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A CT pulmonary angiogram, in this case showing pulmonary embolism of saddle-type, which becomes more radiolucent than the radiocontrast filled blood surrounding it (but it may be indistinguishable without radiocontrast). Contrast CT, or contrast-enhanced computed tomography (CECT), is X-ray computed tomography (CT) using radiocontrast.
Meaning s̅: without (s with an overbar) (from Latin sine) S: sacrum: S x: symptoms surgery (though deemed by some as inappropriate) S 1: first heart sound: S 2: second heart sound: S 3: third heart sound S 4: fourth heart sound S&O: salpingo-oophorectomy Sb: Scholar batch SAAG: serum–ascites albumin gradient SAB: staphylococcal bacteremia
The Principle of Nonvacuous Contrast proposes that for any statement, concept, or proposition to hold meaning, there must exist a demonstrable contrast between the subject and other potential subjects or concepts. In other words, in order to define and understand something, it is necessary to differentiate it from other things that it is not.
The contrast material is radiodense causing it to light up brightly within the blood vessels of interest. In order for the CT scanner to be able to scan the correct area where the contrast is, the scanner uses either automatic detectors which start scanning when enough contrast is present, or small test boluses.
This is useful to highlight structures such as blood vessels that otherwise would be difficult to delineate from their surroundings. Using contrast material can also help to obtain functional information about tissues. Often, images are taken both with and without radiocontrast. [209]
It suggests that meaning is not inherent in a sign but arises from its relationships with other signs, a continual process of contrasting with what comes before and later. That is, a sign acquires meaning by being different from other signs. The meaning of a sign changes over time, as new signs keep appearing and old signs keep disappearing.
An intravenous cannula is required for the administration of iodinated contrast. The typical dose is 30-40 g of iodine (corresponding to 20–30 cc of 370 mg/ml iodine solution). [10] However, for patients at high risk of contrast-induced nephropathy, it is possible to reduce the required amount of contrast using dual energy CT.
In philosophy, deconstruction is a loosely-defined set of approaches to understanding the relationship between text and meaning.The concept of deconstruction was introduced by the philosopher Jacques Derrida, who described it as a turn away from Platonism's ideas of "true" forms and essences which are valued above appearances.