Home About us Contact
|
Home About us Contact | ||
|
|
||
Imaging Methods (imaging + methods)
Kinds of Imaging Methods Selected AbstractsINVESTIGATION OF THE CONTENT OF ANCIENT TIBETAN METALLIC BUDDHA STATUES BY MEANS OF NEUTRON IMAGING METHODSARCHAEOMETRY, Issue 3 2010E. H. LEHMANN Many important cultural and religious objects from Asia consist of outer metallic shapes, usually bronze, which fully enclose inner contents made of organic materials such as wood, bark, paper, textile, plants and others. Bronze and other metallic materials, such as copper and silver, are generally more transparent to neutrons than to X-rays. However, organic materials are less transparent to neutrons than to X-rays and therefore organic materials, enclosed by metallic materials, can be made visible with neutrons. Therefore, neutron imaging (radiography and tomography) was found to be an ideal tool for the inspection of objects that consist of metal outside and organic materials inside. This has been successfully demonstrated here with four metallic Tibetan Buddha statues, providing archaeometry with a powerful new tool. The first successful applications of this novel technique are described in this article. Further possible and useful applications of neutron imaging of cultural objects are outlined. [source] Imaging methods in periodontologyPERIODONTOLOGY 2000, Issue 1 2004André Mol No abstract is available for this article. [source] Imaging of the lymphatic system: new horizons,CONTRAST MEDIA & MOLECULAR IMAGING, Issue 6 2006Tristan Barrett Abstract The lymphatic system is a complex network of lymph vessels, lymphatic organs and lymph nodes. Traditionally, imaging of the lymphatic system has been based on conventional imaging methods like computed tomography (CT) and magnetic resonance imaging (MRI), whereby enlargement of lymph nodes is considered the primary diagnostic criterion for disease. This is particularly true in oncology, where nodal enlargement can be indicative of nodal metastases or lymphoma. CT and MRI on their own are, however, anatomical imaging methods. Newer imaging methods such as positron emission tomography (PET), dynamic contrast-enhanced MRI (DCE-MRI) and color Doppler ultrasound (CDUS) provide a functional assessment of node status. None of these techniques is capable of detecting flow within the lymphatics and, thus, several intra-lymphatic imaging methods have been developed. Direct lymphangiography is an all-but-extinct method of visualizing the lymphatic drainage from an extremity using oil-based iodine contrast agents. More recently, interstitially injected intra-lymphatic imaging, such as lymphoscintigraphy, has been used for lymphedema assessment and sentinel node detection. Nevertheless, radionuclide-based imaging has the disadvantage of poor resolution. This has lead to the development of novel systemic and interstitial imaging techniques which are minimally invasive and have the potential to provide both structural and functional information; this is a particular advantage for cancer imaging, where anatomical depiction alone often provides insufficient information. At present the respective role each modality plays remains to be determined. Indeed, multi-modal imaging may be more appropriate for certain lymphatic disorders. The field of lymphatic imaging is ever evolving, and technological advances, combined with the development of new contrast agents, continue to improve diagnostic accuracy. Published in 2006 by John Wiley & Sons, Ltd. [source] Actin-like protein 1 (ALP1) is a component of dynamic, high molecular weight complexes in Toxoplasma gondii,CYTOSKELETON, Issue 1 2010Jennifer L. Gordon Abstract Apicomplexan parasites, such as Toxoplasma gondii, rely on actin-based motility for cell invasion, yet conventional actin does not appear to be required for cell division in these parasites. Apicomplexans also contain a variety of actin-related proteins (Arps); however, most of these not directly orthologous to Arps in well-studied systems. We recently identified an apicomplexan-specific member of this family called Actin-Like Protein 1, (ALP1), which plays a role in the assembly of vesicular components recruited to the inner membrane complex (IMC) of daughter cells during cell division. In addition to its enrichment at daughter cell membranes, ALP1 is localized throughout the cytoplasm both diffusely distributed and concentrated in clusters that are detected by fluorescence microscopy, suggesting it forms complexes. Using quantitative optical imaging methods, including fluorescence recovery after photobleaching (FRAP) and fluorescence loss in photobleaching (FLIP), we demonstrated that ALP1 is a component of a large complex, and that it readily exchanges between diffusible and complex-bound forms. Sedimentation and density gradient analyses revealed that ALP1 is found in a freely soluble state as well as high molecular weight complexes. During cell division, ALP1 was dynamically associated with the IMC, suggesting it rapidly cycles between freely diffusible and complex forms during daughter cell assembly. © 2009 Wiley-Liss, Inc. [source] Advanced microscopic imaging methods to investigate cortical development and the etiology of mental retardationDEVELOPMENTAL DISABILITIES RESEARCH