Usefulness of multidetector CT imaging to assess vascular stents in children with congenital heart disease: An in vivo and in vitro study

Objective: To evaluate varying CT settings to visualize pediatric vascular stents in comparison to digital angiography (DA). Background: There is a great clinical interest in substituting noninvasive methods to follow up children with congenital heart disease after interventional treatment. Materials and Methods: CT studies in small children with transcatheter placed stents were reviewed, retrospectively. Furthermore, eight stents were implanted in tubes and partially obstructed. CT exams were performed on varying scanners (4 up to 64 slices) with corresponding tube settings. The effects of dose on image quality were evaluated regarding stent size, strut thickness, and in-stent stenoses in comparison to DA. Results: Fourteen children with 28 implanted stents were identified. Significant differences between higher and lower radiation settings were not found, corresponding with the phantom, where moderate tube setting showed the best results. In vitro, there was an improvement with increasing number of detector rows, which resulted in a decrease of stent strut overestimation (295% down to 201%; P < 0.0001) and a better agreement with DA measurements for mild (78% up to 91%; P 5 0.003) and moderate in-stent stenoses (80% up to 99%; P 5 0.0001). Conclusion: Higher radiation exposure settings did not improve image quality, suggesting that the exams could be performed at a lower radiation dose.

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