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The key to Phase-contrast MRI (PC-MRI) is the use of a bipolar gradient. [4] A bipolar gradient has equal positive and negative magnitudes that are applied for the same time duration. The bipolar gradient in PC-MRI is put in a sequence after RF excitation but before data collection during the echo time of the generic MRI modality.
It does not need gadolinium contrast. Dynamic contrast enhanced: DCE: Measures changes over time in the shortening of the spin–lattice relaxation (T1) induced by a gadolinium contrast bolus. Faster Gd contrast uptake along with other features is suggestive of malignancy (pictured). Functional MRI (fMRI) Blood-oxygen-level dependent imaging: BOLD
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to generate images of the organs in the body.
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).
However, greater capital costs and effects of off-resonance artefact on image quality mean that many studies are routinely performed at 1.5T. [29] Imaging at 7T field strength is a growing area of research, but is not widely available. [30] Current manufacturers of cardiac-capable MRI scanners include Philips, Siemens, Hitachi, Toshiba, GE.
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.
An MRI pulse sequence in magnetic resonance imaging (MRI) is a particular setting of pulse sequences and pulsed field gradients, resulting in a particular image appearance. [ 1 ] A multiparametric MRI is a combination of two or more sequences, and/or including other specialized MRI configurations such as spectroscopy .
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]