REVIEW, Issue 4 2005Tarik F. Haydar Abstract Studies on human patients and animal models of disease have shown that disruptions in prenatal and early postnatal brain development are a root cause of mental retardation. Since proper brain development is achieved by a strict spatiotemporal control of neurogenesis, cell migration, and patterning of synapses, abnormalities in one or more of these events during prenatal development can lead to cognitive dysfunction after birth. Many of underlying causes of mental retardation must therefore be studied in developing brains. To aid in this research, live imaging using laser scanning microscopy (LSM) has recently allowed neuroscientists to delve deeply into the complex three-dimensional environment of the living brain to record dynamic cellular events over time. This review will highlight recent examples of how LSM is being applied to elucidate both normal and abnormal cortical development. © 2005 Wiley-Liss, Inc. MRDD Research Reviews 2005;11:303,316. [source] MR imaging methods for assessing fetal brain developmentDEVELOPMENTAL NEUROBIOLOGY, Issue 6 2008Mary Rutherford Abstract Fetal magnetic resonance imaging provides an ideal tool for investigating growth and development of the brain in vivo. Current imaging methods have been hampered by fetal motion but recent advances in image acquisition can produce high signal to noise, high resolution 3-dimensional datasets suitable for objective quantification by state of the art post acquisition computer programs. Continuing development of imaging techniques will allow a unique insight into the developing brain, more specifically process of cell migration, axonal pathway formation, and cortical maturation. Accurate quantification of these developmental processes in the normal fetus will allow us to identify subtle deviations from normal during the second and third trimester of pregnancy either in the compromised fetus or in infants born prematurely. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008 [source] Magnetic resonance imaging features of an extranodal T cell rich B cell lymphoma in the pharyngeal mucosa in a horseEQUINE VETERINARY EDUCATION, Issue 6 2008V. Jakesova Summary An 11-year-old Warmblood gelding was presented for inspiratory stridor and dysphagia. Based on history and clinical examination, a solitary mass localised in the oropharynx was suspected. Due to its inaccessibility and defensive behaviour of the horse, it was difficult to visualise this mass either by upper airway endoscopy or by oral examination and the conventional imaging methods (radiology and ultrasound) provided only limited information. Fine needle aspiration cytology was suggestive of lymphoma, but the exact localisation and the extent of tissue infiltration of the tumour could only be defined by magnetic resonance imaging (MRI). MRI has proved to be a very useful diagnostic tool in equine lameness investigation and, as this case illustrates, it has considerable diagnostic potential for soft tissue examination of the equine head. [source] Pathogenesis, detection and treatment of Achilles tendon xanthomasEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 4 2005S. G. Tsouli Abstract Tendon xanthomatosis often accompanies familial hypercholesterolaemia, but it can also occur in other pathologic states. Achilles tendons are the most common sites of tendon xanthomas. Low-density lipoprotein (LDL) derived from the circulation accumulates into tendons. The next steps leading to the formation of Achilles tendon xanthomas (ATX) are the transformation of LDL into oxidized LDL (oxLDL) and the active uptake of oxLDL by macrophages within the tendons. Although physical examination may reveal Achilles tendon xanthomas (ATX), there are several imaging methods for their detection. It is worth mentioning that ultrasonography is the method of choice in everyday clinical practice. Although several treatments for Achilles tendon xanthomas (ATX) have been proposed (LDL apheresis, statins, etc.), they target mostly in the treatment of the basic metabolic disorder of lipid metabolism, which is the main cause of these lesions. In this review we describe the formation, detection, differential diagnosis and treatment of ATX as well as the relationship between tendon xanthomas and atheroma. [source] Pathogen-Mimicking MnO Nanoparticles for Selective Activation of the TLR9 Pathway and Imaging of Cancer Cells,ADVANCED FUNCTIONAL MATERIALS, Issue 23 2009Mohammed Ibrahim Shukoor Abstract Here, design of the first pathogen-mimicking metal oxide nanoparticles with the ability to enter cancer cells and to selectively target and activate the TLR9 pathway, and with optical and MR imaging capabilities, is reported. The immobilization of ssDNA (CpG ODN 2006) on MnO nanoparticles is performed via the phosphoramidite route using a multifunctional polymer. The multifunctional polymer used for the nanoparticle surface modification not only affords a protective organic biocompatible shell but also provides an efficient and convenient means for loading immunostimulatory oligonucleotides. Since fluorescent molecules are amenable to photodetection, a chromophore (Rhodamine) is introduced into the polymer chain to trace the nanoparticles in Caki-1 (human kidney