M - Glossary of Terms

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M - Glossary of Terms

mA	Abreviation for milliampere. The measure of X-ray tube current.
macerate	(mas'er-at). To soften and separate parts of by soaking or steeping, with or without heat.
maceration	(mas"er-a'shun). Process of becoming macerated.
macula lutea	(mak´yuu-la loo´te-a) A yellowish depression in the retina of the eye that contains the fovea centralis, the area of keenest vision
macro-	(mak'ro-) Prefix signifying excessive development, especially elongation; as macrocephalic, an unusually large head; also, morbid enlargement; as macrencephaly, hypertrophy or enlargement of the brain; opposed to micro-.
magnetic dipole	Current flowing in an infinitesimally small loop.
magnetic dipole moment	Vector with a magnitude equal to the product of the current flowing in a loop and the area of the current loop.
magnetic domain	An accumulation of many atomic magnets with their dipoles aligned.
magnetic permeability	The property of a material causing it to attract the imaginary lines of the magnetic field.
magnetic susceptibility	The ease with which a substance can be magnetised.
magnetism	The polarisation of a material.
magnetisation	The relative magnetic flux density in a material compared with that in a vacuum.
magnetite	The magnetic oxide of iron.
magnification	The exaggeration of the image size compared to the actual object size due to the fact that the image-forming radiation emanates from a point source and the object lies at a distance above the image recorder towards the source. Magnification factor = image size/object size.
magnitude	A number representing a quantity.
main-chain scission	The breakage of the long-chain macromolecule that divides the long, single molecule into smaller ones.
mainframe computer	A fast, medium to large, large capacity system that has multiple microprocessors
mal-	(mahl-) Prefix meaning ill, bad, badly; as malalignment, malfunction. maldevelopment.
mal	(mahl) Disease; usually qualified, as mal de mer, petit mal.
malacia	(ma-la'shi-ah) Morbid softening of any tissue; as osteomalacia, softening of bone.
malaise	Vague feeling of physical discomfort or uneasiness, as early in an illness.
malignant	(ma-lig'nant) Threatening to life; virulent. Of a tumor, cancerous, tending to metastasize.
malleus	(mal´e-us) The first of three auditory ossicles that attaches to the tympanum; commonly called the hammer.
mammary	(mam'ah-re) Of or pertaining to breast.
mammary gland	(mam´er-e) The gland of the female breast responsible for lactation and nourishment of the young.
mammilla	(ma-mil'ah) Mammary nipple; any nipple-shaped part.
mammillary line	(mam'i-ler"e) Imaginary line passing vertically through one mammilla or passing horizontally through mammillae.
mammographer	A radiologic technologist specialising in breast x-ray studies.
mammography	(mom-og'ra-fe) Radiographic examination of the breast also called mastography.
manifest illness	The stage of the acute radiation syndrome during which signs and symptoms are apparent.
manifest image	The observable image formed when the latent image undergoes the proper chemical processing.
man-made radiation	X-rays and artificially produced radionuclides used for nuclear medicine.
marrow	(mar´o) The soft connective tissue found within the inner cavity of certain bones that produces red blood cells
mAs (milliampere seconds)	mAs is an acronym for milliampere-seconds. A combination unit which is the product of the tube current (expressed in mA) and the exposure time (expressed in seconds). The total output of an X-ray tube is directly proportional to the mAs (or either of its components).
mask image	The image obtained from mask mode.
masking	The act of ensuring that no extraneous light from the viewbox enters the viewer's eyes.
mask mode	The method of temporal subtraction that results in successive subtraction images of contrast-filled vessels.
mass	A quantity of matter; expressed in kilograms In medical imaging: - A pulmonary or pleural lesion represented in a radiograph by a discrete opacity 30 mm or greater in diameter, explicitly shown or presumed to be extended in all three dimensions. Should be quali- fied with regard to opacity (especially presence of calcification), homogeneity, border characteris tics, location, and number.
mass density	The quantity of matter per unit volume.
mass-energy equivalence	Energy equals mass multiplied by the square of the speed of light.
mast cell	A type of connective tissue cell that produces and secretes histamine and heparin and promotes local inflammation.
mastication	(mas´´ti-ka´shun) The chewing of food.
masto-	(mas'to-) Prefix denoting relation to breast, as in mastocarcinoma, mastitis.
mastography	(mas-tog'ra-fe) Same as mammography.
matter	Anything that occupies space and has form or shape.
matrix	(ma´triks) The intercellular substance of a tissue. In medical imaging - the rows and columns of pixels displayed on a digital image.
maximum	(mak'si-mum) Greatest appreciable or allowable; opposite of minimum.
