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Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to generate images of the organs in the body. MRI does not involve X-rays or the use of ionizing radiation, which distinguishes it from CT and PET scans. MRI is a medical application of nuclear magnetic resonance (NMR) which can also be used for imaging in other NMR applications, such as NMR spectroscopy.
Multispectral segmentation is a method for differentiating tissue classes of similar characteristics in a single imaging modality using several independent images of the same anatomical slice in different modalities. This makes it easier to discriminate between different tissues, as each tissue responds differently to particular pulse sequences.
Jens Frahm is a German biophysicist and physicochemist. He is Research Group Leader of the Biomedical NMR group at the Max Planck Institute (MPI) for Multidisciplinary Sciences in Göttingen, Germany.
Signal enhancement by extravascular water protons, or SEEP, is a contrast mechanism for functional magnetic resonance imaging (fMRI), which is an alternative to the more commonly employed BOLD contrast. This mechanism for image contrast changes corresponding to changes in neuronal activity was first proposed by Dr. Patrick Stroman in 2001. SEEP contrast is based on changes in tissue water content which arise from the increased production of extracellular fluid and swelling of neurons and glial cells at sites of neuronal activity. Because the dominant sources of MRI signal in biological tissues are water and lipids, an increase in tissue water content is reflected by a local increase in MR signal intensity. A correspondence between BOLD and SEEP signal changes, and sites of activity, has been observed in the brain and appears to arise from the common dependence on changes in local blood flow to cause a change in blood oxygenation or to produce extracellular fluid. The advantage of SEEP contrast is that it can be detected with MR imaging methods which are relatively insensitive to magnetic susceptibility differences between air, tissues, blood, and bone. Such susceptibility differences can give rise to spatial image distortions and areas of low signal, and magnetic susceptibility changes in blood give rise to the BOLD contrast for fMRI. The primary application of SEEP to date has been fMRI of the spinal cord because the bone/tissue interfaces around the spinal cord cause poor image quality with conventional fMRI methods. The disadvantages of SEEP compared to BOLD contrast are that it reveals more localized areas of activity, and in the brain the signal intensity changes are typically lower, and it can therefore be more difficult to detect.
Susceptibility weighted imaging (SWI), originally called BOLD venographic imaging, is an MRI sequence that is exquisitely sensitive to venous blood, hemorrhage and iron storage. SWI uses a fully flow compensated, long echo, gradient recalled echo (GRE) pulse sequence to acquire images. This method exploits the susceptibility differences between tissues and uses the phase image to detect these differences. The magnitude and phase data are combined to produce an enhanced contrast magnitude image. The imaging of venous blood with SWI is a blood-oxygen-level dependent (BOLD) technique which is why it was referred to as BOLD venography. Due to its sensitivity to venous blood SWI is commonly used in traumatic brain injuries (TBI) and for high resolution brain venographies but has many other clinical applications. SWI is offered as a clinical package by Philips and Siemens but can be run on any manufacturer’s machine at field strengths of 1.0 T, 1.5 T, 3.0 T and higher.
Jemris is an open source MRI sequence design and simulation framework written in C++.
William A. EdelsteinFInstP was an American physicist. One of the key developers of magnetic resonance imaging (MRI), he was part of the team that developed the first full-body MRI scanner at the University of Aberdeen, Scotland, and was the primary inventor of spin-warp imaging, which is still used in all commercial MRI systems.
Real-time magnetic resonance imaging (MRI) refers to the continuous monitoring ("filming") of moving objects in real time. Because MRI is based on time-consuming scanning of k-space, real-time MRI was possible only with low image quality or low temporal resolution. Using an iterative reconstruction algorithm these limitations have recently been removed: a new method for real-time MRI achieves a temporal resolution of 20 to 30 milliseconds for images with an in-plane resolution of 1.5 to 2.0 mm. Real-time MRI promises to add important information about diseases of the joints and the heart. In many cases MRI examinations may become easier and more comfortable for patients.
Christopher J. Hardy is an American physicist and inventor of several magnetic resonance imaging (MRI) subsystem technologies for use in real time MRI and cardiac MR imaging and spectroscopy.
Harmonic phase (HARP) algorithm is a medical image analysis technique capable of extracting and processing motion information from tagged magnetic resonance image (MRI) sequences. It was initially developed by N. F. Osman and J. L. Prince at the Image Analysis and Communications Laboratory at Johns Hopkins University. The method uses spectral peaks in the Fourier domain of tagged MRI, calculating the phase images of their inverse Fourier transforms, which are called harmonic phase (HARP) images. The motion of material points through time is then tracked, under the assumption that the HARP value of a fixed material point is time-invariant. The method is fast and accurate, and has been accepted as one of the most popular tagged MRI analysis methods in medical image processing.
Nadine Barrie Smith (1962–2010) was an American biomedical researcher in the field of therapeutic ultrasound and non-invasive drug delivery. She was also an educator and mentor, especially to women students.
