Magnetic Resonance Imaging
Magnetic Resonance Imaging - Related Videos
11:37
Cardiac Magnetic Resonance Imaging
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2023
Source: Frederick W. Damen and Craig J. Goergen, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana In this video, high field, small-bore magnetic resonance imaging (MRI) with physiological monitoring is demonstrated to acquire gated cine loops of the murine cardiovascular system. This procedure provides a basis for assessing left-ventricular function, visualizing vascular networks, and quantifying motion of organs due to respiration. Comparable small animal...
09:08
Multiple-mouse Neuroanatomical Magnetic Resonance Imaging
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Cited by 59 •
2011
Magnetic resonance imaging (MRI) has become an increasingly popular tool for examining the phenotype of genetically altered mice. This article illustrates the methods necessary to achieve high-throughput phenotyping of genetically altered mice using multiple-mouse MRI.
07:33
Quantifying Mixing using Magnetic Resonance Imaging
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Cited by 5 •
2012
Magnetic resonance imaging (MRI) provides a powerful tool to evaluate the effectiveness of process equipment during operation. We discuss the use of MRI to visualize mixing in a static mixer. The application is relevant to personal care products, but can be applied to a broad range of food, chemical, biomass and biological fluids.
09:15
fMRI: Functional Magnetic Resonance Imaging
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2023
Functional magnetic resonance imaging (fMRI) is a non-invasive neuroimaging technique used to investigate human brain function and cognition in both healthy individuals and populations with abnormal brain states. Functional MRI utilizes a magnetic resonance signal to detect changes in blood flow that are coupled to neuronal activation when a specific task is performed. This is possible because hemoglobin within the blood has different magnetic properties depending on whether or not it is bound...
11:27
Magnetically-Assisted Remote Controlled Microcatheter Tip Deflection under Magnetic Resonance Imaging
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Cited by 10 •
2013
Current applied to an endovascular microcatheter with microcoil tip made by laser lathe lithography can achieve controllable deflections under magnetic resonance (MR) guidance, which may improve speed and efficacy of navigation of vasculature during various endovascular procedures.
FAQs
After a radiofrequency pulse changes nuclear alignment, hydrogen nuclei return toward equilibrium at characteristic rates. These relaxation signals vary with the surrounding tissue and with the timing of measurements, allowing tissues with different composition to produce different signal intensities. Researchers can therefore distinguish biological structures and tissue changes without relying on a single uniform image contrast.
Magnetic-field gradients impose controlled spatial differences on the detected resonance signals. These differences allow the system to determine where signals originated and to organize them into an image. Without spatial encoding, the measured relaxation response would not identify the location of a structure, limiting the ability to map organs, tissues, or disease-related changes.
Different pulse sequences alter how radiofrequency excitation, signal detection, and relaxation timing are combined. As a result, one acquisition can emphasize anatomical organization, whereas another can make tissue composition, blood flow, or functional changes more apparent. Selecting the sequence and contrast therefore determines which biological property receives the strongest visual emphasis.
Hydrogen provides a strong source of measurable signal because it is abundant in biological water and fat. Its distribution gives MRI broad access to internal anatomy and tissue composition. This emphasis on hydrogen also supports noninvasive biological studies without ionizing radiation, making the technique useful for examining structures and disease-related changes.
An acquisition begins by placing the subject in a strong magnetic field, followed by radiofrequency excitation that disturbs nuclear alignment. The returning relaxation signals are then detected while magnetic-field gradients provide spatial information. The collected signals are used to form images, with pulse-sequence choices determining which anatomical or biological features are emphasized.
Researchers choose MRI when they need detailed, noninvasive views of internal biological organization. It can support studies of the brain, organs, and tissues, as well as investigations of disease-related changes. Because variations in imaging sequences can reveal anatomy, tissue composition, blood flow, and function, the method accommodates both structural and broader biological questions.