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In CT perfusion, a contrast media injection is given, and then the scan is taken. The acquired data are post-processed to obtain perfusion maps with different parameters, such as BV (blood volume), BF (blood flow), MTT (mean transit time), and TTP (time to peak).
Ventilation/perfusion scans, sometimes called a VQ (V=Ventilation, Q=perfusion) scan, is a way of identifying mismatched areas of blood and air supply to the lungs. It is primarily used to detect a pulmonary embolus. The perfusion part of the study uses a radioisotope tagged to the blood which shows where in the lungs the blood is perfusing.
CT Perfusion scan of the brain. CT perfusion imaging is a specific form of CT to assess flow through blood vessels whilst injecting a contrast agent. [21] Blood flow, blood transit time, and organ blood volume, can all be calculated with reasonable sensitivity and specificity. [21]
A ventilation/perfusion lung scan, also called a V/Q lung scan, or ventilation/perfusion scintigraphy, is a type of medical imaging using scintigraphy and medical isotopes to evaluate the circulation of air and blood within a patient's lungs, [1] [2] in order to determine the ventilation/perfusion ratio.
For cardiac scans, combining CT cardiac data with PET metabolic or perfusion data from PET/CT machines may be of clinical value. While there are unresolved issues with using a high-speed CT scan for attenuation correction of cardiac images, many new CT scanners are marketed with PET scanners and can be used to measure myocardial thickening ...
The dense MCA sign is caused by a fresh thrombus or embolus occluding the lumen of the middle cerebral artery. A thrombus with a high concentration of red blood cells and fibrin has increased density relative to normal flowing blood, leading to its hyperattenuating appearance on a non-contrast CT scan.
State of the art modern CT scanners with a scan rate of up to 320 mm/s can acquire all the images within a 1-second X-ray exposure, avoiding the problems of respiratory motion, cardiac motion and contrast draining from the pulmonary circulation during the study. Even though the actual scan may be completed in 1 second or less, considerable ...
In conventional CT machines, an X-ray tube and detector are physically rotated behind a circular shroud (see the image above right). An alternative, short lived design, known as electron beam tomography (EBT), used electromagnetic deflection of an electron beam within a very large conical X-ray tube and a stationary array of detectors to achieve very high temporal resolution, for imaging of ...