Maximum-intensity projection (MIP)	Reconstruction of an image by selecting the highest-value pixels along any arbitrary line through the data set and exhibiting only those pixels.
Maximum permissible dose (MPD)	The dose of radiation that would be expected to produce no significant radiation effects.
McBurney’s point	A point within the Right Lumbar region of the abdomen surface marking the base of the appendix. Specifically, one third the way along a line drawn from the right ASIS to the umbilicus.
mean lethal dose	A constant related to the radiosensitivity of a cell.
mean marrow dose (MMD)	The average radiation dose to the entire active bone marrow.
mean survival time	The average time between exposure and death.
meatus	(me-a´tus) Latin = passage; adjective - meatal. A passageway or opening into a structure.
mechanical energy	The ability of an object to do work. See also kinetic energy and potential energy.
mechanoreceptor	(mek´´a-no-re-sep´tor) A sensory receptor that responds to a mechanical stimulus.
mediad	(me'di-ad) Directed toward midsagittal plane.
medial	(me´de-al) Toward or closer to the midplane of the body.
median	(me'di-an) Having a central position; in middle; mesial.
mediastinum	(me´´de-a-sti´num) Space between pleural sacs of lungs, sternum, and thoracic spine; it contains heart and all thoracic viscera except lungs.
mediate	(me'di-it) Indirect; effected by a secondary or intervening cause or medium; not immediate.
mediate	(me'di-at). To effect by mediation; to intervene.
medical physicist	A physicist who examines and monitors the performance of imaging equipment.
medulla	(me-dul´ua) ) Marrow of bones; inner substance of an organ. such as that of kidney; tapering terminal portion of brain, medulla oblongata.
medulla oblongata	(ob´´long-ga´ta) A portion of the brain stem located between the spinal cord and the pons.
medullary	(med´ul-er´´e) (Latin=marrow) The hollow core of the diaphysis of a long bone in which marrow is found.
mega-	(meg'ah-) Prefix meaning large, as in megacephalic: also, a million times, as in megohm.
megacolon	(meg"ah-kolon) Abnormally large colon.
megalo-	(meg'a-lo-) Prefix meaning large, great, abnormal enlargement; as megalo-esophagus, megalakria, acromegaly.
meiosis	The process of germ cell division that reduces the chromosomes in each daughter cell to half the number of chromosomes in the parent cell.
Meissner's corpuscle	(m-is´nerz) See corpuscle of touch.
melanin	(mel´a-nin) A dark pigment found within the epidermis or epidermal derivatives of the skin.
melanocyte	(mel´a-no-s-it) A specialized melanin-producing cell found in the deepest layer of the epidermis.
melanoma	(mel´´a-no´ma) A dark, malignant tumor of the skin that frequently forms in moles.
membranous bone	(mem´bra-nus) Bone that forms from membranous connective tissue rather than from cartilage.
membranous labyrinth	(lab´i-rinth) A system of communicating sacs and ducts within the bony labyrinth of the inner ear that includes the cochlea and vestibular apparatus. It is filled with endolymph and surrounded by perilymph and bone.
Ménière's disease	(m-an-yarz´) Deafness, tinnitus, and vertigo resulting from a disorder of the labyrinth.
meninges	(me-nin´jez) Three membranes (dura mater. arachnoid, and pia mater) that form protective covering of brain and spinal cord.
menisci	(me-nis´ke) Wedge-shaped fibrocartilages in certain synovial joints.
meniscus	(me-nis'kus) Interarticular, crescent-shaped fibrocartilage, especially of knee.
menopause	(men´o-pawz) The period marked by the cessation of menstrual periods in the human female.
menstrual cycle	(men´stroo-al) The rhythmic female reproductive cycle, characterized by changes in hormone levels and physical changes in the uterine lining.
