Objective: To evaluate the improvement of iterative reconstruction in image space (IRIS) technique in computed tomographic (CT) coronary stent imaging with sharp kernel, and to make a trade-off analysis.
Materials and Methods: Fifty-six patients with 105 stents were examined by 128-slice dual-source CT coronary angiography (CTCA). Images were reconstructed using standard filtered back projection (FBP) and IRIS with both medium kernel and sharp kernel applied. Image noise and the stent diameter were investigated. Image noise was measured both in background vessel and in-stent lumen as objective image evaluation. Image noise score and stent score were performed as subjective image evaluation.
Results: The CTCA images reconstructed with IRIS were associated with significant noise reduction compared to that of CTCA images reconstructed using FBP technique in both of background vessel and in-stent lumen (the background noise decreased by approximately 25.4% ± 8.2% in medium kernel (P <C; 0.0001) and 30.3% ± 3.4% in sharp kernel (P <C; 0.0001). The in-stent lumen noise decreased by approximately 14.2% ± 19.2% in medium kernel (P <C; 0.0001) and 27.0% ± 17.8% in sharp kernel (P <C; 0.0001)). Subjective image assessment showed that the noise of the images reconstructed with IRIS decreased compared to that with FBP. Moreover, the images with sharp kernel showed better visualization of the stent struts and in-stent lumen than that with medium kernel.
Conclusions: Iterative reconstruction in image space reconstruction can effectively reduce the image noise and improve image quality. The sharp kernel images constructed with iterative reconstruction are considered the optimal images to observe coronary stents in this study.