Dissertations / Theses: 'Water/fat imaging'

1

An, Li. "Water-fat imaging and general chemical shift imaging with spectrum modeling." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0032/NQ38848.pdf.

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2

Huang, Fangping. "Water and Fat Image Reconstruction in Magnetic Resonance Imaging." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1309791802.

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Mehemed, Taha Mohamed M. "Fat-Water Interface on Susceptibility-Weighted Imaging and Gradient-Echo Imaging: Comparison of Phantoms to Intracranial Lipomas." Kyoto University, 2014. http://hdl.handle.net/2433/193572.

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4

Berglund, Johan. "Separation of Water and Fat Signal in Magnetic Resonance Imaging : Advances in Methods Based on Chemical Shift." Doctoral thesis, Uppsala universitet, Enheten för radiologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-158111.

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Magnetic resonance imaging (MRI) is one of the most important diagnostic tools of modern healthcare. The signal in medical MRI predominantly originates from water and fat molecules. Separation of the two components into water-only and fat-only images can improve diagnosis, and is the premier non-invasive method for measuring the amount and distribution of fatty tissue. Fat-water imaging (FWI) enables fast fat/water separation by model-based estimation from chemical shift encoded data, such as multi-echo acquisitions. Qualitative FWI is sufficient for visual separation of the components, while quantitative FWI also offers reliable estimates of the fat percentage in each pixel. The major problems of current FWI methods are long acquisition times, long reconstruction times, and reconstruction errors that degrade image quality. In this thesis, existing FWI methods were reviewed, and novel fully automatic methods were developed and evaluated, with a focus on fast 3D image reconstruction. All MRI data was acquired on standard clinical scanners. A triple-echo qualitative FWI method was developed for the specific application of 3D whole-body imaging. The method was compared with two reference methods, and demonstrated superior image quality when evaluated in 39 volunteers. The problem of qualitative FWI by dual-echo data with unconstrained echo times was solved, allowing faster and more flexible image acquisition than conventional FWI. Feasibility of the method was demonstrated in three volunteers and the noise performance was evaluated. Further, a quantitative multi-echo FWI method was developed. The signal separation was based on discrete whole-image optimization. Fast 3D image reconstruction with few reconstruction errors was demonstrated by abdominal imaging of ten volunteers. Lastly, a method was proposed for quantitative mapping of average fatty acid chain length and degree of saturation. The method was validated by imaging different oils, using gas-liquid chromatography (GLC) as the reference. The degree of saturation agreed well with GLC, and feasibility of the method was demonstrated in the thigh of a volunteer. The developed methods have applications in clinical settings, and are already being used in several research projects, including studies of obesity, dietary intervention, and the metabolic syndrome.

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Sun, Ling. "3D Mellisa : a new three dimensional fat/water image acquisition technique for magnetic resonance imaging /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487854314873059.

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Shibahara, Eriko, Hiroshi Fukatsu, Shinji Naganawa, Tokiko Ito, Eriko Iwayama, Takeo Ishigaki, Toru Segawa, and Waguo Zhang. "Water fat separation using the single acquisition "sandwich" type 3-point Dixon method to optimize knee joint scans." Nagoya University School of Medicine, 2000. http://hdl.handle.net/2237/5354.

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Bookwalter, Candice Anne. "CONTINUOUS SAMPLING IN MAGNETIC RESONANCE IMAGING." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1194049081.

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Mendoza, Michael A. "Water Fat Separation with Multiple-Acquisition Balanced Steady-State Free Precession MRI." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/4304.

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Magnetic resonance imaging (MRI) is an important medical imaging technique for visualizing soft tissue structures in the body. It has the advantages of being noninvasive and, unlike x-ray, does not rely on ionizing radiation for imaging. In traditional hydrogen-based MRI, the strongest measured signals are generated from the hydrogen nuclei contained in water and fat molecules.Reliable and uniform water fat separation can be used to improve medical diagnosis. In many applications the water component is the primary signal of interest, while the fat component represents a signal which can obscure the underlying pathology or other features of interest. In other applications the fat signal is the signal of interest. There currently exist many techniques for water fat separation. Dixon reconstruction techniques take multiple images acquired at select echo times with specific phase properties. Linear combinations of these images produce separate water and fat images. In MR imaging, images with high signal-to-noise ratio (SNR), that can be generated in a short time, are desired. Balanced steady-state free precession (bSSFP) MRI is a technique capable of producing images with high SNR in a short imaging time but suffers from signal voids or banding artifacts due to magnetic field inhomogeneity and susceptibly variations. These signal voids degrade image quality. Several methods have been developed to remove these banding effects. The simplest methods combine images across multiple bSSFP image acquisitions. This thesis describes a technique in water fat separation I developed which combines the advantages of bSSFP with Dixon reconstruction in order to produce robust water fat decomposition with high SNR in a short imaging time, while simultaneously reducing banding artifacts which traditionally degrade image quality. This algorithm utilizes four phased-cycled bSSFP acquisitions at specific echo times. Phase sensitive post-processing and a field map are used to prepare the data and reduce the effects of field inhomogeneities. Dixon reconstruction is then used to generate separate water and fat images.