cancer) cells. The ssDNA coupled nanoparticles are used to target Toll-like receptors 9 (TLR9) receptors inside the cells and to activate the classical TLR cascade. The presence of TLR9 is demonstrated independently in the Caki-1 cell line by western blotting and immunostaining techniques. The magnetic properties of the MnO core make functionalized MnO nanoparticles potential diagnostic agents for magnetic resonance imaging (MRI) thereby enabling multimodal detection by a combination of MR and optical imaging methods. The trimodal nanoparticles allow the imaging of cellular trafficking by different means and simultaneously are an effective drug carrier system. [source] Diagnostic evaluation of cystic pancreatic lesionsHPB, Issue 1 2008B. C. VISSER Abstract Background. Cystic pancreatic neoplasms (CPNs) present a unique challenge in preoperative diagnosis. We investigated the accuracy of diagnostic methods for CPN. Material and methods. This retrospective cases series includes 70 patients who underwent surgery at a university hospital for presumed CPNs between 1997 and 2003, and for whom a definitive diagnosis was established. Variables examined included symptoms, preoperative work-up (including endoscopic retrograde cholangiopancreatography (ERCP) in 22 cases and endoscopic ultrasound (EUS) in 12), and operative and pathological findings. Preoperative computed tomography (CT) and magnetic resonance imaging (MRI) scans (n=50 patients; CT=48; MRI=13) were independently reviewed by two blinded GI radiologists. Results. The final histopathologic diagnoses were mucinous cystic neoplasm (n=13), mucinous cystadenocarcinoma (10), serous cystadenoma (11), IPMN (14), simple cyst (3), cystic neuroendocrine tumor (5), pseudocyst (4), and other (10). Overall, 25 of 70 were malignant (37%), 21 premalignant (30%), and 24 benign (34%). The attending surgeon's preoperative diagnosis was correct in 31% of cases, incorrect in 29%, non-specific "cystic tumor" in 27%, and "pseuodcyst vs. neoplasm" in 11%. Eight had been previously managed as pseudocysts, and 3 pseudocysts were excised as presumed CPN. In review of the CT and MRI, a multivariate analysis of the morphologic features did not identify predictors of specific pathologic diagnoses. Both radiologists were accurate with their preferred (no. 1) diagnosis in <50% of cases. MRI demonstrated no additional utility beyond CT. Conclusions. The diagnosis of CPN remains challenging. Cross-sectional imaging methods do not reliably give an accurate preoperative diagnosis. Surgeons should continue to err on the side of resection. [source] Comparison of neuronal and hemodynamic measures of the brain response to visual stimulation: An optical imaging studyHUMAN BRAIN MAPPING, Issue 1 2001Gabriele Gratton Abstract The noninvasive mapping of hemodynamic brain activity has led to significant advances in neuroimaging. This approach is based in part on the assumption that hemodynamic changes are proportional to (and therefore constitute a linear measure of) neuronal activity. We report a study investigating the quantitative relationship between neuronal and hemodynamic measures. This study exploited the fact that optical imaging methods can simultaneously provide noninvasive measures of neuronal and hemodynamic activity from the same region of the brain. We manipulated visual stimulation frequency and measured responses from the medial occipital area of 8 young adults. The results were consistent with a model postulating a linear relationship between the neuronal activity integrated over time and the amplitude of the hemodynamic response. The hemodynamic response colocalized with the neuronal response. These data support the use of quantitative neuroimaging methods to infer the intensity and localization of neuronal activity in occipital areas. Hum. Brain Mapping 13:13,25, 2001. © 2001 Wiley-Liss, Inc. [source] Dynamic organization of lymphocyte plasma membrane: lessons from advanced imaging methodsIMMUNOLOGY, Issue 1 2010Dylan M. Owen Summary Lipids and lipid domains are suggested to play an essential role in the heterogeneous organization of the plasma membrane in eukaryotic cells, including cells of the immune system. We summarize the results of advanced imaging and physical studies of membrane organization with special focus on the plasma membrane of lymphocytes. We provide a comprehensive up-to-date view on the existence of membrane lipid and protein clusters such as lipid rafts and suggest research directions to better understand these highly dynamic entities on the surface of immune cells. [source] Incidentally discovered pheochromocytoma in long-term hemodialysis patientsINTERNATIONAL JOURNAL OF UROLOGY, Issue 12 2002MASAAKI MORIOKA Abstract Two cases of pheochromocytoma incidentally discovered in long-term hemodialysis patients are reported. Case 1 was a 47-year-old-man who had been receiving hemodialysis for 18 years. Case 2 was a 33-year-old woman who had been receiving hemodialysis for 12 years. Both cases were normotensive, and no specific symptoms suggesting pheochromocytoma were seen. Plasma norepinephrine (NE) levels were not elevated in both cases; however, the level of epinephrine (E) was double the normal range in Case 2. After surgery, plasma E level