M's

Question 1

Mach band

Answer 1

An optical illusion in which a false black or white line occurs atnthe boundary between two different opacities. Other names: Mach line, edge enhancement.

• A negative Mach band (black line) is visible around nearly any “white” structure on radiographs (may be misinterpreted as a fracture line where bones cross). A negative Mach band also occurs along the edge of a convex structure (e.g., outer margin of bone cortex).
• A positive Mach band (white line) occurs at the edge of a concave structure (e.g., acetabulum and under femoral head on a ventrodorsal pelvic radiograph). Positive Mach bands may be mistaken for osteophytes (i.e., on the femoral neck).
• Mach bands cannot be eliminated by knowledge of their existence; the illusion occurs in the retina and the brain actually sees it.

Question 2

magnetic resonance imaging (MRI)

Answer 2

A diagnostic imaging procedure that creates cross-sectional images of a body part using powerful magnetic fields. The magnetic field temporarily alters the positions of protons in the patient. As these protons return to their normal positions, they emit radio waves that are detected by computers to create images with superior anatomic detail. The patient is not exposed to harmful radiation during an MRI procedure.

Question 3

magnification

Answer 3

Process of enlarging a radiographic image by using a small focal spot and increasing the object-film (object-receptor) distance.

Question 4

malunion fracture

Answer 4

Fracture has healed, but there is abnormal bone geometry (i.e., bone is abnormally shortened, malaligned, angled, or rotated). reduce x-ray exposure by enhancing the effect of x-rays on nfilm.

Question 5

monostotic

Answer 5

In the same bone.

Question 6

mucopolysaccharidosis

Answer 6

A group of inherited diseases characterized by accumulations of mucopolysaccharides, which can lead to permanent damage in musculoskeletal, ocular, neurologic, and circulatory systems.

Question 7

myelocele

Answer 7

Neural defect in which the spinal cord protrudes through a dorsal spinal defect.

Question 8

myelography

Answer 8

A radiographic contrast study of the spinal cord involving injection of positive contrast medium into the spinal subarachnoid space. Myelogram.

Question 9

myositis ossificans

Answer 9

The deposition of inorganic materials in muscle, usually secondary to trauma.

Question 10

mural

Answer 10

Pertaining to or occurring in the wall of a body cavity.

Question 11

manus

Answer 11

Distal part of a thoracic limb; includes carpus, metacarpus, and digits.

Question 12

mAs (milliampere seconds)

Answer 12

Product of the strength of the current through the x-ray tube (milliamperes) and the length of time the current is on (seconds). Determines the number of electrons emitted and therefore the number of x-rays produced (quantity of x-ray beam). Influences radiographic density (degree of blackness on a radiograph).

Question 13

mass effect

Answer 13

Displacement of viscera or other structures away from their normal positions without distinct visualization of the borders of a mass.

Question 14

mass lesion

Answer 14

A solitary lesion larger than 3 cm in diameter.

Question 15

median

Answer 15

Pertaining to the middle of the body.

Question 16

medial

Answer 16

Toward the midline of the body or on the inner (axial) surface of an extremity. Along the median. Contrast

lateral (Figure 2.22).

Question 17

mediastinal shift

Answer 17

Displacement of the heart and/or other mediastinal structures toward the right or left side. May be caused by alteration in lung volume, a mass lesion, unilateral fluid or gas in pleural space, or congenital defect (e.g., pectus excavatum).

Question 18

meningocele

Answer 18

Neural defect in which the meninges protrude through a dorsal spinal defect.

Question 19

meningomyelocele

Answer 19

Neural defect in which the spinal cord, meninges, or nerve roots protrude through a dorsal spinal defect.

Question 20

metaphysis

Answer 20

“Next to the physis”; wider portion of a long bone between the diaphysis and the physis. The area in a long bone where growth cartilage is transformed into cortical bone.

Question 21

metastatic calcification

Answer 21

The deposition of calcium salts in tissues away from a disease site, most often due to abnormal calcium/phosphorus metabolism.

Question 22

microlithiasis

Answer 22

Focal areas of mineralization (less than 3 mm in size) in an organ, usually the lung. (Other names: heterotopic bone formation, pulmonary osteomas).

Question 23

miliary nodules

Answer 23

Small in size, like a millet seed (1–2 mm). Other names: micronodules.

Question 24

mineralization

Answer 24

The abnormal bioprecipitation of inorganic substances (such as calcium) in organic tissue; includes petrification and fossilization. In the heart valve, mineralization tends to be small, sharp, and linear, in the coranary artery it tends to be curvilinear.

Question 25

mixed pulmonary pattern

Answer 25

Two or more lung patterns are visible concurrently (i.e., bronchointerstitial, interstitial and alveolar).

Question 26

monoarticular

Answer 26

One joint (i.e., all lesions in the same joint).