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Salvati, Roberto. "Development of Magnetic Resonance Imaging (MRI) methods for in vivo quantification of lipids in preclinical models." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1B026/document.

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L'obésité est associée à une augmentation de la morbidité et de la mortalité liée à de nombreuses maladies, y compris le diabète de type 2, l'hypertension et des pathologies hépatiques menant à une surcharge lipidique d’origine non alcoolique. Récemment, l’imagerie par résonance magnétique (IRM) est devenue la méthode de choix pour la quantification non invasive de la graisse. Dans cette thèse, les méthodes d'IRM ont été étudiées sur un scanner préclinique de 4.7T in vitro (fantômes MR) et in vivo (souris). Deux algorithmes de quantifications de la graisse -la méthode de Dixon et l’algorithme IDEAL- ont été considérés. Les performances de l'algorithme IDEAL ont été analysées en fonction de propriétés des tissus (T2*, fraction de graisse et modèle spectral de la graisse), de paramètres d'acquisition IRM (temps d’écho, nombre d'échos) et de paramètres expérimentaux (SNR et carte de champ). Sur les fantômes, l'approche standard single-T2* IDEAL a montré certaines limites qui pourraient être surmontées en optimisant le nombre d'échos. Une nouvelle méthode, pour déterminer les valeurs de vérité terrain pour T2* de l'eau et pour T2* de la graisse, a été proposée. Pour les mesures in vivo, différentes analyses ont été effectuées en utilisant l'algorithme IDEAL sur le foie et les muscles. L'analyse statistique sur les mesures de ROI a montré que le choix optimal du nombre d'échos est égal à trois pour la quantification de la graisse et six ou plus pour la quantification du T2*. Les valeurs de la fraction de graisse, calculées avec l'algorithme IDEAL, étaient statistiquement comparables aux valeurs obtenues avec la méthode de Dixon. Enfin, un procédé pour générer des signaux de référence mimant les systèmes eau-graisse (Fat Virtual Phantom MRI), sans l'aide d'objets physiques, a été proposé. Ces fantômes virtuels, qui présentent des caractéristiques de bruit réalistes, représentent une alternative intéressante aux fantômes physiques pour fournir un signal de référence dans les mesures IRM
Obesity is associated with increased morbidity and mortality linked to many diseases, including type 2 diabetes, hypertension and disease nonalcoholic fatty liver. Recently, 1H magnetic resonance imaging (MRI) has emerged as the method of choice for non-invasive fat quantification. In this thesis, MRI methodologies were investigated for in vitro (MR phantoms) and in vivo (mice) measurements on a 4.7T preclinical scanner. Two algorithms of fat quantifications – the Dixon’s method and IDEAL algorithm – were considered. The performances of the IDEAL algorithm were analyzed as a function of tissue properties (T2*, fat fraction and fat spectral model), MRI acquisition parameters (echo times, number of echoes) and experimental parameters (SNR and field map). In phantoms, the standard approach of single-T2* IDEAL showed some limitations that could be overcome by optimizing the number of echoes. A novel method to determine the ground truth values of T2* of water and T2* of fat was here proposed. For in vivo measurements, different analyses were performed using the IDEAL algorithm in liver and muscle. Statistical analysis on ROI measurements showed that the optimal choice of the number of echoes was equal to three for fat quantification and six or more for T2* quantification. The fat fraction values, calculated with IDEAL algorithm, were statistically similar to the values obtained with Dixon’s method. Finally, a method for generating reference signals mimicking fat-water systems (Fat Virtual Phantom MRI), without using physical objects, was proposed. These virtual phantoms, which display realistic noise characteristics, represent an attractive alternative to physical phantoms for providing a reference signal in MRI measurements

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Belbaisi, Adham. "Deep Learning-Based Skeleton Segmentation for Analysis of Bone Marrow and Cortical Bone in Water-Fat Magnetic Resonance Imaging." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-297528.