returned to the normal range in Case 2; however, the level of NE remained almost the same as the preoperative value in both cases. Plasma catecolamine levels in long-term hemodialysis patients with pheochromocytoma are reviewed in the present report, and the efficacy of imaging methods in the diagnosis of pheochromocytoma are discussed. [source] Understanding immune cell trafficking patterns via in vivo bioluminescence imagingJOURNAL OF CELLULAR BIOCHEMISTRY, Issue S39 2002Stefanie Mandl Abstract Cell migration is a key aspect of the development of the immune system and mediating an immune response. There is extensive and continual redistribution of cells to different anatomic sites throughout the body. These trafficking patterns control immune function, tissue regeneration, and host responses to insult. The ability to monitor the fate and function of cells, therefore, is imperative to both understanding the role of specific cells in disease processes and to devising rational therapeutic strategies. Determining the fate of immune cells and understanding the functional changes associated with migration and proliferation require effective means of obtaining in vivo measurements in the context of intact organ systems. A variety of imaging methods are available to provide structural information, such as X-ray CT and MRI, but only recently new tools have been developed that reveal cellular and molecular changes as they occur within living animals. We have pioneered one of these techniques that is based on the observations that light passes through mammalian tissues, and that luciferases can serve as internal biological sources of light in the living body. This method, called in vivo bioluminescence imaging, is a rapid and noninvasive functional imaging method that employs light-emitting reporters and external photon detection to follow biological processes in living animals in real time. This imaging strategy enables the studies of trafficking patterns for a variety of cell types in live animal models of human biology and disease. Using this approach we have elucidated the spatiotemporal trafficking patterns of lymphocytes within the body. In models of autoimmune disease we have used the migration of "pathogenic" immune cells to diseased tissues as a means to locally deliver and express therapeutic proteins. Similarly, we have determined the tempo of NK-T cell migration to neoplastic lesions and measured their life span in vivo. Using bioluminescence imaging individual groups of animals can be followed over time significantly reducing the number of animals per experiment, and improving the statistical significance of a study since changes in a given population can be studied over time. Such rapid assays that reveal cell fates in vivo will increase our basic understanding of the molecular signals that control these migratory pathways and will substantially speed up the development and evaluation of therapies. J. Cell. Biochem. Suppl. 39: 239,248, 2002. © 2002 Wiley-Liss, Inc. [source] Role of neuroimaging in promoting long-term recovery from ischemic strokeJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2010Rüdiger J. Seitz MD Abstract Human ischemic stroke is an acute disorder followed by a recovery period which may be of varying duration and mechanism. Imaging has created a means to explore the stroke process in vivo, particularly its underlying pathophysiology and recovery mechanisms. Evidence from multicenter studies has shown that, in the acute phase, arterial recanalization and reperfusion of ischemic brain tissue are the most important determinants of recovery. This is followed by functional and structural changes in the perilesional tissue and in large-scale bihemispheric networks that continue with different dynamics for weeks to months. Proof-of-principle studies have revealed that the behavioral gains induced by rehabilitation are paralleled by changes in functional representations. This is supported by data from neuroimaging and electrophysiological studies early after stroke which have shown that dedicated training can induce changes in cerebral functional representations. Accordingly, there is clear evidence that neuroimaging has a significant potential for monitoring the hemodynamic, functional, and structural factors determining recovery from stroke. New imaging methods may provide relevant biomarkers for treatment decisions and therapeutic monitoring. By combining neuroimaging with electrophysiological measures, opportunities exist to develop neuroscience-based strategies in rehabilitation. J. Magn. Reson. Imaging 2010;32:756,772. © 2010 Wiley-Liss, Inc. [source] Imaging biomarkers of cardiovascular diseaseJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 3 2010Jinnan Wang PhD Abstract Cardiovascular disease (CVD) is a leading cause of morbidity and mortality worldwide. Current clinical techniques that rely on stenosis measurement alone appear to be insufficient for risk prediction in atherosclerosis patients. Many novel imaging methods have been developed to study atherosclerosis progression and to identify new features that can predict future clinical risk. MRI of atherosclerotic vessel walls is one such method. It has the ability to noninvasively evaluate multiple biomarkers