Bone Densitometry Course Flashcards
(520 cards)
1
Q
What percentage of bone matrix is collagen?
A
90%
2
Q
What type of collagen is found in bone matrix?
A
Type 1 collagen
3
Q
Type 1 collagen contains cross links which three thing?
A
- N-telopeptides
- C-telopeptides
- deoxypyridinolines
4
Q
What percentage of bone matrix is made of proteins?
A
10%
5
Q
What three proteins are present in bone matrix?
A
- osteocalcin
- osteonectin
- osteopontin
6
Q
What is bone mineral composed of?
A
Hydroxyapatite
Calcium and phosphorus
7
Q
Name four types of bone cells.
A
- Osteoblasts
- Osteoclasts
- Osteocytes
- Lining cells
8
Q
Where are osteoclasts derived from?
A
Bone marrow precursors
9
Q
Where are osteoblasts derived from?
A
Mesenchymal precursors
10
Q
What is the process of mineralization of bone called?
A
Formation
11
Q
What happens to bone mineral density during adolescence?
A
It dramatically increases
12
Q
What happens to bone mineral density during late teens and early twenties?
A
Peak bone mass is achieved.
13
Q
What happens to bone mineral density during after menopause?
A
There is accelerated bone loss.
14
Q
How long does the accelerated phase of bone loss after menopause last?
A
5 - 10 years
15
Q
Is bone mineral density higher in men or women?
A
Men
16
Q
Is bone mineral density higher in blacks or whites?
A
Blacks
17
Q
How variable are average bone densities?
A
Very variable
Above-average white women have higher BMD than below average black men.
18
Q
What percentage of cortical bone is renewed each year?
A
3%
19
Q
What percentage of cancellous bone is renewed each year?
A
25%
20
Q
What percentage of the skeleton is being remodeled at any one time?
A
10%
21
Q
Which type of bone loss is rapid in early menopause?
A
Cancellous bone loss
22
Q
Which body part fractures increase in frequency as cancellous bone loss begins in early menopause?
A
Wrist fractures
23
Q
Which bone loss is more gradual after menopause, cancellous or cortical?
A
Cortical
24
Q
Does the risk of hip fractures after menopause increase as a result of cancellous or cortical bone loss?
A
Bone
25
Why does bone loss occur with increasing age?
Because resorption is greater than formation.
26
If a bone breaks under conditions that would not cause a normal bone to break - what kind of fracture is it?
Fragility fracture
27
Does bone loss have any symptoms?
No
28
What is the prevalence of disease?
Frequency of disease at a specific point in time.
Number with disease/risk
29
What is the prevalence of women over age 50 years with osteoporosis?
30%
30
What is the incidence of a disease?
The new cases of a disease over a specific period of time.
New cases within the period of time/number of risk
31
What is the incidence of hip fractures in the elderly population?
12 per 1000 person-years
32
How many people are estimated to have osteoporosis worldwide?
200 million
33
Hip fracture is projected to increase ____ % in women by 2050.
240%
34
Hip fracture is projected to increase ____ % in men by 2050.
320%
35
Even if there is no increase in age-related hip fracture risk, the number of hip fractures will increase from _____ in 1990 to _____ in 2050.
1.7 million to 6.3 million
36
Is it easier to diagnose osteoporosis in the spine or the hip as you get older?
The hip. Spine becomes harder to use because of degenerative changes.
37
Rochester Osteoporosis Project: Prevalence
At younger ages, the prevalence of osteoporosis at the _____ is higher than the prevalence at the _____.
Spine higher than hip
38
Rochester Osteoporosis Project: Prevalence
At older ages, the prevalence of osteoporosis at the _____ is higher than the prevalence at the _____.
Hip higher than spine
39
Rochester Osteoporosis Project: Prevalence
Overall is the prevalence of osteoporosis higher at the hip or the spine.
Overall, the prevalence is similar.
40
Which skeletal sites did the NHANES III use?
Only proximal femur (hip)
41
What was the NHANES III reference population?
White men and women, aged 20 - 29, from multiple geographic regions of the US.
42
What was the study population of the NHANES III?
Men and women aged 50 years or more, difference races, from multiple regions of the US.
43
NHANES III
Prevalence of osteoporosis based on femoral neck measurements in white women aged 50 and older?
22%
44
NHANES III
Prevalence of osteoporosis based on femoral neck measurements in Hispanic women aged 50 and older?
10%
45
NHANES III
Prevalence of osteoporosis based on femoral neck measurements in black women aged 50 and older?
