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[IEEE 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Atlanta, GA (2017.10.21-2017.10.28)] 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - SIRF: Synergistic Image Reconstruction Framework
摘要： The combination of positron emission tomography (PET) with magnetic resonance (MR) imaging opens the way to more accurate diagnosis and improved patient management. At present, the data acquired by PET and MR scanners are essentially processed separately, and the search for ways to improve accuracy of the tomographic reconstruction via synergy of the two imaging techniques is an active area of research. The aim of the collaborative computational project on PET and MR (CCP-PETMR), supported by the UK engineering and physical sciences research council (EPSRC), is to accelerate research in synergistic PET-MR image reconstruction by providing an open access software platform for efficient implementation and validation of novel reconstruction algorithms. In this paper, we present the first release of the Synergistic Image Reconstruction Framework (SIRF) software suite from the CCP-PETMR. SIRF provides user-friendly Python and MATLAB interfaces to advanced PET and MR reconstruction packages written in C++ (currently this uses STIR, Software for Tomographic Image Reconstruction, for PET and Gadgetron for MR, but SIRF will be able to link to other reconstruction engines in the future as appropriate). The software is capable of reconstructing images from real scanner data. Both of the available integrated clinical PET-MR systems (Siemens and GE) are being targeted, and a suitable data format exchange is being negotiated with the manufacturers.
关键词： Magnetic Resonance Imaging,Research Software Engineering,Scientific Programming,Positron Emission Tomography
更新于2025-09-09 09:28:46
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Integrated Whole Body MR/PET: Where Are We?
摘要： Whole body integrated magnetic resonance imaging (MR)/positron emission tomography (PET) imaging systems have recently become available for clinical use and are currently being used to explore whether the combined anatomic and functional capabilities of MR imaging and the metabolic information of PET provide new insight into disease phenotypes and biology, and provide a better assessment of oncologic diseases at a lower radiation dose than a CT. This review provides an overview of the technical background of combined MR/PET systems, a discussion of the potential advantages and technical challenges of hybrid MR/PET instrumentation, as well as collection of possible solutions. Various early clinical applications of integrated MR/PET are also addressed. Finally, the workflow issues of integrated MR/PET, including maximizing diagnostic information while minimizing acquisition time are discussed.
关键词： Positron emission tomography,MR/PET,Magnetic resonance imaging,Hybrid imaging
更新于2025-09-09 09:28:46
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Imaging as a Personalized Biomarker for Prostate Cancer Risk Stratification
摘要： Biomarkers provide objective data to guide clinicians in disease management. Prostate-specific antigen serves as a biomarker for screening of prostate cancer but has come under scrutiny for detection of clinically indolent disease. Multiple imaging techniques demonstrate promising results for diagnosing, staging, and determining definitive management of prostate cancer. One such modality, multiparametric magnetic resonance imaging (mpMRI), detects more clinically significant disease while missing lower volume and clinically insignificant disease. It also provides valuable information regarding tumor characteristics such as location and extraprostatic extension to guide surgical planning. Information from mpMRI may also help patients avoid unnecessary biopsies in the future. It can also be incorporated into targeted biopsies as well as following patients on active surveillance. Other novel techniques have also been developed to detect metastatic disease with advantages over traditional computer tomography and magnetic resonance imaging, which primarily rely on defined size criteria. These new techniques take advantage of underlying biological changes in prostate cancer tissue to identify metastatic disease. The purpose of this review is to present literature on imaging as a personalized biomarker for prostate cancer risk stratification.
关键词： magnetic resonance imaging (MRI),cancer staging,active surveillance,radical prostatectomy,Gleason score,radiation therapy
更新于2025-09-09 09:28:46
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Multi-modality imaging of a murine mammary window chamber for breast cancer research
摘要： Window chamber models have been developed and utilized as a means to study the complex microenvironment in which cancers develop, proliferate, and metastasize in small animals. Here we utilize rapid prototyping printer technology to construct a new plastic orthotopic mammary window chamber that is compatible with magnetic resonance imaging, nuclear imaging, and optical imaging. Optical imaging allows for high-resolution cellular and molecular level analysis of tissues; magnetic resonance imaging provides quantitative measures of tumor size, perfusion, diffusion, fat/water content relaxation parameters; and a nuclear imaging technique, called the Beta Imager, supports functional and metabolic imaging. Our demonstration of the multiple imaging capabilities of this model suggests that it can be used as a powerful platform for studying basic cancer biology and developing new cancer therapies.
