- Poster presentation
- Open Access
Positive visualization of nitinol stent-grafts by post-processing
© Varma et al; licensee BioMed Central Ltd. 2010
Published: 21 January 2010
The emergence of new MR-compatible nitinol-based stent-grafts  allows follow-up MRI of patients with these devices to assess stent-graft and wall apposition, or monitoring endovascular aneurysm repair. In particular, the soft-tissue contrast provided by MRI holds benefit over CT and was shown to be more sensitive to endoleak detection . However, sometimes the susceptibility artifact caused by stent graft may be confused with other sources of negative contrast. Recently, Vonken et al. proposed positive visualization based on susceptibility gradient mapping (SGM) . However SGM calculates the susceptibility gradient over neighboring pixels and thus requires MR-images with very high-resolution (0.3-0.7 mm isotropic) that cannot be achieved in clinical practice. In this work we investigated the use of a new positive contrast method that maintains the original resolution and allows selective visualization of devices from the clinical MR-data.
This study focuses on the feasibility for positive visualization of nitinol stent-grafts by post-processing.
Our technique maps the echo-shift in k-space associated with the susceptibility difference from the stent-graft by applying a filter in a sequential manner in k-space. The k-space shift was determined by analyzing the drop in the Fourier transform of the filtered signal.
Application of this positive contrast technique permitted improved visualization of the stent-graft as well as the aortic lumen and wall. The poor stent-graft - wall apposition proximally and the continued perfusion of the false lumen distally provided an early non-invasive assessment of the endovascular repair and guided the clinical workflow. The proposed post-processing method does not require any additional scan and provides better depiction of a post-implant stent-graft.
This article is published under license to BioMed Central Ltd.