5%
46
NHANES III
Prevalence of osteoporosis based on femoral neck measurements in men aged 50 and older?
6%
47
NHANES III
Prevalence of low bone mass in women aged 50 - 59 years?
40%
48
NHANES III
Prevalence of low bone mass in women aged older than 80 years?
Over 90%
49
National Osteoporosis Foundation (NOF)
How many people in the US have osteoporosis?
10 million people
50
National Osteoporosis Foundation (NOF)
How many women in the US have osteoporosis?
8 million women
51
National Osteoporosis Foundation (NOF)
How many men in the US have osteoporosis?
2 million men
52
National Osteoporosis Foundation (NOF)
How many people in the US have low bone mass?
34 million people
53
National Osteoporosis Foundation (NOF)
How many people in the US will there be with osteoporosis in 2020?
(Estimate)
Almost 14 million people
54
What is a pathological fracture?
A fracture that occurs in an area of bone already weakened by another process i.e. tumor, infection, inherited bone disorder etc.
55
What is a stress fracture?
A hairline fracture resulting from repeated stress.
56
What is an osteoporotic fracture?
Fracture occurring with minimal trauma such as a force less than or equal to falling from standing height.
57
Fracture incidence is bimodal - when are the two peaks?
Youth: 15 - 25 years
| Over age 45 years
58
Which fractures pre-dominate in young people?
Fractures of long bones
59
In young people is the incidence of traumatic fractures greater in women or men?
Men
60
What type of fractures increase after age 45 years?
Fragility fractures
61
Do men or women have more fragility fractures?
Women
62
NOF
Approximately how many osteoporosis fractures per year are there in the US (incidence)?
1.5 million
63
NOF
Approximately how many osteoporosis spine fractures per year are there in the US (incidence)?
700,000 spine fractures
64
NOF
Approximately how many osteoporosis hip fractures per year are there in the US (incidence)?
300,000 hip fractures
65
NOF
Approximately how many osteoporosis wrist fractures per year are there in the US (incidence)?
250,000
66
NOF
Approximately how many osteoporosis fractures other than spine, hip and wrist per year are there in the US (incidence)?
300,000
67
Asymptomatic fractures account for about _____ % of all vertebral fractures.
65 - 75%
68
When does the incidence of forearm fractures begin to rise in women?
Age 45 - 50 years
69
When does the incidence of forearm fractures level off in women?
Around age 65 years
70
Is there an increase in the rate of foreman fractures in men?
No
71
When does the incidence of clinical vertebral fractures begin to rise in women?
Age 55 - 60
| It rises linearly after this
72
When does the incidence of clinical vertebral fractures begin to rise in men?
Age 60 - 70 years
73
When does the incidence of hip fractures begin to rise in women?
Age 65
| Increases exponentially
74
When does the incidence of hip fractures begin to rise in men?
Age 70 - 75
75
What kind of fracture is more likely when you fall forward (younger women)?
Wrist fracture
76
What kind of fracture is more likely when you fall sideways (older women)?
Hip fracture
77
What is the third most common osteoporotic fracture?
Distal forearm fracture
78
If you have a distal forearm fracture, then what is the risk of future fracture?
Relative risk of forearm fracture?
3.3
79
If you have a distal forearm fracture, then what is the risk of future fracture?
Relative risk of vertebral fracture?
1.7
80
If you have a distal forearm fracture, then what is the risk of future fracture?
Relative risk of hip fracture?
1.9
81
Reflex sympathetic dystrophy is a complication of which fracture?
Distal forearm fracture
82
In distal forearm fractures, what percentage report fair/poor recovery in functional recovery 6 months after fracture?
23%
83
6 months following ER presentation of wrist fracture in untreated patients, what percentage of patients had a DXA in the control group?
Majumdar CAMJ 2008; 178:569-575
18%
84
6 months following ER presentation of wrist fracture in untreated patients, what percentage of patients were given bisphosphonates in the control group?
Majumdar CAMJ 2008; 178:569-575
7%
85
What three types of vertebral fractures are they?
- Wedge
- Biconcave
- Crush
86
If you have a vertebral fracture, then what is the risk of future fracture?
Relative risk of hip fracture?
2.3
87
If you have a vertebral fracture, then what is the risk of future fracture?
Relative risk of vertebral fracture?
4.4
88
If you have a vertebral fracture, then what is the risk of future fracture?
Relative risk of forearm fracture?
1.4
89
What percentage of vertebral fractures seen on x-ray are diagnosed clinically?
25 - 30%
90
By what percentage does vital capacity decrease as a consequence of vertebral fractures?