关键词： cancer,optical,window chamber,imaging,nuclear,magnetic resonance
更新于2025-09-09 09:28:46
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Imaging Parameter Optimization of 3D Phase Contrast-MRA to Reduce Susceptibility-artifact and Radiofrequency-shielding around the Intracranial Stent; 頭蓋内ステントに発生する磁化率およびRF 遮断効果によるアーチファクトを低減するための3D phase contrast MRA の撮像条件の検討;
摘要： The purpose of this study was to evaluate the degree of signal attenuation generated around the stent by the susceptibility artifacts and radiofrequency (RF) shielding in phase contrast-magnetic resonance angiography (PCA) images and construct optimal PCA imaging parameters for intracranial stent lumen images. The two types of PCA images of stents (Neuroform, Enterpraise II) placed in the vascular flow phantom were imaged with different the flip angle (FA) and echo time (TE). Each original image of the vascular flow phantom was reconstructed into a coronal multiplanar reconstruction (MPR) image and a profile curve along the long axis of the stent was calculated. The reduction of in-stent signal was assessed by relative in-stent signal (RIS) calculated by comparing intra-stent signal intensity to the reference tube in the original images. When the TE was 2.3ms, the profile curve was the highest signal intensity. However, RIS had not changed by the extension of TE. When the FA was high, the RIS showed a high value, but when it exceeded 25 degrees, the signal attenuated in the distal part of the slab. The susceptibility artifacts and RF shielding generated around the stent can be reduced by the shortest TbE (2.3ms) and 20 degrees of FA in the PCA imaging.
关键词： susceptibility artifact,radiofrequency (RF) shielding,magnetic resonance angiography (MRA),stent,phase contrast
更新于2025-09-09 09:28:46
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Lanthanide-doped Hafnia Nanoparticles for Multimodal Theranostics: Tailoring the Physicochemical Properties and Interactions with Biological Entities
摘要： High-Z metal oxide nanoparticles hold promise as imaging probes and radio-enhancers. Hafnium dioxide nanoparticles have recently entered clinical evaluation. Despite promising early clinical findings, the potential of HfO2 as a matrix for multimodal theranostics is yet to be developed. Here, we investigate the physicochemical properties and the potential of HfO2-based nanoparticles for multimodal theranostic imaging. Undoped and lanthanide (Eu3+, Tb3+, and Gd3+)-doped HfO2 nanoparticles were synthesized and functionalized with various moieties, including poly(vinylpyrrolidone) (PVP), (3-aminopropyl)triethoxysilane (APTES) and folic acid (FA). We show that different synthesis routes, including direct precipitation, microwave-assisted synthesis, and sol-gel chemistry allow preparation of hafnium dioxide particles with distinct physicochemical properties. Sol-gel based synthesis allows preparation of uniform nanoparticles with dopant incorporation efficiencies superior to the other two methods. Both luminescence and contrast properties can be tweaked by lanthanide doping. We show that MRI contrast can be unified with radio-enhancement by incorporating lanthanide dopants in the HfO2 matrix. Importantly, ion leaching from the HfO2 host matrix in lysosomal-like conditions was minimal. For Gd:HfO2 nanoparticles, leaching was reduced >10× compared to Gd2O3 and no relevant cytotoxic effects have been observed in monocyte-derived macrophages for nanoparticle concentrations up to 250 μg/mL. Chemical surface modification allows further tailoring of the cyto- and hemocompatibility and enables functionalization with molecular targeting entities, which lead to enhanced cellular uptake. Taken together, the present study illustrates the manifold properties of HfO2-based nanomaterials with prospective clinical utility beyond radio-enhancement.
关键词： x-ray,magnetic resonance imaging,functionalization,bioimaging,hafnium dioxide
更新于2025-09-09 09:28:46
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Image Reconstruction Using Analysis Model Prior
摘要： The analysis model has been previously exploited as an alternative to the classical sparse synthesis model for designing image reconstruction methods. Applying a suitable analysis operator on the image of interest yields a cosparse outcome which enables us to reconstruct the image from undersampled data. In this work, we introduce additional prior in the analysis context and theoretically study the uniqueness issues in terms of analysis operators in general position and the specific 2D finite difference operator. We establish bounds on the minimum measurement numbers which are lower than those in cases without using analysis model prior. Based on the idea of iterative cosupport detection (ICD), we develop a novel image reconstruction model and an effective algorithm, achieving significantly better reconstruction performance. Simulation results on synthetic and practical magnetic resonance (MR) images are also shown to illustrate our theoretical claims.