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A major health concern for subjects with diabetes is weaker bones and increased fracture risk. Current clinical assessment of the bone strength is performed by measuring Bone Mineral Density (BMD), where low BMD-values are associated with an increased risk of fracture. However, subjects with Type 2 Diabetes (T2D) have been shown to have normal or higher BMD-levels compared to healthy controls, which does not reflect the recognized bone fragility among diabetics. Thus, there is need for more research about diabetes-related bone fragility to find other factors of impaired bone health. One potential biomarker that has recently been studied is Bone Marrow Fat (BMF). The data in this project consisted of whole-body water-fat Magnetic Resonance Imaging (MRI) volumes from the UK Biobank Imaging study (UKBB). Each subject in this data has a water volume and a fat volume, allowing for a quantitative assessment of water and fat content in the body. To analyze and perform quantitative measurements of the bones specifically, a Deep Learning (DL) model was trained, validated, and tested for performing fully automated and objective skeleton segmentation, where six different bones were segmented: spine, femur, pelvis, scapula, clavicle and humerus. The model was trained and validated on 120 subjects with 6-fold cross-validation and tested on eight subjects. All ground-truth segmentations of the training and test data were generated using two semi-automatic pipelines. The model was evaluated for each bone separately as well as the overall skeleton segmentation and achieved varying accuracy, performing better on larger bones than on smaller ones. The final trained model was applied on a larger dataset of 9562 subjects (16% type 2 diabetics) and the BMF, as well as bone marrow volume (BMV) and cortical bone volume (CBV), were measured in the segmented bones of each subject. The results of the quantified biomarkers were compared between T2D and healthy subjects. The comparison revealed possible differences between healthy and diabetic subjects, suggesting a potential for new findings related to diabetes and associated bone fragility.

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Johnson, David Herbert. "Phenotyping Rodent Models of Obesity Using Magnetic Resonance Imaging." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1250086728.

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12

Olhager, Elisabeth. "Studies on adipose tissue, body fat, body water and energy expenditure during the first four months of infancy using magnetic resonance imaging, skinfold measurements and the doubly labelled water method /." Linköping : Univ, 2003. http://www.bibl.liu.se/liupubl/disp/disp2003/med798s.pdf.

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13

Palosaari, K. (Kari). "Quantitative and semiquantitative imaging techniques in detecting joint inflammation in patients with rheumatoid arthritis:phase-shift water-fat MRI method for fat suppression at 0.23 T, contrast-enhanced dynamic and static MRI, and quantitative ^99mTc-nanocolloid scintigraphy." Doctoral thesis, University of Oulu, 2008. http://urn.fi/urn:isbn:9789514288623.

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Abstract The purpose of this study was to evaluate the value of 0.23T low-field magnetic resonance imaging (MRI) and nanocolloid (NC) scintigraphy in assessing joint pathology associated with rheumatoid arthritis (RA). Fat suppression methods combined with contrast media enhancement aid in distinguishing enhancing inflamed tissue from the surrounding fat, especially in the imaging of arthritic joints. The feasibility and image quality of a phase-shift water-fat MRI method for fat suppression at low-field 0.23T open configuration MR scanner was evaluated. The technique was combined with contrast-enhanced imaging to assess the conspicuity of synovial hypertrophy in the joints of 30 RA patients. Improved conspicuity and delineation of synovitis was detected with this method. However, because of a great amount of manual post processing, future development is needed to make this method more feasible. Contrast-enhanced MRI and NC scintigraphy may provide objective and quantitative information about the inflammatory activity in arthritic joints. The value of quantitative and semiquantitative measures of inflammation derived from NC scintigraphy and low-field MRI of the wrist joint of 28 early RA patients was evaluated. Furthermore, it was investigated whether these parameters have predictive value of further erosive development during two years of follow-up. Strong correlations were detected between the NC scintigraphy and MRI measures, and these parameters were associated with laboratory markers of inflammation. During the two-year follow-up, the initial MRI and NC scintigraphy measures were closely related with the progression of wrist joint erosions. Small erosive-like bone defects can occasionally be found in wrist MRI of patients without clinically overt arthritis. The prevalence of these lesions was studied in bilateral wrist MRI examinations of 31 healthy persons. Small lesions resembling erosions were detected in 14 out of 31 subjects. Altogether 24 of the 930 wrist bones evaluated showed such lesions (3%). Thus small changes resembling erosions can be found in the wrist MRI of healthy subjects; the significance of these findings must always be interpreted with reference to the clinical picture. In conclusion, early RA patients with high local inflammatory activity, as detected by NC scintigraphy and MRI are at risk of developing further bone damage. Furthermore, in the follow-up of early RA patients, if clinically sustained response is not achieved, these methods help to identify patients who need more intensive drug treatment.