menstruation	(men´´stroo-a´shun) The discharge of blood and tissue from the uterus at the end of the menstrual cycle.
mental	(men'tal) Of or pertaining to chin or mind.
mesati-	(mes'ah-ti-) Prefix meaning medium. as mesatipelvic, having a medium-sized pelvis.
mesaticephalic	(mes"ah-ti-se-fal'ik). Having a head of medium or average proportions; midway between brachycephalic and dolichocephalic; same as mesocephalic.
mesencephalic aqueduct	(mez´´en-sue-fal´ik ak´wue-dukt) The channel that connects the third and fourth ventricles of the brain; also called the aqueduct of Sylvius.
mesencephalon	(mes´´en-sef´a-lon) The midbrain, which contains the corpora quadrigemina and the cerebral peduncles.
mesenchyme	(mez´en-k=1m) An embryonic connective tissue that can migrate, and from which all connective tissues arise.
mesenteric	synonymous with omental, epiploic and ligamentous.
mesenteric patches	(mes´´en-ter´ik) Clusters of lymph nodes on the walls of the small intestine; also called Peyer's patches.
mesentery	(mes´en-ter´´e) A fold of peritoneal membrane that attaches an abdominal organ to the abdominal wall.
mesial	(me'zi-al) Situated near or toward midsagittal plane; medial.
mesiodistal	(me"zi-o-dis'tal) Directed laterally or posteriorly from center or median line of dental arch.
mesion	(me'zi-on) Plane that divides body into right and left halves; midsagittal plane.
meso-	(mes'o-) Prefix meaning medium, moderate, or middle; as mesosoma, having medium stature, mesosyphilis, secondary stage of syphilis, and mesotropic, located in center of a cavity.
mesocephalic	(mes"o-se-falik) Head of medium or average size; same as mesaticephalic.
mesoderm	(mesuo-derm) The middle one of the three primary germ layers.
mesothelium	(mes´´o-the´lium) A simple squamous epithelial tissue that lines body cavities and covers visceral organs; also called serosa.
mesothelioma	Tumor developing from the surface of the pleura, pericardium, or peritoneum.
mesovarium	(mes´´o-va´re-um) The peritoneal fold that attaches an ovary to the broad ligament of the uterus.
meta-	(metah) Prefix signifying change or transfer, as in metabolism, metabasis: along with, after, or next, as in metatarsus.
metabolism	Anabolism and catabolism.
metacarpus	(met´´a-kar´pus) The region of the hand between the wrist and the phalanges, including the five metacarpal bones that support the palm of the hand.
metaphase	The phase of cell division during which the chromosomes are divisible.
metaphysis	(me-tafi-sis) Zone of spongy bone between cartilaginous epiphyseal plate and diaphysis of a long bone.
metastasis	(me-tas´ta-sis) Transfer of a disease from one organ or region to another, as a malignant tumor spreading from initial location to secondary locations in body.
metastasize	(me-tas'tah-siz). To form new or secondary sites of infection in other parts of body by metastasis, as a tumor.
metatarsus	(met´´a-tar´sus) The region of the foot between the ankle and the phalanges that includes the five metatarsal bones.
metencephalon	(met´´en-sef´a-lon) The most superior portion of the hindbrain that contains the cerebellum and the pons.
metol	A secondary constituent used in the chemical composition of developing agents.
metra	(me'trah) Uterus
metro-	(me-tro-) Prefix denoting relation to uterus, as in metrocarcinoma metrins.
micro-	(mi-kro) Prefix meaning small, minute, as in microbe, microcephaly; one millionth part of, as in microfarad.
microcalcifications	Calcific deposits that appear as small grains of varying sizes on the x-ray film.
microcephalic	(mi"kro-se-fal'ik) Having an unusually small head.
microcomputer	A personal computer or electronic organizer.
microcontroller	A tiny computer installed in an appliance.
micro focus tube	A tubes that has a very small focal spot and that is specifically designed for imaging very small microcalcifications at relatively short source to image distances.
microvilli	(mi´´kro-vil´i) Microscopic hairlike projections of cell membranes on certain epithelial cells.
microwave	A short-wavelength radiofrequency.
micturition	(mik´´tu-rish´un) The process of voiding urine; also called urination.