of the disease such as luminal stenosis, plaque burden, tissue composition and plaque activity. In addition, the accuracy of in vivo MRI has been validated against histology with high reproducibility, thus paving the way for application to epidemiological studies of disease pathogenesis and, by serial MRI, in monitoring the efficacy of therapeutic intervention. In this review, we describe the various MR techniques used to evaluate aspects of plaque progression, discuss imaging-based measurements (imaging biomarkers), and also detail their validation. The application of plaque MRI in clinical trials as well as emerging imaging techniques used to evaluate plaque compositional features and biological activities are also discussed. J. Magn. Reson. Imaging 2010;32:502,515. © 2010 Wiley-Liss, Inc. [source] Initial feasibility of a multi-station high resolution three-dimensional dark blood angiography protocol for the assessment of peripheral arterial diseaseJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2009Georgeta Mihai PhD Abstract Purpose To evaluate the feasibility of a multi-station three dimensional (3D) T1-weighted turbo spin echo (TSE) dark-blood Sampling Perfection with Application optimized Contrasts using different flip angle Evolution sequence (T1w-SPACE), to assess aorta, iliac, and superficial femoral (SFA) arteries (inflow vessels) by comparing it with a multi-station contrast enhanced MR angiography (CE-MRA) with identical resolution. Materials and Methods A total of 6 volunteers and 14 peripheral arterial disease (PAD) patients were included in the study. Abdominal and thigh T1w-SPACE and lower leg time-resolved MRA (TR-MRA) with low dose contrast were followed by 3-station CE-MRA. Quantitative measurements of lumen area at 17 locations from T1w-SPACE and CE-MRA were obtained. Additionally, vessel wall areas at the same locations were obtained from the T1w-SPACE images. Results Quantitative comparison of lumen areas with T1w-SPACE and CE-MRA revealed strong correlation between the two techniques and strong inter-observer agreement for each of the two imaging methods (r > 0.9; P < 0.001). Localized vessel wall area measurements obtained in PAD patients were significantly greater compared with those obtained in normal volunteers (mean difference 43.75 ± 12.46 mm2; P < 0.001). Stenosis severity obtained from T1w-SPACE localized measurements showed significant arterial area stenosis in PAD patients. Conclusion T1w-SPACE imaging of inflow vessels is feasible, and in addition to CE-MRA has the ability to assess atherosclerotic plaque and vascular remodeling. J. Magn. Reson. Imaging 2009;30:785,793. © 2009 Wiley-Liss, Inc. [source] Comparison between 2D and 3D high-resolution black-blood techniques for carotid artery wall imaging in clinically significant atherosclerosisJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2008Niranjan Balu PhD Abstract Purpose To compare two- (2D) and three-dimensional (3D) black-blood imaging methods for morphological measurements of the carotid artery wall and atherosclerotic plaque. Materials and Methods A total of 18 subjects with 50% to 79% carotid stenosis were scanned with 2D (2-mm slice thickness) and 3D (1-mm/0.5-mm actual/interpolated slice thickness) T1-weighted fast spin-echo (FSE) black-blood imaging sequences with double inversion-recovery (DIR) blood suppression. Morphological measurements (lumen area, wall area, vessel area, mean wall thickness, and maximal wall thickness), signal-to-noise ratio (SNR) in the wall and lumen, and wall-lumen contrast-to-noise ratio (CNR) were compared between 2D and 3D images. The effect of improved slice resolution in 3D imaging was evaluated for visualization of small plaque components. Results Lumen SNR (P = 0.16), wall SNR (P = 0.65), and CNR (P = 0.94) were comparable between 2D/3D. There was no difference in average lumen area (P = 0.16), average wall area (P = 0.99), average vessel area (P = 0.0.58), mean wall thickness (P = 0.09), and maximum wall thickness (P = 0.06) between 2D/3D. Distributions of small plaque components such as calcification were better characterized by the 3D acquisition. There was a higher sensitivity to motion artifacts with 3D imaging, resulting in three examinations with low image quality. Conclusion 2D and 3D protocols provided comparable morphometric measurements of the carotid artery. The major advantage of 3D imaging is improved small plaque component visualization, while the 2D technique provides higher reliability for image quality. J. Magn. Reson. Imaging 2008;27:918,924. © 2008 Wiley-Liss, Inc. [source] Parallel imaging of knee cartilage at 3 TeslaJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2007Jin Zuo PhD Abstract Purpose To evaluate the feasibility and reproducibility of quantitative cartilage imaging with parallel imaging at 3T and to determine the impact of the acceleration factor (AF) on morphological and relaxation measurements. Materials and Methods An eight-channel phased-array knee coil was employed for conventional and parallel imaging on a 3T scanner. The imaging protocol consisted of a T2-weighted fast spin echo (FSE), a 3D-spoiled gradient echo (SPGR), a custom 3D-SPGR T1rho, and a 3D-SPGR T2 sequence. Parallel imaging was performed with