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Daudé, Pierre. "Quantification du tissu adipeux épicardique à haut champ par IRM-Dixon, pour le phénotypage de la cardiomyopathie diabétique." Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0333.

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L’amélioration de la prise en charge des complications cardiaques dans les maladies métaboliques, obésité et diabète, est un enjeu majeur de notre société. La mesure du tissu adipeux épicardique (TAE), dépôt de graisse attaché au cœur, est un élément diagnostique émergent et prometteur pour identifier les patients à risque. Nous avons développé l’automatisation de cette mesure sur des images IRM de routine par apprentissage profond. Puis, une technique IRM innovante a été proposée pour mesurer et caractériser le TAE en 3D, réunissant : une acquisition en respiration libre, une reconstruction des images robuste au mouvement cardio-respiratoire et aux imperfections de l’IRM, un algorithme de caractérisation de la graisse optimisé et validé et la connaissance de la composition d’échantillons ex-vivo de TAE. L’ensemble permet la caractérisation in vivo et non-invasive du TAE, élément diagnostique novateur du risque cardio-métabolique
Improving the management of cardiac complications in metabolic diseases, obesity and diabetes, is a major challenge for our society. The measurement of epicardial adipose tissue (EAT), a fat depot attached to the heart, is an emerging and promising diagnosis to identify patients at risk. We developed the automation of this measurement on routine MRI images by deep learning. Then, an innovative MRI technique was proposed to measure and characterize the EAT in 3D, combining: a free-breathing acquisition, an image reconstruction robust to cardio-respiratory motion and MRI imperfections, an optimized and validated fat characterization algorithm and the knowledge of the composition of ex-vivo EAT samples. Together, this allows for in vivo, non-invasive characterization of EAT, a novel diagnosis for cardiometabolic risk

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Webilor, Raymond. "A dual frequency inductive flow tomography system for fast imaging of water velocity profiles in water continuous multiphase flows." Thesis, University of Huddersfield, 2018. http://eprints.hud.ac.uk/id/eprint/34606/.

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Measurement of the velocity profile of water continuous multiphase flows is important because it can enable production optimisation and avoidance of unwanted flow assurance issues in both mining and oil and gas industries. However, accurate measurement of the velocity profile of the continuous phase in multiphase flows when they are time dependent or transient is still a challenge in such industries. Many available commercial multiphase flow meters, which are not able to directly measure the velocity profile of the continuous phase, use radioactive measurement techniques. Radioactive measurement techniques have many safety issues involving exposure to radiation, which is very harmful and is a known cause of cancer in humans. This thesis describes the development of a non-radioactive based flow meter, which relies on the measurement principle of a multi-electrode electromagnetic flow meter. This flow meter is capable of measuring the velocity profile of the conducting continuous phase in both single and multiphase flows tens (or potentially even hundreds) of times every second. The images of velocity profile of the conducting continuous phase in both single and multiphase flows were reconstructed using inductive flow tomography technique (IFT) from flow induced potential difference measurements obtained from a flush mounted array of electrodes on the wall of the flow meter. The designed and developed IFT system presented in this thesis consists of (i) a flow meter body, which has coils for generating magnetic fields and an array of 16-electrodes to enable sensing of flow induced potential differences; (ii) analogue electronic circuits for coil excitation and for signal conditioning of flow induced potential difference measurements and (iii) a computer unit for controlling system hardware and data acquisition and processing (which includes the mathematical algorithm for reconstructing the velocity profile of the continuous phase). Performance of the IFT system was tested in vertical single-phase ‘water only’ flows and in both vertical and inclined two-phase air-in-water and solids-in-water flows. The velocity profile measurements from the IFT system were in good agreement with reference measurements and were consistent with previous work cited in the literature. In addition, the IFT system was tested in both single-phase ‘water only’ and air-in-water transient vertical flows, for which the velocity profiles were measured with improved accuracy and temporal resolution.

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Amurao, Maxwell Leland Ramirez. "Investigating collagen hydration with micro computed tomography a dissertation /." San Antonio : UTHSC, 2008. http://proquest.umi.com.libproxy.uthscsa.edu/pqdweb?did=1625775011&sid=1&Fmt=2&clientId=70986&RQT=309&VName=PQD.

