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In addition, non-contrast images are often obtained in conjunction with contrast enhanced images in evaluating potential renal transplant donors and in the evaluation of the pancreas (in combination with contrast phases). Of note, dual-energy CT and the development of virtual "non-contrast" images (VNC imaging) may ultimately obviate the ...
A contrast agent usually shortens, but in some instances increases, the value of T1 of nearby water protons thereby altering the contrast in the image. Most clinically used MRI contrast agents work by shortening the T1 relaxation time of protons inside tissues via interactions with the nearby contrast agent.
CT cystography is performed by filling up the urinary bladder using diluted iodinated contrast to visualise any bladder injury if the subject has haematuria (blood in urine) post trauma. Since CT cystography can be done together with CT abdomen and pelvis, it has supplanted conventional cystography in such cases. [2]
A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. [1] Contrast agents absorb or alter external electromagnetism or ultrasound , which is different from radiopharmaceuticals , which emit radiation themselves.
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.
Iodinated contrast contains iodine.It is the main type of radiocontrast used for intravenous administration.Iodine has a particular advantage as a contrast agent for radiography because its innermost electron ("k-shell") binding energy is 33.2 keV, similar to the average energy of x-rays used in diagnostic radiography.
A computed tomography urography (CT urography or CT urogram) is a computed tomography scan that examines the urinary tract after contrast dye is injected into a vein. [1]In a CT urogram, the contrast agent is through a cannula into a vein, allowed to be cleared by the kidneys and excreted through the urinary tract as part of the urine.
One advantage of MRI of the brain over computed tomography of the head is better tissue contrast, [19] and it has fewer artifacts than CT when viewing the brainstem. MRI is also superior for pituitary imaging. [20] It may however be less effective at identifying early cerebritis. [21] In the case of a concussion, an MRI should be avoided unless ...