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Specialized Gen Rad > BMD > Flashcards

BMD Flashcards

1
Q

osteoporosis

A

progressive systemic skeletal disease characterized by bone mass loss

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2
Q

osteopenia

A

loss of bone density

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3
Q

what are osteoporosis & osteopenia useful for

A

quantify measure of bone mineralization & underlying bone issue

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4
Q

what hormone is important for bone preservation

A

oestrogen

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5
Q

what forms axial skeleton

A

spine, ribs, pelvis

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6
Q

what forms appendicular skeleton

A

hips, shoulders

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7
Q

cortical / compact bone

A

outer envelope of all bones & shafts of long bones

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8
Q

cancellous / trabecullar bone

A

inner parts of bone esp axial skeleton

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9
Q

osteoblast function

A

grow / build new bones

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10
Q

osteoclast function

A

break down bones

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11
Q

what are osteoblasts, osteoclasts, osteocytes useful for

A

preserving structural integrity & body balance of calcium & phsophorus

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12
Q

factors of attenuation

A

tissue density & thickness

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13
Q

DEXA?

A

dual energy x-ray absorptometry

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14
Q

how does DEXA differentiate soft tissues & bones

A

high & low peak energies

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15
Q

what is the primary way of assessing central & peripheral skeleton

A

DEXA

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16
Q

what BMD does DEXA assess for

A

areal / surface BMD

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17
Q

what does quantitative computed tomography assess

A

appendicular skeleton & spine; volumetric mineral density of bone tissue

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18
Q

what does quantitative ultrasound assess at

A

heel

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19
Q

what are DEXA methods to produce dual energies

A

K-edge (filtered x-rays) & voltage switching (switching x-rays)

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20
Q

low energy used for

A

bone attenutation > soft tissue attenuation

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21
Q

low energy levels used

A

30 - 50 keV

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22
Q

high energy levels used

A

> 70 keV

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23
Q

what happens to attenuation of bone & soft tissue when high energy levels used

A

bone attenuation similar to soft tissue attenuation

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24
Q

what is a gold standard to diagnose osteoporosis & monitor its treatment

A

DEXA

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25
Q

what are the other purposes of DEXA

A

BMD, whole body composition, vertebral # assessment

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26
Q

which part of the spine do spine scans assess

A

lumbar spine; primary site for BMD screening

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27
Q

why is lumbar spine used for BMD screening

A

lack of rib obstruction & greater consistent visual uniformity

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28
Q

what is the exclusion allowance up to and why

A

L1 - L4, 2 vertebrae allowance due to structural abnormality / artifact

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29
Q

contraindications of spine scans

A

GI tract obstruction
pregnancy
unable to lie supine/keep still
full spine/hip instrumentation

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30
Q

spine scan positioning for BMD

A
  1. patient lies supine without metallic/dense artifacts within spinal region
  2. shoulders directly under lateral indicator lines
  3. legs raised till 90 degrees at hips, supported by spine cushion
  4. arms not obstructing spinal region
  5. target centered on umbilicus & patient remains still
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31
Q

which part of the body do hip scans assess

A

proximal femur especially femoral neck & whole proximal femur

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32
Q

what is the risk of hip scans

A

high reproducibility error than spine/forearm due to femur rotational dynamics & non-uniform diametrical structure

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33
Q

how to position patient for hip scans

A
  1. patient lies supine w/o metallic/dense artifacts within femoral region
  2. hip abducted enough to straighten femur
  3. leg internally rotated to maximize frontal view of femoral neck via hip fastener
  4. hands away from proximal femur region
34
Q

what are the ROIs of hip scans

A

femoral neck
greater trochanter
total proximal femur
ward’s area

35
Q

which area is not clinically useful for hip scans

A

Ward’s area

36
Q

what is the POI of hip scans

A

lesser trochanter
ischium

37
Q

factors of BMD hip scans

A

abdominal adipose tissues = fat panniculus covers femoral neck region; needs to be held during scan

reproducibility = ideally have 15 - 20 degrees internal femoral rotation to produce lowest BMD value
- any deviation = increased BMD value
- for follow ups, repeat using same degree of rotation

