Selective internal radiation therapy (SIRT) is a targeted treatment for liver tumors, particularly hepatocellular carcinoma (HCC), that involves the precise delivery of radioactive microspheres to the tumor’s blood supply. Image registration is critical to SIRT, ensuring precise alignment of diagnostic images with the treatment plan to optimize microsphere delivery and minimize side effects. In the context of SIRT, our goal was to develop a fully-automatic hybrid registration pipeline, using liver segmentation masks from a 3D UNet model to achieve performance comparable to expert registrations. The pipeline combines conventional and deep learning methods for automatic alignment of pre-treatment magnetic resonance images (MRI) on single-photon emission computed tomography (SPECT)/computed tomography (CT) images. This hybrid pipeline, which uses conventional global rigid registration and a deep learning-based approach for local deformation, outperformed conventional and manual expert registration. Quantitative assessment on a dataset of 69 HCC patients showed an improved Dice similarity coefficient (DSC) of 0.928 compared to 0.917 with the conventional methods. A subset analysis of 61 patients with expert registrations showed a mean DSC of 0.922, while our proposed method remained at a mean DSC of 0.928. These results demonstrate the effectiveness of our hybrid approach in achieving accurate liver registration, which is critical for precise microsphere delivery during SIRT. The improvement over conventional methods highlights the potential of incorporating deep learning techniques into multimodal liver registration, thereby improving the overall quality and effectiveness of SIRT in the management of HCC. Our method provides clinicians with a reliable and automated registration pipeline that can positively optimize treatment planning and reduce the burden of manual registration. As a result, our hybrid approach holds promise for more accurate and precise registration results.
KEYWORDS: 3D modeling, Image segmentation, Ultrasonography, Data modeling, Edge detection, Principal component analysis, Echocardiography, Machine learning, Databases, Image processing algorithms and systems
Segmentation of the left ventricle (LV) in 3D echocardiography is essential to evaluate cardiac function. It is however a challenging task due to the anisotropy of speckle structure and typical artifacts associated with echocardiography. Several methods have been designed to segment the LV in 3D echocardiograms, but the development of more robust algorithms is still actively investigated. In this paper, we propose a new framework combining Structured Random Forests (SRF), a machine learning technique that shows great potential for edge detection, with Active Shape Models and we compare our segmentation results with state-of-the-art algorithms. We have tested our algorithm on the multi-center, multi-vendor CETUS challenge database, consisting of 45 sequences of 3D echocardiographic volumes. Segmentation was performed and evaluated for end-diastolic (ED) and end-systolic (ES) phases. The results show that combining machine learning with a shape model provides a very competitive LV segmentation, with a mean surface distance of 2.04 ± 0.48 mm for ED and 2.18 ± 0.79 mm for ES. The ejection fraction correlation coefficient reaches 0.87. The overall segmentation score outperforms the best results obtained during the challenge, while there is still room for further improvement, e.g. by increasing the size of the training set for the SRF or by implementing an automatic method to initialize our segmentation.
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