دانلود رایگان مقاله یک استراتژی رقابتی برای تقسیم بندی دستگاه های دهلیزی و آئورت بر اساس مدل های ناپایدار

Abstract

Multiple strategies have previously been described for atrial region (i.e. atrial bodies and aortic tract) segmentation. Although these techniques have proven their accuracy, inadequate results in the mid atrial walls are common, restricting their application for specific cardiac interventions. In this work, we introduce a novel competitive strategy to perform atrial region segmentation with correct delineation of the thin mid walls, and integrated it into the B-spline Explicit Active Surfaces framework. A double-stage segmentation process is used, which starts with a fast contour growing followed by a refinement stage with local descriptors. Independent functions are used to define each region, being afterward combined to compete for the optimal boundary. The competition locally constrains the surface evolution, prevents overlaps and allows refinement to the walls. Three different scenarios were used to demonstrate the advantages of the proposed approach, through the evaluation of its segmentation accuracy, and its performance for heterogeneous mid walls. Both computed tomography and magnetic resonance imaging datasets were used, presenting results similar to the state-of-the-art methods for both atria and aorta. The competitive strategy showed its superior performance with statistically significant differences against the traditional free-evolution approach in cases with bad image quality or missed atrial/aortic walls. Moreover, only the competitive approach was able to accurately segment the atrial/aortic wall. Overall, the proposed strategy showed to be suitable for atrial region segmentation with a correct segmentation of the mid thin walls, demonstrating its added value with respect to the traditional techniques.

4. Discussion

In this study, we present a novel technique to accurately segment multiple structures. In opposition to the majority of the state-of-the-art techniques, constraints to allow thin walls between multiple structures are embedded. Furthermore, when compared with previous works addressing the same issue (Gao et al., 2012), the proposed formulation appears to present a superior performance for the delineation of heterogeneous and noisy walls, keeping a minimal wall thickness for all the different scenarios. This technique was integrated into an efficient 3D segmentation framework and the advantages of the novel competitive methodology was proven for atrial body segmentation. Note that evaluation of the mid thin walls is relevant in several clinical evaluations, such as optimal inter-atrial puncture location for transseptal puncture (Morais et al., 2016) and for the evaluation of the aortic wall thickness (Malayeri et al., 2008). To the author’s best knowledge, no previous work was presented for accurate segmentation of the atrial region with intact mid-thin walls, being a clear novelty of this work. Previous works as (Ecabert et al., 2011) and (Zuluaga et al., 2013) simply merge the different contours (if overlap happens) or prevented gap/vacuum regions, being sub-optimal strategies for clinical evaluation of these thin regions. Although no significant differences are expected between the merged contour strategies and our approach in terms of segmentation evaluation metrics (e.g. P2S or Dice), the merged contour approaches are not suitable for novel image-guided minimally invasive interventions focused on atrial wall as presented by (Bourier et al., 2016).