an array spatial sensitivity technique (ASSET). The left knees of six healthy volunteers were scanned with both conventional and parallel imaging (AF = 2). Results Morphological parameters and relaxation maps from parallel imaging methods (AF = 2) showed comparable results with conventional method. The intraclass correlation coefficient (ICC) of the two methods for cartilage volume, mean cartilage thickness, T1rho, and T2 were 0.999, 0.977, 0.964, and 0.969, respectively, while demonstrating excellent reproducibility. No significant measurement differences were found when AF reached 3 despite the low signal-to-noise ratio (SNR). Conclusion The study demonstrated that parallel imaging can be applied to current knee cartilage quantification at AF = 2 without degrading measurement accuracy with good reproducibility while effectively reducing scan time. Shorter imaging times can be achieved with higher AF at the cost of SNR. J. Magn. Reson. Imaging 2007;26:1001,1009. © 2007 Wiley-Liss, Inc. [source] Imaging in bronchopulmonary sequestrationJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 1 2009P Abbey Summary Bronchopulmonary sequestration is an uncommon pulmonary disorder characterized by an area of non-functioning abnormal lung tissue, which receives its blood supply from a systemic artery and characteristically has no connection with the tracheobronchial tree. The abnormal lung tissue is located within the visceral pleura of a pulmonary lobe in the intralobar variety, whereas the extralobar form has its own visceral pleura. The venous drainage of the extralobar type is usually into the systemic veins, whereas the intralobar type drains into the pulmonary veins. Radiological imaging plays a vital role in establishing the diagnosis, and even more importantly, in providing to the clinician a vascular roadmap essential for surgical planning. We present here a review of bronchopulmonary sequestration and also discuss the role of various imaging methods in the early diagnosis and management of these cases. [source] Imaging of adenomyomatosis of the gall bladderJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 2 2008H Stunell Summary Adenomyomatosis is a relatively common abnormality of the gall bladder, with a reported incidence of between 2.8 and 5%. Although mainly confined to the adult study group, a number of cases have been reported in the paediatric study group. It is characterized pathologically by excessive proliferation of the surface epithelium and hypertrophy of the muscularis propria of the gall bladder wall, with invagination of the mucosa into the thickened muscularis forming the so-called ,Rokitansky,Aschoff' sinuses. The condition is usually asymptomatic and is often diagnosed as an incidental finding on abdominal imaging. The radiological diagnosis is largely dependent on the visualization of the characteristic Rokitansky,Aschoff sinuses. As the condition is usually asymptomatic, the importance of making a correct diagnosis is to prevent misinterpretation of other gall bladder conditions such as gall bladder cancer, leading to incorrect treatment. In the past, oral cholecystography was the main imaging method used to make this diagnosis. In most institutions, oral cholecystography is no longer carried out, and the diagnosis is now more commonly seen on cross-sectional imaging. In this review article, we describe the manifestations of adenomyomatosis on the various imaging methods, with an emphasis on more modern techniques such as magnetic resonance cholangiopancreatography. A brief section on oral cholecystography to aid readers familiar with this technique in understanding the comparable imaging features on more modern imaging techniques is included. [source] Primary gastrointestinal lymphomas: A radiological,pathological review.JOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 2 2006Part 2: Small intestine Summary Primary lymphoma of the small intestine is a heterogeneous group of diseases reflected in its protean imaging features. This review illustrates the widespread appearances seen on imaging methods (primarily CT and barium studies) with pathological correlation. [source] Measurements by MRI of the settling and packing of solid particles from aqueous suspensionsAICHE JOURNAL, Issue 6 2009Julio Acosta-Cabronero Abstract This study extends the application of existing magnetic resonance imaging methods to measure the settling of solid particles from aqueous suspensions. The acquisition of one-dimensional multiecho projections allowed the direct measurement of initial magnetizations (M0), from which solid volume fractions along the sedimentation column were inferred. For polystyrene beads, it was found that monoexponential curves accurately fitted the transverse relaxation decays. In contrast, for the other four solids investigated (activated carbon, talc, calcium carbonate, and glass beads), the single exponential model did not suffice and additional terms in the fitting function significantly improved the calculation of solid concentrations. Additional information about particle sizes was obtained by comparing volume fractions with the spin,spin relaxation times of the hydrogen protons as a function of the vertical height through the sedimenting suspensions of activated carbon and polystyrene beads. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Phase-contrast X-ray imaging combining free space propagation and Bragg diffractionJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2005Paola Coan The combination of X-ray `propagation-based' and `analyzer-based' phase-contrast imaging with a perfect crystal-analyzer is investigated. The image pattern produced using this `hybrid' imaging technique presents peculiar features that can be interpreted as a mixture of the two independent phase-contrast signals. A quantitative analysis has been performed in terms of signal-to-noise ratio for the three techniques considered in this paper. Results show that in the `hybrid imaging' technique this parameter has a weaker dependence on the angular alignment of the crystal analyser with respect to the `analyser-based' imaging. This pioneering experiment indicates that this hybrid imaging technique might permit simultaneous advantage of the specific features of the two imaging methods to be taken. [source] Magnetic resonance imaging of the skinJOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 8 2010J Stefanowska Abstract A thorough examination of the skin is essential to screen various diseases accurately, evaluate the effectiveness of topically applied drugs and assess the results of dermatological surgeries such as skin grafts. The assessment of skin properties is also crucial in the cosmetics industry, where it is important to evaluate the effects skin care products have on these properties. The simplest and most widely used method of skin evaluation, the ,naked eye' assessment, enables researchers to assess only the skin surface and involves a large amount of inter-observer variability. Thanks to a great progress that has been made in physics, electronics and computer engineering in recent years, sophisticated imaging methods are increasingly available in day-to-day studies. The aim of this review was to present one of these techniques, namely the magnetic resonance imaging (MRI), and to discuss its possible use in skin examination and analysis. We present basic principles of MRI, as well as several interesting applications in the field of dermatology, and discuss the advantages and limitations of this method. [source] Acute pancreatitis in dogsJOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue 4 2003Jennifer L. Holm DVM Abstract Objective: To summarize current information regarding severity assessment, diagnostic imaging, and treatment of human and canine acute pancreatitis (AP). Human-based studies: In humans, scoring systems, advanced imaging methods, and serum markers are used to assess the severity of disease, which allows for optimization of patient management. The extent of pancreatic necrosis and the presence of infected pancreatic necrosis are the most important factors determining the development of multiple organ failure (MOF) and subsequent mortality. Considerable research efforts have focused on the development of inexpensive, easy, and reliable laboratory markers to assess disease severity as early as possible in the course of the disease. The use of prophylactic antibiotics, enteral nutrition, and surgery have been shown to be beneficial in certain patient populations. Veterinary-based studies: The majority of what is currently known about naturally occurring canine AP has been derived from retrospective evaluations. The identification and development of inexpensive and reliable detection kits of key laboratory markers in dogs with AP could dramatically improve our ability to prognosticate and identify patient populations likely to benefit from treatment interventions. Treatment remains largely supportive and future studies evaluating the efficacy of surgery, nutritional support and other treatment modalities are warranted. Data sources: Current human and veterinary literature. Conclusions: Pancreatitis can lead to a life-threatening severe systemic inflammatory condition, resulting in MOF and death in both humans and dogs. Given the similarities in the pathophysiology of AP in both humans and dogs, novel concepts used to assess severity and treat people with AP may be applicable to dogs. [source] A simple method for rectified noise floor suppression: Phase-corrected real data reconstruction with application to diffusion-weighted imagingMAGNETIC RESONANCE IN MEDICINE, Issue 2 2010Douglas E. Prah Abstract Diffusion-weighted MRI is an intrinsically low signal-to-noise ratio application due to the application of diffusion-weighting gradients and the consequent longer echo times. The signal-to-noise ratio worsens with increasing image resolution and diffusion imaging methods that use multiple and higher b-values. At low signal-to-noise ratios, standard magnitude reconstructed diffusion-weighted images are confounded by the existence of a rectified noise floor, producing poor estimates of diffusion metrics. Herein, we present a simple method of rectified noise floor suppression that involves phase correction of the real data. This approach was evaluated for diffusion-weighted imaging data, obtained from ethanol and water phantoms and the brain of a healthy volunteer. The parameter fits from monoexponential, biexponential, and