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Magnetic resonance angiography (MRA) is a group of techniques based on magnetic resonance imaging (MRI) to image blood vessels. Magnetic resonance angiography is used to generate images of arteries (and less commonly veins) in order to evaluate them for stenosis (abnormal narrowing), occlusions, aneurysms (vessel wall dilatations, at risk of rupture) or other abnormalities.
Magnetic resonance angiography (MRA) and venography: Time-of-flight: TOF: Blood entering the imaged area is not yet magnetically saturated, giving it a much higher signal when using short echo time and flow compensation. Detection of aneurysm, stenosis, or dissection [94] Phase-contrast magnetic resonance imaging: PC-MRA
T 1-weighted images, left image without, right image with contrast medium administration. Gadolinium(III) containing MRI contrast agents (often termed simply "gado" or "gad") are the most commonly used for enhancement of vessels in MR angiography or for brain tumor enhancement associated with the degradation of the blood–brain barrier (BBB).
Diffusion-weighted magnetic resonance imaging (DWI or DW-MRI) is the use of specific MRI sequences as well as software that generates images from the resulting data that uses the diffusion of water molecules to generate contrast in MR images.
Magnetic resonance angiography may be performed with or without contrast medium and is used to assess congenital or acquired abnormalities of the coronary arteries and great vessels. [ 9 ] Obstacles to its wider application include limited access to scanners, lack of technologists and skilled clinicians, relatively high costs, and competing ...
SWI is uniquely suited to take advantage of higher field systems, as the contrast in the phase image is linearly proportional to echo time (TE) and field strength. Higher fields thus allow shorter echo times without a loss of contrast which can reduce scan time and motion related artifacts.
MRI without contrast agents is the imaging mode of choice for pre-surgical, in-utero diagnosis and evaluation of fetal tumors, primarily teratomas, facilitating open fetal surgery, other fetal interventions, and planning for procedures (such as the EXIT procedure) to safely deliver and treat babies whose defects would otherwise be fatal. [52] [53]
The concentration of the contrast agent is measured as it passes from the blood vessels to the extracellular space of the tissue (it does not pass the membranes of cells) and as it goes back to the blood vessels. [5] [6] The contrast agents used for DCE-MRI are often gadolinium based. Interaction with the gadolinium (Gd) contrast agent ...