Densitometry DEXA SCAN Dr Malith Kumarasinghe MBBS Colombo Osteoporosis Osteoporosis is the most common metabolic bone disorder It has been defined by the National Institutes of Health as an agerelated disorder characterized by ID: 260904
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Slide1
Bone Densitometry( DEXA SCAN)
Dr Malith Kumarasinghe
MBBS (Colombo)Slide2
Osteoporosis
Osteoporosis is the most common metabolic bone disorder. It has been defined by the National Institutes of Health as an age-related disorder characterized by
decreased bone mass and increased susceptibility to fractures
in the absence of other recognizable causes of bone loss.Slide3
Osteoporosis
Risk factors
may be superimposed upon either involutional or secondary osteoporosis, including
smoking, alcohol, poor diet, lack of exercise, an early menopause, strong family history and small frame. Slide4
Osteoporosis
The normal rate of bone loss is
2% per year
, hence 20-40% of the female bone mass is already lost by the age of 65 years of age, beginning before the menopause and accelerating afterwardsSlide5
Osteoporosis
Bone mass is the major determinant of bone strength that can be measured by non-invasive techniques, and accounts for 75-85% of this parameterSlide6
Osteoporosis
Bone densitometry is clinically indicated for the detection and assessment of osteoporosis and for the evaluation and monitoring of several diseases and therapies. These include:
1. The
detection
of osteoporosis and assessment of its severity.
2. Evaluation of
perimenopausal
women for the initiation of
estrogen
therapy.
3. Evaluation of patients with
metabolic diseases that affect the skeleton.4. Monitoring of treatment and evaluation of disease course. In addition it may be useful as an epidemiological tool and possibly in the future for screening
American Society of Bone and Mineral ResearchSlide7
Osteoporosis MeasurementPlain film, Subjective, Radiogrammetry, Osteogram
SPA
DPA
DEXA
QCT
US
MRISlide8
DEXA
Because photons of different energy are differentially attenuated by bone and soft-tissues, by measuring the percentage of each transmitted beam and then applying simple simultaneous equations, the absorption by bone alone and hence bone density can be calculated.
This measurement is not a true density but rather an areal density, represented in gms/cm
2Slide9
DEXA
DEXA has very high
accuracy
(the difference in the measurement from a known standard
)Slide10
DEXA
DXA is at present the most precise measurement of BMDSlide11
DEXA
InterpretationSlide12
Bone DensitometryDEXA spine check list
Note the age, sex, ethnicity and weight
Does this match the reference ranges?
Is the bottom of L4 roughly at the level of the iliac crests
Are there any ribs on L1
Scoliosis
Are the vertebrae correctly divided
Anything in the soft tissueSlide13Slide14Slide15
DEXA, what makes a good scan?5-15 Lines of Iliac Crest. I recommend 1/2 of L5.
5-10 Lines of T12.
2 cm of tissue on both sides of the spine.
Spine should be straight.
No metal in spine.Slide16
Common problems with spine scans.Spine isn’t straight.Scan starts in sacrum.
Scan stops too soon.
Wrong scan mode.
Scan doesn’t include L5.Slide17
46 F
Calcified bile