研究目的
To address the issues of lung segmentation and registration in 4D data sets by proposing a joint segmentation and registration method that extends a general simultaneous framework based on Markov Random Field, utilizes atlas segmentation for initialization, and introduces a stochastic sampling approach for similarity measurement.
研究成果
The proposed joint segmentation and registration method for 4D lung CT images based on MRF achieves more precise segmentation results (higher DICE values) and satisfactory registration accuracy (better TRE averages) compared to conventional methods. However, it underperforms in registration against some MRF methods, indicating need for optimization and handling of discontinuous motions. Future work will focus on algorithm efficiency and explicit incorporation of sliding interfaces.
研究不足
The registration results are inferior to current MRF-based methods on the DIR-Lab data set, possibly due to sampling strategy and optimization method. Discontinuous sliding motion between lung lobes and the lung rib cage interface was not considered. Execution efficiency and incorporation of discontinuous motion are areas for future improvement.
1:Experimental Design and Method Selection:
The method extends a general simultaneous segmentation and registration framework based on Markov Random Field (MRF), using a multi-resolution scheme with graph cuts optimization via α-expansion. It involves a two-layer graph for segmentation and registration connected by coherence edges, with B-spline interpolation for deformation field prior.
2:Sample Selection and Data Sources:
Experiments were performed on the DIR-Lab data set, which contains 10 pairs of 4D lung CT scans with complete breathing cycles of patients suffering from lung or esophageal cancer. The first five cases were used, with slice thickness of 2.5mm and in-plane resolution from 0.97mm to 1.16mm. Landmarks annotated by medical experts were used for evaluation.
3:5mm and in-plane resolution from 97mm to 16mm. Landmarks annotated by medical experts were used for evaluation.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Not specified in the paper.
4:Experimental Procedures and Operational Workflow:
The process starts from a coarse control grid (24mm), uses multi-level framework (4 levels), and involves calculating MRF energy, optimizing with graph cuts, interpolating deformation with B-spline, and iterating for precise displacements. Parameters were set empirically: θreg=1, λreg=0.01, θseg=0.1, θcoh=
5:01, θseg=1, θcoh=Data Analysis Methods:
1.
5. Data Analysis Methods: Registration accuracy was measured by Target Registration Error (TRE) using Euclidean distance between landmarks. Segmentation accuracy was evaluated using DICE coefficient. Comparisons were made with methods like MRF-Reg, GCV+Vem, Vemuri, and MRF-Seg.
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