| echo-planar imaging | A type of magnetic resonance imaging that uses only one nuclear spin excitation per image and therefore can obtain images in a fraction of a second rather than the minutes required in traditional mri techniques. It is used in a variety of medical and scientific applications. (12 Dec 1998) |
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| through transfer imaging | The production of an ultrasound image by detection and analysis of sound on the opposite side of the body from the emitting transducer. Synonym: through transfer imaging. (05 Mar 2000) |
| thyroid imaging | <radiology> Tc-99m pertechnetate 6 mCi, I-123 sodium iodide 200 - 400 uCi PO (12 Dec 1998) |
| transfer imaging | The production of an ultrasound image by detection and analysis of sound on the opposite side of the body from the emitting transducer. Synonym: through transfer imaging. (05 Mar 2000) |
| ultrasound imaging | <investigation, procedure> A technique in which high-frequency sound waves are bounced off internal organs and the echo pattern is converted into a 2 dimensional picture of the structures beneath the transducer. (12 May 1997) |
| kidney: gallium imaging | <radiology> 10-20% of Ga-67 excreted via GU tract; no renal activity after 24hrs abnormal uptake (images at 48-72 hrs): tumour, primary renal tumour (variable uptake), lymphoma/leukaemia, metastases (e.g., melanoma), inflammation, acute pyelonephritis (88% sensitivity); abscess, lobar nephroma, others, collagen vascular disease, vasculitis, Wegener granulomatosis, amyloidosis, haemochromatosis, hepatic failure, antineoplastic drugs, transplant rejection: acute, chronic, ATN see also: gallium: indications (12 Dec 1998) |
| liver metastases: ultrasound imaging | <radiology> Echogenic (25%), colonic carcinoma, hepatocellular carcinoma, treated breast carcinoma mixed echogenicity (37.5%), breast carcinoma, rectal carcinoma, lung carcinoma, stomach carcinoma, anaplastic cancer, cervical carcinoma, carcinoid hypoechoic (37.5%), lymphoma, pancreatic carcinoma, cervical carcinoma, lung carcinoma (adenocarcinoma), nasopharyngeal carcinoma see: liver metastases (12 Dec 1998) |
| lung: gallium imaging | <radiology> Scans at 48 hrs because 50% of normals show activity at 24 hrs, focal uptake, primary pulmonary malignancy, benign disorder: granuloma, abscess, pneumonia, silicosis, multifocal/diffuse uptake, infection, TB: active lesion, miliary TB, rapidly progressive TB pneumonia, PCP: unimpressive symptoms and CXR, CMV, inflammation: sarcoid, interstitial lung disease (pneumoconiosis, idiopathic pulmonary fibrosis, lymphangitic carcinomatosis), radiation pneumonitis, drugs: bleomycin, amiodarone, contrast lymphangiography (in 50%) see: gallium: indications, uptake with normal chest film (12 Dec 1998) |
| auditory field | The space included within the limits of hearing of a definite sound, as of a tuning fork. (05 Mar 2000) |
| bright field illumination | <microscopy> The method of lighting the specimen with a solid cone of rays. Transmitted bright field illumination is performed by a substage condenser. Reflected bright field illumination is performed by a vertical illuminator. Compare: dark field illumination (05 Aug 1998) |
| bright field microscopy | <technique> Optical microscopy, in which absorption to a great extent and diffraction to a minor extent give rise to the image, as opposed to phase contrast or interference methods of microscopy. (18 Nov 1997) |
| Broca's field | The posterior part of the inferior frontal gyrus of the left or dominant hemisphere, corresponding approximately to Brodmann's area 44; Broca identified this region as an essential component of the motor mechanisms governing articulated speech. Synonym: Broca's area, Broca's field, motor speech centre. (05 Mar 2000) |
| magnetic field | The sphere of influence of a magnet. (05 Mar 2000) |
| magnetic field gradient | In magnetic resonance imaging, a magnetic field that varies with location, superimposed on the uniform field of the magnet, to alter the resonant frequency of nuclei and allow recovery of their spatial position. Synonym: field gradient. (05 Mar 2000) |
| receptive field | That part of the retina whose photoreceptors (rods and cones) pertain to a single optic nerve fibre. The response of a neuron to stimulation of its receptive field depends on the type of neuron and the part of the field that is illuminated; an "on-centre" neuron is stimulated by light falling at the centre of its receptive field and inhibited by light falling at the periphery; an "off-centre" neuron reacts in exactly the opposite fashion; that is, it is inhibited by light falling at the centre of its receptive field. In either case, the net response depends on a complex switching action in the retina. When an entire receptive field is equally illuminated, the response of receptors at the centre of the field predominates. (05 Mar 2000) |