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Perfusion CT or CT Perfusion is a type of Perfusion Scanning using Computed Tomography.It is helpful in the evaluation of the vascularity of tissue in the body. In this, the temporal changes in tissue density are measured, providing information about the vascularity of the tissue.
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]
After a period of time in microseconds (enough to allow the blood to circulate through the brain), a 'label' image is captured. A 'control' image is also acquired before the labeling of the blood water. A subtraction technique gives a measurement of perfusion. In order to increase SNR, collections of control and label images can be averaged.
However, coronal images require the person to hyperextend their neck, which must be avoided if any possibility of neck injury exists. [8] CT scans of the head increase the risk of brain cancer, especially for children. As of 2018, it appeared that there was a risk of one excess cancer per 3,000–10,000 head CT exams in children under the age ...
A CT scan can be performed in under a second and produce rapid results for clinicians, with its ease of use leading to an increase in CT scans performed in the United States from 3 million in 1980 to 62 million in 2007. Clinicians oftentimes take multiple scans, with 30% of individuals undergoing at least 3 scans in one study of CT scan usage. [36]
Diffusion-weighted images are very useful to diagnose vascular strokes in the brain. It is also used more and more in the staging of non-small-cell lung cancer , where it is a serious candidate to replace positron emission tomography as the 'gold standard' for this type of disease.
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 ...