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Using contrast injected into the blood vessels, images are created to look for blockages, aneurysms (dilations of walls), dissections (tearing of walls), and stenosis (narrowing of vessel). CTA can be used to visualize the vessels of the heart, the aorta and other large blood vessels, the lungs, the kidneys, the head and neck, and the arms and ...
[3] [4] Another type of treatment possible by angiography (if the images reveal an aneurysm) is the introduction of metal coils through the catheter already in place and maneuvered to the site of aneurysm; over time these coils encourage formation of connective tissue at the site, strengthening the vessel walls.
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.
On CTPA, the pulmonary vessels are filled with contrast, and appear white. Any mass filling defects ( embolus or other matter such as fat ) appears darker. Ideally, the scan should be complete before the contrast reaches the left side of the heart and the aorta , as this may mean contrast has drained from the pulmonary arteries, or require a ...
Aneurysm means an outpouching of a blood vessel wall that is filled with blood. Aneurysms occur at a point of weakness in the vessel wall. This can be because of acquired disease or hereditary factors. The repeated trauma of blood flow against the vessel wall presses against the point of weakness and causes the aneurysm to enlarge. [20]
Intracranial pressure should not be above 15 mm Hg (ICP of 20 mm Hg is considered as intracranial hypertension). [14] Cerebral blood vessels are able to change the flow of blood through them by altering their diameters in a process called cerebral autoregulation ; they constrict when systemic blood pressure is raised and dilate when it is ...
Leptomeningeal collateral vessels from the anterior cerebral artery and posterior cerebral artery appeared to allow for perfusion of some brain tissue to persist, partially compensating for the loss of the major vessel. [6] This compensatory effect is however usually inadequate to maintain a normal blood supply. [11]
Bolus tracking is a technique to optimize timing of the imaging. A small bolus of radio-opaque contrast media is injected into a patient via a peripheral intravenous cannula . Depending on the vessel being imaged, the volume of contrast is tracked using a region of interest (abbreviated "R.O.I.") at a certain level and then followed by the CT ...