38
Q

when are BMD forearm scans done

A

when hip scans are contraindicated

39
Q

BMD forearm scan clinical usefulness

A

detect cortical bone loss for patients with hyperparathyroidism

40
Q

why is non-dominant hand used for BMD forearm scans

A

dominant hand has increased BMC and BMD differences in unilateral arm activities

41
Q

T > -1

A

normal

42
Q

-2.5 < T < -1

A

osteopenia

43
Q

T < -2.5

A

osteoporosis

44
Q

T < -2.5 w/ #

A

severe osteoporosis

45
Q

T-score usefulness

A

primary diagnostic value for post-menopausal osteoporosis

46
Q

Z-score usefulness

A

diagnose low bone mass in children, pre-menopausal women, men < 50 years old

47
Q

whole body composition estimates ___

A

proportion of fat-mass to fat-free mass (bone, tissue)

48
Q

FM

A

fat mass

49
Q

LSTM

A

lean soft tissue mass

50
Q

FFM

A

fat free mass

51
Q

stm

A

soft tissue mass

52
Q

TBM

A

total body mass

53
Q

PCTFM

A

per cent fat mass

54
Q

Is DEXA scans a definitive test for osteoporosis

A

no; need to do further test for confirmation

55
Q

can ultrasound BMD be used to monitor treatment

A

no

56
Q

what are anthropometry uses of BMD

A

healthcare = nutritional status, growth & development, nutritional intervention

sports = monitor training & diet, talent ID

manufacturing = assist in designs for furniture/clothing

57
Q

direct measurement of body composition

A

cadaver dissection

58
Q

indirect measurement of body composition

A

DEXA
ultrasound
skinfold thickness
hydrodensitometry
plethysrography
air displacement

“DA PUSH”

59
Q

doubly indirect measurement of body composition

A

bioelectrical impedance
ultrasound estimated body fat %
skinfold estimated body fat %
3D photonic scanning

“3 BUS”

60
Q

2 compartment measurement of body composition

A

FFM + FM

61
Q

3 compartment measurement of body composition

A

FM + BMC + LTM

62
Q

4 compartment measurement of body composition

A

FM + BMC + Protein + total body water

63
Q

3 variables for testing

A

valid, reliable, accurate

64
Q

level 1 of validation of body compo test

A

TFM via cadaver dissection

65
Q

level 2 of validation of body compo test

A

another quantity besides fat measured; quantitative relationship made

66
Q

level 3 of validation of body compo test

A

indirect method used (skinfold thickness/bioelectrical impedance); regression relationship made

67
Q

benefits of DEXA

A

quick, low exposure, little skill & prep needed

68
Q

BMC is mineral bone mass in

A

hydroxyapatite

69
Q

how long should patients withhold Ca2+ supplement before exam

A

24 hrs

70
Q

when should u postpone DEXA scans

A

just finished barium/iodinated study & pregnant

71
Q

patient position for whole body composition

A

patient lies supine with both arms pronated & feet internally rotated, still & breathing normally

72
Q

patient position for whole body composition if too wide

A
  • offset 10 - 15 cm to left/right
  • use powerscan which uses same kVp and increased mAs / exposure time to increase x-ray flux
  • resultant image must include pelvis and entirety of one side L/R
73
Q

patient position for whole body composition if too tall

A
  • exclude head/feet based on previous scans or desired objective
  • max scan field by positioning high on table & dorsiflex feet and stabilized by velcro strap
74
Q

when can u omit feet for whole body composition

A

least amount of tissue excluded

75
Q

why keep head / part of head for whole body composition

A

highly cortical site includes tissues for appendicular assessment

76
Q

android region

A

trunk; measures visceral fat

77
Q

gynoid region

A

hips

78
Q

DEXA equivalent of natural radiation

A

3 hrs, < 0.001 mSv

79
Q

lumber spine equivalent of natural radiation

A

6 months (1.4mSv)

80
Q

mammography equivalent of natural radiation

A

26 days (0.21 mSv)

81
Q

breast tomosynthesis equivalent of natural radiation

A

33 days (0.27 mSv)

Specialized Gen Rad (13 decks)

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