keeping or increasing the image quality [11], [12]. These reports demonstrated that HPS was a promising method for assessing native coronary arteries with lower radiation dose, however the diagnostic accuracy of this new approach to evaluate coronary stents remained unknown. The purpose of our study was to evaluate the accuracy of 128-slice dual-source CT using high-pitch spiral mode (HPS) for the assessment of coronary stents.