midbrain	The portion of the brain between the pons and the forebrain.
midclavicular lines	Longitudinal lines drawn from the mid-point of the clavicle to the mid-point of the inguinal ligament.
mid-density step	The step that has an average optical density closest to, but not less than, 1.2.
middle ear	The middle of the three portions of the ear that contains the three auditory ossicles.
midsagittal plane	(mid-saj´i-tal) A plane that divides the body into equal right and left halves; also called the median plane or midplane.
miliary pattern	A collection of tiny discrete pulmonary opacities that are generally uniform in size and widespread in distribution, each of which measures 2 mm or less in diameter. This pattern usually implies a bloodborne source.
milliampere (mA)	The measure of X-ray tube current.
milliampere-second (mAs)	The product of exposure time and x-ray tube current; a measure of the total number of electrons.
minification gain	The ratio of the square of the diameter of the input phosphor to the square of the diameter of the output phosphor.
miscible	(mis'i-bl) Susceptible to being readily mixed; mixable.
misregistration	Misalignment of two or more images because of patient motion between image acquisition.
mitochondria	(mi´´to-kon´dre-a), sing. mitochondrion Cytoplasmic organelles that serve as sites for the production of most of the cellular energy; the so-called powerhouses of the cell.
mitochondrion	A structure that digests macromole cules to produce energy for the cell.
mitosis (M)	The process of somatic cell division wherein a parent cells divides to form two daughter cells identical to the parent cell.
mitral valve	(mi´tral) The left atrioventricular heart valve; also called the bicuspid valve.
mixed nerve	A nerve that contains both motor and sensory nerve fibers.
mixture	(miks'chur). Heterogeneous substance made up of two or more ingredients that retain their own properties and can be separated by mechanical means.
mobility	(mo-bil'i-te) Capacity or facility of movement of an organ, such as stomach, gallbladder. or kidney.
modem	A device that converts digital information into analog information.
modulation	A changing of the magnitude of a video signal; the magnitude is directly proportional to the light intensity received by the television-camera tube.
modulation transfer function (MTF)	A mathematical procedure for measuring resolution.
molecule	A group of atoms of various elements held together by chemical forces; the smallest unit of a compound that can exist by itself and retain all its chemical properties.
molybdenum	A target material for X-ray tubes that is used in mammography.
momentum	The product of the mass of an object and its velocity.
mono-	(mon'o) Prefix meaning one, single, alone; as monoplegia, paralysis af-fecting but one part of body.
monoclonal immunoglobulin	Antibodies that are formed against a specific cell type.
monoenergetic	Consisting of photons of a single energy. An equivalent term is monochromatic which refers to photons of a single wavelength.
monosaccharide	A sugar.
mons pubis	(monz pyoo´bis) A fatty tissue pad covering the symphysis pubis and covered by pubic hair in the female.
morbid	(morbid) Disease; of or pertaining to an abnormal or diseased condition.
morgagni hernia	Protrusion of abdominal contents into the anterior and lateral aspects of the thoracic cavity.
moribund	(mor'i-bund) Near death; a dying state.
morphologic	Pertaining to the form and structure of an organ.
mortification	(morti-fi-ka-shun)Death of a part or localized area of tissue; old term for gangrene.
motherboard	The main circuit board in a system unit.
motility	(mo-til'i-te) Capacity to move or contract spontaneously; contractility.
motion blur	The blurring of the image that results from movement of either the patient or the x-ray tube during exposure.
motion unsharpness	The image unsharpness caused by movement of the patient or of the X-ray tube during the exposure.
motor area	A region of the cerebral cortex from which motor impulses to muscles or glands originate.
motor nerve	A nerve composed of motor nerve fibers.
motor neuron	(noor´on) A nerve cell that conducts action potentials away from the central nervous system and innervates effector organs (muscle and glands). It forms the anterior roots of the spinal nerves; also called an efferent neuron.
motor unit	A single motor neuron and the muscle fibers it innervates.
mottle	see radiographic mottle.
moving grid	A grid that moves while the X-ray exposure is being made.
mucoid	(mu'koid) Resembling mucus.
mucosa	(mu-ko´sa) A mucous membrane that lines cavities and tracts opening to the exterior.
mucous	(mu'kus) Of or pertaining to mucus.
mucous cell	(mu´kus) See goblet cell.
mucous membrane	(A thin sheet consisting of layers of visceral organs that include the lining epithelium, submucosal connective tissue, and(in some cases) a thin layer of smooth muscle (the muscularis mucosa).
mucus	(mu'kus) Viscid, watery fluid secreted by mucous glands.
