| PDUF | pulsed Doppler ultrasonic flowmeter |
|---|---|
| PUL | percutaneous ultrasonic lithotripsy |
| UA | absorption unsharpness; ultra-audible; ultrasonic arteriography; umbilical artery; unauthorized abse... |
| UCG | ultrasonic cardiography; urinary chorionic gonadotropin |
| UCO | ultrasonic cardiac output; urethral catheter out; urinary catheter out |
| positron emission tomography | <radiology> A highly specialised research imaging technique using short lived radioactive substances - usually those made with a cyclotron. This technique is very sensitive in picking up active tumour tissue but does not measure the size of it. Tomographic images are formed by computer analysis of photons detected from annihilation of positrons emitted by radionuclides incorporated into biochemical substances; the images, often quantitated with a colour scale, show the uptake and distribution of the substances in the tissue, permitting analysis and localization of metabolic and physiological function. Because the half-lives of the radionuclides are so short (20 minutes to 2 hours), and the equipment expensive, PET is rarely used in a clinical setting. But since its development in the mid-1970s, it has proved the most important tool yet devised for experimental investigation of the living brain, whether healthy, traumatised, or diseased. With CT and MRI, it represents a new generation of computer imaging techniques that have revolutionised medicine and physiology. Acronym: PET (20 Jun 2000) |
|---|---|
| helical computed tomography | <radiology> Computed tomography in which the X-ray tube continuously revolves around the patient, who is simultaneously moved longitudinally; computer interpolation allows reconstruction of standard transverse scans or images in any preferred plane. Synonym: helical computed tomography, helical CT, spiral CT. (20 Jun 2000) |
| X-ray computed tomography | <radiology> Tomography using X-ray transmission and a computer to reconstruct the image. See: computed tomography. (20 Jun 2000) |
| high resolution computed tomography | Computed tomography with narrow collimation to reduce volume-averaging and an edge-enhancing reconstruction algorithm to sharpen the image, sometimes with a restricted field of view to minimise the size of pixels in the region imaged; used particularly for lung imaging. Hypocycloidal tomography, body section radiography using a complex film and tube motion with a pattern resembling a three-leaf clover. (05 Mar 2000) |
| single photon emission computed tomography | <radiology> Tomographic imaging of metabolic and physiological functions in tissues, the image being formed by computer synthesis of photons of a single energy emitted by radionuclides administered in suitable form to the patient. The method uses radionuclides which emit a single photon of a given energy. The camera is then rotated 180 or 360 degrees around the patient to capture images at multiple positions along the arc. The computer then reconstructs the transaxial, sagittal, and coronal images from the 3-dimensional distribution of radionuclides in the target area scanned. The advantages of SPECT are that it can be used to observe biochemical and physiological processes as well as the size and volume of the organ. The disadvantage is that, unlike positron emission tomography where the positron-electron annihilation results in the emission of 2 photons at 180 degrees from each other, SPECT requires physical collimation to line up the photons, which results in the loss of available photons and hence degrades the image. Acronym: SPECT (20 Jun 2000) |
| spiral computed tomography | <radiology> Computed tomography in which the X-ray tube continuously revolves around the patient, who is simultaneously moved longitudinally; computer interpolation allows reconstruction of standard transverse scans or images in any preferred plane. Synonym: helical computed tomography, helical CT, spiral CT. (20 Jun 2000) |
| nuclear magnetic resonance tomography | A special imaging technique used to image internal stuctures of the body, particularly the soft tissues. An MRI image is often superior to a normal X-ray image. It uses the influence of a large magnet to polarize hydrogen atoms in the tissues and then monitors the summation of the spinning energies within living cells. Images are very clear and are particularly good for soft tissue, brain and spinal cord, joints and abdomen. These scans may be used for detecting some cancers or for following their progress. Acronym: MRI (11 Nov 1997) |
| dynamic computed tomography | Computed tomography with rapid injection of contrast medium, usually with sequential scans at only one or a few levels; used to enhance the vascular compartment. Synonym: dynamic CT. (05 Mar 2000) |
| tomography | <procedure, radiology> The recording of internal body images at a predetermined plane by means of the tomograph, also called body section roentgenography. Origin: Gr. Graphein = to write (18 Nov 1997) |
| emission-computed tomography | <radiology> Tomography using emissions from radionuclides and a computer algorithm to reconstruct the image. (20 Jun 2000) |