| endocardial cushion defect | <radiology> Persistence of primitive atrioventricular canal and anomalies of AV valves associated with: Down syndrome: in 25% of Trisomy 21 an ECD is present; in 45% of ECD Trisomy 21 is present, asplenia/polysplenia types: complete (AV canal), partial findings: gooseneck deformity on angiogram, increased pulmonary vascularity, enlarged pulmonary artery, enlarged RV, LV, RA; normal LA (secondary to atrial septal defect) (12 Dec 1998) |
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| enzyme defect | A disorder resulting from a deficiency (or functional abnormality) of an enzyme. In 1902 Archibald Garrod first attributed a disease to an enzyme defect: an inborn error of metabolism. Today, newborns are routinely screened for certain enzyme defects such as PKU (phenylketonuria) and galactosaemia, an error in the handling (metabolism) of the sugar galactose. (12 Dec 1998) |
| fibrous cortical defect | A common 1 to 3 cm defect in the cortex of a bone, most commonly the lower femoral shaft of a child, filled with fibrous tissue. Nonosteogenic or nonossifying fibroma by convention refers to lesions greater than 3 cm in diameter. See: nonossifying fibroma. Synonym: nonosteogenic fibroma. (05 Mar 2000) |
| uterine filling defect | <radiology> Technical, bubble, blood clot, mucoid material, congenital fold, pseudoadhesions / ridging -- folds long axis, neoplasm, submucosal leiomyoma, adenoma, endometrial carcinoma, pregnancy-related, pregnancy, molar pregnancy, retained conceptus, polyp, septated uterus, synechiae, IUD, iatrogenic (post-op) (12 Dec 1998) |
| filling defect | Displacement of contrast medium by a space-occupying lesion in a radiographic study of a contrast-filled hollow viscus, such as a polyp on a barium enema; also applied to defects in the otherwise uniform distribution of radionuclide in an organ, such as a metastasis in the liver on a 99mTc-sulfur colloid scan. (05 Mar 2000) |
| filling defect in renal collecting system | <radiology> Common causes: transitional cell carcinoma, blood clot, lucent calculus (urate) less common causes: fungus ball, sloughed papilla, fibroepithelial polyp, invasion by hypernephroma, malakoplakia, vessel impression, metastases (12 Dec 1998) |
| lambdoid suture defect | <radiology> Well-defined lucent lesion, classically unilateral, associated with neurofibromatosis (12 Dec 1998) |
| luteal phase defect | Inadequate function of the corpus luteum that may prevent a fertilized egg from implanting in the uterus or may lead to early pregnancy loss. (09 Oct 1997) |
| 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 imaging | <microscopy> An imaging mode in a transmission electron microscopy that uses only unscattered Electrons to form the image. Contrast in such an image is due entirely to mass-thickness variations in amorphous samples, and may include diffraction contrast in crystalline samples. (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) |
| cardioid dark field condenser | <microscopy> A condenser designed with two reflecting surfaces, the first, a spherical surface which reflects the rays to a second, cardioid (heart-shaped) surface. The virtue in such an arrangement is that, if the cardioid surface is of true figure, the lens is both achromatic and aplanatic. It has a limiting numerical aperture of about 1.0. Thus objectives of a greater numerical aperture cannot be used successfully with it. A true cardioid figure is the trace of a point on the circumference of a circle rolling around an equal, fixed circle. (05 Aug 1998) |
| magnetic field | The sphere of influence of a magnet. (05 Mar 2000) |