Muller maneuver	(Johannes Peter Muller, German physiologist, 1801-1858) Forced inspiration against a closed glottis; maneuver is performed by closing mouth, holding nose, and attempting to breathe in.
multi-	(mufti-) Prefix meaning many, much; as multilobular, composed of many lobes.
multilocular	Having many cells or compartments.
multipara	(mul-tip'a-rah) Woman who has borne two or more children.
multiplanar reformation (MPR)	Process in which transverse images are stacked to form a three-dimensional data set.
multislice computed tomography	An imaging modality that uses two detector arrays to produce two spiral slices at the same time.
multitarget or single-hit model	A model of radiation dose-response relationship for more complicated biologic systems, such as human cells.
mummify	(mum'mi-fT) Term that, as used in nursing and radiographic procedures, means to wrap body in a mummy fashion with a sheet, binding arms to sides, to restrain movement during examination or treatment.
Murphy’s point	Surface marking for the Gall Bladder. Where the midclavicular line and the transpyloric plane cross on the right side.
muscle	(mus´el) A major type of tissue adapted to contract. The three kinds of muscle are cardiac, smooth, and skeletal.
muscle group	Muscles rarely act in isolation. They are formed as part of a group usually supplied with the same nerve and within one fascial (see fascia) compartment, and it is the group as a whole that acts. So not only need you not worry about remembering which end of a muscle is the origin and which the insertion (see attachments), in many cases you need not worry about individual muscles - only muscle groups.
muscularis	(mus´´kyuu-la´ris) A muscular layer or tunic of an organ, composed of smooth muscle tissue.
mutual induction	The process of producing electricity in a secondary coil by passing an alternating current through a nearby primary coil.
mycoplasma	Colloquial usage for any of a genus of tiny microorganisms, smaller than bacteria but larger than viruses, that appear to be the causative agents of many diseases.
mydriasis	dilation of the pupils
myel	(mi'el) Spinal cord; myelon.
myelencephalon	(mi´´e-len-sef´a-lon) The posterior portion of the hindbrain that contains the medulla oblongata.
myelin	(mi´e-lin) A lipoprotein material that forms a sheathlike covering around nerve fibers.
myelin sheath	A sheath surrounding axons formed by successive wrappings of a neuroglial cell membrane. Myelin sheaths are formed by neurolemmocytes in the peripheral nervous system and by oligodendrocytes within the central nervous system.
myelitis	(mi-e-li'tis). Inflammation of spinal cord or of bone marrow.
myelo-	(mi'e-lo-) Prefix denoting relation to bone marrow or to spinal cord; as myeloma, myelomeningitis.
myelography	(mi"e-log'ra-fe) Radigraphic examination of spinal cord following injection of contrast medium into spinal canal.
myenteric plexus	(mi´´en-ter´ik plek´sus) A network of sympathetic and parasympathetic nerve fibers located in the muscularis tunic of the small intestine; also called the plexus of Auerbach.
myo-	(mi'o-) Prefix signifying relation to a muscle or muscles; as myocarditis, myositis.
myocardial infarction	(mi´´o-kar´de-al in-fark´shun) An area of necrotic tissue in the myocardium that is filled in by scar (connective) tissue.
myocardium	(mi´´o-kar´de-um) The cardiac muscle layer of the heart.
myology	(mi-ol´o-je) The science or study of muscle structure and function.
myoma	(mi-o'mah). Tumor consisting of muscular elements.
myometrium	(mi´´o-me´tre-um) The layer or tunic of smooth muscle within the uterine wall.
myopia	(mi-o´pe-a) A visual defect in which objects may be seen distinctly only when very close to the eyes; also called shortsightedness.
myotomes	The skeletal muscle/muscle group supplied by one spinal cord segment (motor) (see dermatomes).
myxedema	Puffy thickening of the skin with slowing down of physical and mental activity caused by failure of the thyroid gland.