Jürgen Klaus Hennig is a German chemist and medical physicist. Internationally he is considered to be one of the pioneers of Magnetic Resonance Imaging for clinical diagnostics. He is the Scientific Director of the Department of Diagnostic Radiology and Chairman of the Magnetic Resonance Development and Application Center (MRDAC) at the University Medical Center Freiburg. In the year 2003 he was awarded the Max Planck Research Award in the category of Biosciences and Medicine.
Functional magnetic resonance spectroscopy of the brain (fMRS) uses magnetic resonance imaging (MRI) to study brain metabolism during brain activation. The data generated by fMRS usually shows spectra of resonances, instead of a brain image, as with MRI. The area under peaks in the spectrum represents relative concentrations of metabolites.
Val Murray Runge is an American and Swiss professor of radiology and the editor-in-chief of Investigative Radiology. Runge was one of the early researchers to investigate the use of gadolinium-based contrast agents for magnetic resonance imaging (MRI), giving the first presentation in this field, followed two years later by the first presentation of efficacy. His research also pioneered many early innovations in MRI, including the use of tilted planes and respiratory gating. His publication on multiple sclerosis in 1984 represented the third and largest clinical series investigating the role of MRI in this disease, and the first to show characteristic abnormalities on MRI in patients whose CT was negative.
Gel dosimeters, also called Fricke gel dosimeters, are manufactured from radiation sensitive chemicals that, upon irradiation with ionising radiation, undergo a fundamental change in their properties as a function of the absorbed radiation dose.
Ferenc Andras Jolesz was a Hungarian-American physician and scientist best known for his research on image guided therapy, the process by which information derived from diagnostic imaging is used to improve the localization and targeting of diseased tissue to monitor and control treatment during surgical and interventional procedures. He pioneered the field of Magnetic Resonance Imaging-guided interventions and introduced of a variety of new medical procedures based on novel combinations of imaging and therapy delivery.
James S. Hyde is an American biophysicist. He holds the James S. Hyde chair in Biophysics at the Medical College of Wisconsin (MCW) where he specializes in magnetic resonance instrumentation and methodology development in two distinct areas: electron paramagnetic resonance (EPR) spectroscopy and magnetic resonance imaging (MRI). He is senior author of the widely cited 1995 paper by B.B. Biswal et al. reporting the discovery of resting state functional connectivity (fcMRI) in the human brain. He also serves as Director of the National Biomedical EPR Center, a Research Resource supported by the National Institutes of Health. He is author or more than 400 peer-reviewed papers and review articles and holds 35 U.S. Patents. He has been recognized by Festschrifts in both EPR and fcMRI.
The history of magnetic resonance imaging (MRI) includes the work of many researchers who contributed to the discovery of nuclear magnetic resonance (NMR) and described the underlying physics of magnetic resonance imaging, starting early in the twentieth century. MR imaging was invented by Paul C. Lauterbur who developed a mechanism to encode spatial information into an NMR signal using magnetic field gradients in September 1971; he published the theory behind it in March 1973. The factors leading to image contrast had been described nearly 20 years earlier by physician and scientist Erik Odeblad and Gunnar Lindström. Among many other researchers in the late 1970s and 1980s, Peter Mansfield further refined the techniques used in MR image acquisition and processing, and in 2003 he and Lauterbur were awarded the Nobel Prize in Physiology or Medicine for their contributions to the development of MRI. The first clinical MRI scanners were installed in the early 1980s and significant development of the technology followed in the decades since, leading to its widespread use in medicine today.
Jonathan S. Lewin is an American neuroradiologist specializing in medical imaging research with an emphasis on the investigation, development, and translation of new magnetic resonance imaging (MRI) techniques. He serves as executive vice president for health affairs (EVPHA) for Emory University, executive director of the Woodruff Health Sciences Center, and CEO and chairman of the board of Emory Healthcare. He is also professor of both radiology and imaging sciences and of biomedical engineering in the Emory School of Medicine and professor of health policy and management in the Rollins School of Public Health.
Denis Le Bihan is a medical doctor, physicist, member of the Institut de France, member of the French Academy of Technologies and director since 2007 of NeuroSpin, an institution of the Atomic Energy and Alternative Energy Commission (CEA) in Saclay, dedicated to the study of the brain by magnetic resonance imaging (MRI) with a very high magnetic field. Denis Le Bihan has received international recognition for his outstanding work, introducing new imaging methods, particularly for the study of the human brain, as evidenced by the many international awards he has received, such as the Gold Medal of the International Society of Magnetic Resonance in Medicine (2001), the coveted Lounsbery Prize, the Louis D. Prize from the Institut de France and the prestigious Honda Prize (2012). His work has focused on the introduction, development and application of highly innovative methods, notably diffusion MRI.
References
- ↑ "Archived copy" (PDF). Archived from the original (PDF) on 4 July 2010. Retrieved 20 May 2012.
{{cite web}}: CS1 maint: archived copy as title (link) - ↑ "Archived copy". Archived from the original on 4 March 2016. Retrieved 19 May 2012.
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