stretched-exponential diffusion models were computed using phase-corrected real data and magnitude data. The results demonstrate that this newly developed simple approach of using phase-corrected real images acts to reduce or even suppress the confounding effects of a rectified noise floor, thereby producing more accurate estimates of diffusion parameters. Magn Reson Med, 2010. © 2010 Wiley-Liss, Inc. [source] Robust estimation of spatially variable noise fieldsMAGNETIC RESONANCE IN MEDICINE, Issue 2 2009Bennett A. Landman Abstract Consideration of spatially variable noise fields is becoming increasingly necessary in MRI given recent innovations in artifact identification and statistically driven image processing. Fast imaging methods enable study of difficult anatomical targets and improve image quality but also increase the spatial variability in the noise field. Traditional analysis techniques have either assumed that the noise is constant across the field of view (or region of interest) or have relied on separate MRI acquisitions to measure the noise field. These methods are either inappropriate for many modern scanning protocols or are overly time-consuming for already lengthy scanning sessions. We propose a new, general framework for estimating spatially variable noise fields from related, but independent MR scans that we call noise field equivalent scans. These heuristic analyses enable robust noise field estimation in the presence of artifacts. Generalization of noise estimators based on uniform regions, difference images, and maximum likelihood are presented and compared with the estimators derived from the proposed framework. Simulations of diffusion tensor imaging and T2 -relaxometry demonstrate a 10-fold reduction in mean squared error in noise field estimation, and these improvements are shown to be robust to artifact contamination. In vivo studies show that spatially variable noise fields can be readily estimated with typical data acquired at 1.5T. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source] On the timing characteristics of the apparent diffusion coefficient contrast in fMRIMAGNETIC RESONANCE IN MEDICINE, Issue 2 2002Stacey L. Gangstead Abstract For the past 10 years, functional MRI (fMRI) has seen rapid progress in both clinical and basic science research. Most of the imaging techniques are based on the blood oxygenation level-dependent (BOLD) contrast which arises from the field perturbation of the paramagnetic deoxyhemoglobin due to the mismatch between the local oxygen demand and delivery. Because the changes of oxygenation level take place mostly in the veins, the dominant signal sources of the BOLD signal are intra- and extravascular proton pools of the veins. Perfusion imaging methods, developed parallel to the BOLD technique, seek to quantify the blood flow and perfusion. Recently, perfusion imaging using arterial spin tagging methods have been used to study brain function by investigating the changes of the blood flow and perfusion during brain activation, thereby generating an alternative contrast mechanism to the functional brain imaging. Since most of these methods require tagging pulse and wait time for blood to be delivered to the imaged slice, the temporal resolution may not be optimal. Dynamic intravoxel incoherent motion (IVIM) weighting schemes using apparent diffusion coefficient (ADC) contrast were suggested to image the relative changes of the in-plane blood flow during brain function. In this report, it was demonstrated that, in addition to the spatial discrepancies of the activated areas, the time course based on the ADC contrast consistently precedes that from the BOLD contrast with timing offset on the order of 1 sec. Since arterial networks would have different spatial locations and preceding temporal characters, the findings in this report are indicative that the ADC contrast is sensitive to the arterial blood flow changes. Magn Reson Med 48:385,388, 2002. © 2002 Wiley-Liss, Inc. [source] LO Peg in 1998: star-spot patterns and differential rotationMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2005J. R. Barnes ABSTRACT We present Doppler images of the young K5V,K7V rapid rotator LO Peg from seven nights of continuous spectroscopy obtained in 1998 from July 04 to July 10. The images reveal the presence of a strong polar cap with appendages extending to mid-latitudes, but no star-spots are seen below 15°. We briefly discuss the distribution of spots in light of recent flux transport simulations, which are able to reproduce the observed latitude dependence. With the full time series of spectra, of which 314 are useful, many phases are observed three times over the seven nights of observations. Using star-spots as tracers of a solar-like latitudinal differential rotation in our image reconstructions, we find that the equatorial regions complete one more rotation than the polar regions every 181 ± 35 d. LO Peg is the second coolest star for which such a measurement has been made using indirect imaging methods. The degree of latitudinal shear is less than that seen in G and early K dwarfs, suggesting a trend in which differential rotation decreases with stellar mass in (pre-)main-sequence objects. [source] | ||||||||||||||||||||||||||||||||||||||||