ISCD CCD key terms

The number of standard deviations a patient's bone mineral density lies above or below the mean of a young adult reference population of the same sex, used to diagnose osteoporosis in postmenopausal women and men age 50 and older.

The number of standard deviations a patient's bone mineral density lies above or below the mean of an age-, sex-, and ethnicity-matched reference population; values of -2.0 or lower prompt evaluation for secondary causes.

Classification of bone mineral density by T-score as normal (-1.0 or above), osteopenia or low bone mass (between -1.0 and -2.5), and osteoporosis (-2.5 or below), applied to postmenopausal women and men age 50 and older.

A skeletal disorder of compromised bone strength that predisposes a person to increased fracture risk, operationally defined by a T-score of -2.5 or lower or by the occurrence of a fragility fracture.

Bone mineral density that is below the young adult mean but not low enough to meet the osteoporosis threshold, corresponding to a T-score between -1.0 and -2.5.

A fracture resulting from a fall from standing height or less, or from trauma that would not ordinarily break healthy bone, commonly occurring at the hip, spine, proximal humerus, or distal forearm.

A technique that measures bone mineral content and areal bone mineral density by passing two X-ray beams of different energies through tissue, allowing soft tissue and bone to be separated mathematically.

Bone mineral content divided by the projected two-dimensional bone area in grams per square centimeter; it does not capture bone depth or true volumetric density and is influenced by bone size.

The total mass of mineral in the measured region, expressed in grams, obtained from the attenuation of X-rays along each scan line during a densitometry acquisition.

Bone mineral density expressed per unit of true three-dimensional volume, typically in milligrams per cubic centimeter, which can be estimated from areal measurements or measured directly with quantitative computed tomography.

A three-dimensional imaging method that measures volumetric bone mineral density of trabecular and cortical bone separately, unaffected by degenerative change or aortic calcification but requiring a higher radiation dose.

A texture index derived from lumbar spine dual-energy X-ray absorptiometry images that reflects trabecular microarchitecture and can refine fracture risk assessment independently of areal bone mineral density.

Bone density assessment of the first through fourth lumbar vertebrae, typically requiring at least two evaluable vertebrae and excluding vertebrae with fracture, surgery, or severe degenerative change.

Bone density assessment of the proximal femur including the femoral neck, trochanter, and intertrochanteric region, often the preferred hip site because it is reproducible and less affected by positioning variability.

Bone density assessment of the region of the proximal femur between the femoral head and the intertrochanteric line, a site commonly used for diagnosis and for fracture risk prediction.

Bone density assessment of the distal third of the nondominant forearm, a predominantly cortical site that may be used when hip and spine cannot be measured or evaluated.

The smallest difference between two measurements that can be considered statistically real rather than attributable to measurement error, calculated from the precision error at a stated confidence level.

The random variability of repeated measurements in the same person, usually expressed as a coefficient of variation or root-mean-square standard deviation, reflecting reproducibility of the technique and technologist.

A quality control procedure in which a technologist scans a set of volunteers or patients multiple times to calculate that technologist's reproducibility at each skeletal site before interpreting serial changes.

A manufactured object of known composition and density scanned periodically to verify that a densitometer remains stable and calibrated over time, independent of patient or operator variability.

The scheduled set of procedures, including phantom scanning, calibration checks, and review of control charts, that confirms a densitometry system is performing within acceptable limits.

The process of adjusting or verifying instrument output against a known standard so that measured attenuation corresponds to accurate bone mineral values across the range of clinical interest.

Rules for omitting individual vertebrae from analysis, such as prior vertebroplasty, surgical hardware, severe degenerative change, or focal structural abnormality, when they would falsely elevate bone density.

Falsely elevated bone density caused by osteophytes, facet sclerosis, or aortic calcification superimposed on the measured region, most often affecting the lumbar spine in older adults.

A lateral spine image acquired on a densitometer and evaluated for vertebral deformity, allowing detection of prevalent fractures that indicate high risk even when bone density is not osteoporotic.

A visual method for classifying vertebral fractures as mild, moderate, or severe according to the degree of height loss in the anterior, middle, or posterior vertebral dimension.

A calculator that estimates ten-year probability of major osteoporotic fracture and hip fracture from clinical risk factors with or without bone mineral density, used to guide treatment decisions.

Inputs used in fracture probability calculation, including age, sex, body mass index, prior fracture, parental hip fracture, smoking, glucocorticoid use, rheumatoid arthritis, secondary osteoporosis, and alcohol intake.

Bone loss caused by an identifiable disease, medication, or lifestyle factor rather than by aging or estrogen deficiency alone, warranting laboratory evaluation especially when the Z-score is low.

Bone loss and increased fracture risk resulting from chronic glucocorticoid therapy, with rapid early bone loss and fractures occurring at higher bone density than in postmenopausal osteoporosis.

Clinical circumstances that warrant densitometry, such as women age 65 and older, men age 70 and older, younger adults with risk factors, prior fragility fracture, or monitoring of therapy.

The time between repeat bone density tests, chosen so that expected change exceeds the least significant change and is typically two years or longer for most patients.

Laboratory analytes reflecting bone formation or resorption that can indicate treatment response or adherence earlier than density changes, though they are not used to diagnose osteoporosis.

Required acquisition and analysis practices, such as correct patient centering, consistent region-of-interest placement, and use of the same reference database, that preserve comparability of serial measurements.

Densitometric measurement of total and regional fat mass and lean mass, used in research and selected clinical settings but not part of routine osteoporosis diagnosis.

The very small effective dose delivered during a dual-energy X-ray absorptiometry examination, far below that of conventional radiography, which supports its use for screening and monitoring.