Self-gated Radial MRI for Respiratory Motion Compensation on Hybrid PET/MR Systems
Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention
01/2013; 16(Pt 3):17-24. DOI: 10.1007/978-3-642-40760-4_3
Accurate localization and uptake quantification of lesions in the chest and abdomen using PET imaging is challenging due to the respiratory motion during the exam. The advent of hybrid PET/MR systems offers new ways to compensate for respiratory motion without exposing the patient to additional radiation. The use of self-gated reconstructions of a 3D radial stack-of-stars GRE acquisition is proposed to derive a high-resolution MRI motion model. The self-gating signal is used to perform respiratory binning of the simultaneously acquired PET raw data. Matching mu-maps are generated for every bin, and post-reconstruction registration is performed in order to obtain a motion-compensated PET volume from the individual gates. The proposed method is demonstrated in-vivo for three clinical patients. Motion-corrected reconstructions are compared against ungated and gated PET reconstructions. In all cases, motion-induced blurring of lesions in the liver and lung was substantially reduced, without compromising SNR as it is the case for gated reconstructions.
Available from: Shun Miao
- "Such motion model is usually formed by registering 3-D images acquired at different breathing states. To apply a cyclic model, a 1-D surrogate signal of the true motion is used to represent the current breathing state and retrieve the corresponding motion   . A common limitation of cyclic model is the assumption that respiratory motions are repeatable, i.e. the respiratory motion follows the same path from cycle to cycle. "
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ABSTRACT: Respiratory motion is a major source of error in many image acquisition applications and image-guided interventions, and motion estimation techniques have been widely applied to compensate for it. Existing respiratory motion estimation methods typically reply on breathing motion models learned from certain training data. However, none of these methods can effectively handle both intra-subject and inter-subject variations of respiratory motion. In this paper, we propose a respiratory motion estimation method that directly recovers motion ﬁelds from sparsely spaced dynamic 2-D MRIs without a learned respiratory motion model. We introduce a scatter-to-volume registration algorithm to register the dynamic 2-D MRIs with a static 3-D MRI to recover dense motion ﬁelds. The proposed method was validated on 4-D MRIs acquired from 5 volunteers with breathing pattern variability, demonstrating signiﬁcant improvements over the state of the art respiratory motion modeling method.
International Symposium on Biomedical Imaging; 04/2015
Available from: Miguel Ramalho
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ABSTRACT: MR-PET is a novel imaging modality that combines anatomic and metabolic data acquisition, allowing for simultaneous depiction of morphological and functional abnormalities with an excellent soft tissue contrast and good spatial resolution; as well as accurate temporal and spatial image fusion; while substantially reducing radiation dose when compared with PET-CT. In this review, we will discuss MR-PET basic principles and technical challenges and limitations, explore some practical considerations, and cover the main clinical applications, while shedding some light on some of the future trends regarding this new imaging technique.
12/2013; 1(1). DOI:10.1016/j.ejro.2014.09.001
Seminars in Roentgenology 07/2014; 49(3):255-70. DOI:10.1053/j.ro.2014.07.004 · 0.71 Impact Factor
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