关键词： cosparsity,iterative cosupport detection,magnetic resonance imaging,analysis model,image reconstruction
更新于2025-09-09 09:28:46
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Pattern Recognition and Signal Analysis in Medical Imaging || Computer-Aided Diagnosis for Diagnostically Challenging Breast Lesions in DCE-MRI
摘要： Breast cancer is the most common cancer among women, but has an encouraging cure rate if diagnosed at an early stage. Thus, early detection of breast cancer continues to be the key for effective treatment. Magnetic resonance (MR) imaging is an emerging and promising new modality for detection and further evaluation of clinically, mammographically, and sonographically occult cancers [134,402]. Acquisition of temporal sequences of between three and six MR images depicting the kinetics of contrast agent molecules in the breast tissue allows for detecting and assessing suspicious tissue disorders with high sensitivity, even in the mammographically dense breasts of young women. Yet, the multitemporal nature of the three-dimensional image data poses new challenges to radiologists as the key-information, reflected by subtle temporal changes of the signal intensity, is only perceivable if all images of the temporal sequence are considered simultaneously.
关键词： Computer-aided diagnosis,Dynamic contrast-enhanced MR,Magnetic resonance imaging,Non-mass-enhancing lesions,Breast cancer
更新于2025-09-04 15:30:14
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Physical nature of electrically detected magnetic resonance through spin dependent trap assisted tunneling in insulators
摘要： We show that electrically detected magnetic resonance (EDMR), through spin dependent trap assisted tunneling (SDTT) in amorphous SiC, exhibits approximately equal amplitudes at very high (8.5 T) and very low (0.013 T) magnetic fields at room temperature. This result strongly supports an SDTT/EDMR model in which spins at two nearby sites involved in a tunneling event are coupled for a finite time in circumstances somewhat analogous to spin pair coupling in the spin dependent recombination/EDMR model of Kaplan, Solomon, and Mott (KSM) [Kaplan, Solomon, and Mott, J. Phys. Lett. 39, 51 (1978)]. Since a comparable near zero magnetic field change in resistance is also observed in these samples, our results support the idea that this magnetoresistance response is also the result of a KSM-like mechanism involving SDTT. Additionally, we observe a large enhancement in SDTT/EDMR at high field (8.5 T) for temperatures below 50 K, which suggests the potential utility of SDTT in spin based quantum computation and other spintronic applications.
关键词： spin dependent trap assisted tunneling,electrically detected magnetic resonance,spintronics,amorphous SiC,magnetoresistance
更新于2025-09-04 15:30:14
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Initial experience of correlating diffusion spectral parameters with histopathologic indexes in murine colorectal tumor homografts
摘要： Purpose: To determine the correlation between continuously distributed diffusion-weighted image (DWI)-derived parameters and histopathologic indexes. Methods: Fifty-four mice bearing HCT-116 colorectal tumors were included for analysis; 12 mice were used for continuous observation, and the other 42 mice were used for break-point observation. All mice were randomly divided into radiotherapy and non-radiotherapy groups. Optical imaging and MRI were performed at different time points according to radiotherapy regimen (baseline, 24 h, 48 h, 72 h, 7 d, 14 d, and 28 d). Continuous observation data were analyzed to show the difference of dynamic changing trends of optical and MR-DWI–derived parameters between radiotherapy and non-radiotherapy groups (photon numbers, D_max, full width half maximum [FWHM], and apparent diffusion coefficient [ADC] value). Break-point observation data were used to analyze the correlation between histopathologic indices and DWI-derived parameters. Results: There was a significant difference in the changing trends of photon numbers, D_max, FWHM, and ADC value between radiotherapy and non-radiotherapy groups, especially at early time points. There was moderate negative correlation between Ki67 and percentage changes of D_max, FWHM, and ADC values (the correlation coefficients were 0.632, 0.449, and 0.586, P,0.001, P=0.008, and P,0.001, respectively). There was moderate negative correlation between survivin and percentage changes of D_max and ADC values (correlation coefficients were 0.496 and 0.473, P=0.004 and P=0.006, respectively). Conclusion: The continuously distributed DWI-derived parameters could reflect histological behavior to some extent and, thus, are potential markers for early noninvasive monitoring of tumor cell apoptosis and proliferation.
关键词： magnetic resonance imaging,colorectal cancer,murine homografts,diffusion-weighted imaging,continuously distributed
更新于2025-09-04 15:30:14