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Rambow, Olen. "Direct Water and Fat Determination in Two-Point Dixon Imaging." Thesis, 2013. http://hdl.handle.net/1911/72028.

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The Dixon technique is a well-established method in magnetic resonance imaging for obtaining separate images of water and fat. Here we present a generalized solution to the two-point Dixon problem with a geometric interpretation, allowing for flexible echo times and a multi-peak fat model. By simulation and experiment, we have analyzed the dependence on the echo times of the error in the water, fat, and relative background phasor values due to both signal noise and T2* decay. Furthermore, we have demonstrated that broken symmetry due to the multi-peak nature of fat enables direct water and fat determination without phase correction, and we have quantified the reliability of this technique as a function of the echo times. The results may provide valuable guidance for selecting scan parameters to balance the objectives of optimizing fat-water identification, minimizing error in the pixel values, and minimizing total scan time.

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Oliveira, Maria Manuela França. "MR imaging biomarkers in diffuse liver diseases: quantification of fat, water and iron deposits." Doctoral thesis, 2017. https://repositorio-aberto.up.pt/handle/10216/106075.

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Oliveira, Maria Manuela França. "MR imaging biomarkers in diffuse liver diseases: quantification of fat, water and iron deposits." Tese, 2017. https://repositorio-aberto.up.pt/handle/10216/106075.

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Wyatt, Cory Robert. "Development of MR Thermometry Strategies for Hyperthermia of Extremity and Breast Tumors." Diss., 2010. http://hdl.handle.net/10161/2438.

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Numerous studies have shown that the combination of radiation therapy and hyperthermia, when delivered at moderate temperatures (40°-45°C) for sustained times (30-90 minutes), can help to provide palliative relief and augment tumor response, local control, and survival. However, the dependence of treatment success on achieved temperature highlights the need for accurate thermal dosimetry, so that the prescribed thermal dose can be delivered to the tumor. This can be achieved noninvasively with MR thermometry. However, there are many challenges to performing MR thermometry in the breast, where hyperthermia of locally advanced breast cancer can provide a benefit. These include magnetic field system drift, fatty tissue, and breathing motion.

The purpose of this research was to develop a system for the hyperthermia treatment of LABC while performing MR thermometry. A hardware system was developed for performing the hyperthermia treatment within the MR bore. Methods were developed to correct for magnetic field system drift and to correct for breath hold artifacts in MR thermometry of the tumor using measurement of field changes in fat references. Lastly, techniques were developed for measuring temperature in the fatty tissue using multi-echo fat water separation methods, reducing the error of performing MR thermometry in such tissues. All of these methods were characterized with phantom and in vivo experiments in a 1.5T MR system.

The results of this research can provide the means for successful hyperthermia treatment of LABC with MR thermometry. With this thermometry, accurate thermal doses can be obtained, potentially providing improved outcomes. However, these results are not only applicable in the breast, but can also be used for improved MR thermometry in other areas of the body, such as the extremities or abdomen.

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Chiu, Yu-Chih, and 邱毓智. "Discrimination of White Adipose Tissue and Brown Adipose Tissue in Magnetic Resonance Imaging - Post-Processing Method Development for Determining the Percentage of Water and Fat in the Image." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/23655324427645917470.

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碩士
國立中正大學
化學暨生物化學研究所
101
In clinical applications, Magnetic resonance imaging is a powerful tool in diagnosis. However, there are still many clinical problems need to be solved. Currently, literature showed that using Breath-hold mutliecho MRI and IDEAL MRI to observe the distribution of adipose tissue and determination the fat percentage. However, MRI is likely to cause errors in judgment, due to the magnetic field, or image contrast or other factors. Therefore, the main purpose of this experiment is combining the basic theory to improve the practical application needs, from the perspective of the basic theory of NMR, using computer simulation tissue signals, measuring experimental phantom and using analysis method to separate the image signal of fat and water. In this study, we simulated tissue signal and using the least squares method and independent component analysis method to analysis the MRI results of experimental phantom. The results show that using the phase image to analyze the signals on transversal plane makes the signal oscillation caused by resonance frequency shift become more obvious. The imaging results were analyzed by of the least squares method and independent component analysis method to determine the populations of fat and water. Using independent component analysis can separate images of water and fat clearly and obtained the more accurate signals percentage of fat and water.

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Dissertations / Theses on the topic 'Water/fat imaging'

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