9%
91
What percentage of hip fractures occur at the femoral neck?
40%
92
What percentage of hip fractures occur at the intertrochanteric region?
40%
93
What is the second most common osteoporotic fracture?
Hip fracture
94
What percentage of osteoporotic fractures are spontaneous?
5%
95
What percentage of falls lead to hip fractures?
1%
96
What is the excess mortality within 1 year after a hip fracture?
24 - 30%
97
How many American women die from complications of hip fracture every year?
65,000
98
What percentage of hip fracture survivors are permanently incapacitated?
50%
99
What percentage of hip fracture survivors require long-term nursing home care?
20%
100
Kamel HK, et al. Am J Med. 2000; 109:326-328
In this study of 170 patients hospitalized for hip fracture, diagnosis and treatment for osteoporosis occurred in less than ___%.
10
101
After hip fracture, mortality is in the first _____ months.
6 - 12
102
Is the increase in mortality sudden or gradual after a vertebral fracture?
Gradual
103
By what percentage is five-year excess mortality increased by in both hip and spine fractures?
About 20%
104
What percentage of health care dollars for osteoporosis are spent for hospitalisation?
62%
105
What percentage of health care dollars for osteoporosis are spent for nursing home care?
28%
106
What percentage of health care dollars for osteoporosis are spent for outpatient care?
10%
107
What was the cost of osteoporosis in 1997?
13.8 billion dollars
108
What was the cost of osteoporosis in 2005?
19 billion dollars
109
What is the projected cost (annually) for total fractures by 2025?
25 billion dollars
110
How many people in the United States have low bone density and osteoporosis?
(2010 estimate)
42.4 million
111
How many people in the United States have hypercholestrolemia?
(2010 estimate)
98.6 million
112
How many people in the United States have hypertension?
| 2010 estimate
73.5 million
113
How many people in the United States have diabetes?
| 2010 estimate
23.6 million
114
In older women, the incidence of osteoporotic fractures (about ___ million) is ______ than the incidence of myocardial infarction, stroke, and breast cancer combined.
2 million
| Greater
115
What is the clinical utility of bone densitometry?
- Diagnosis (WHO T-score classification)
- Prognosis (Fracture risk assessment)
- Monitoring (Requires knowledge of precision and LSC)
116
Do all patients with T-score -2.5 or below have osteoporosis?
No
117
Do all patients with T-score above -2.5 not have osteoporosis?
No
118
T-scores may differ at different skeletal sites.
True or false?
True
119
Does the diagnosis of osteoporosis explain the etiology of it?
No
120
Does everyone with osteoporosis have the same fracture risk?
No
121
Does a low bone mineral density equal bone loss?
No
122
Can a single BMD examination distinguish between low peak BMD followed by normal rate of loss or normal peak BMD with accelerated rate of loss?
No
123
What is the rationale for using BMD to predict fracture risk?
(2 points)
- BMD is correlated with bone strength in biomechanical studies.
- BMD is predictive of future fractures in epidemiologic studies.
124
The strength of cortical bone decreases by _____ % per decade after age 20.
2 - 5%
125
In cancellous bone _____ % variability in elastic modulus explained by apparent density (bone mass per unit volume of marrow and bone tissue).
60 - 80%
126
Is the correlation between vertebral BMD and failure load better for DXA or QCT?
DXA
127
Is there a strong correlation between femoral BMD and failure load?
Yes
128
What are the two best predictors of fracture load at the distal radial?
- Cortical width
| - Cortical area
129
Which two reference populations is the 10-year probability of fracture risk assessment based on?
- NHANES III
| - Swedish population
130
What are the four features of an ideal skeletal site to serially monitor changes in BMD?
- Rapid bone turnover
- Low precision error
- Rapid response to therapy
- Greatest response to therapy
131
What is the best site to use for monitoring serial changes in BMD?
Lumbar spine
132
Central devices can measure bone density of which regions of interest?
(Four areas)
- Spine
- Hip
- Forearm
- Total body
133
Peripheral devices can measure bone density of which regions of interest?
(Three examples)
- Heel
- Finger
- Wrist
134
What are bone density instruments classified by?
Their primary technology platform
135
What two technology platforms exist for bone density?
- X-ray based
| - Ultrasound based
136
Is the proximal femur a peripheral or central skeletal site?
Central
137
Which lumbar vertebrae does bone density analysis include?
L1 - L4
138
Which lumbar vertebrae looks like a 'bow-tie' or a 'dog bone'?
L5
139
Which lumbar vertebrae is 'box' or 'X-shaped'?
L4
140
Which lumbar vertebrae are 'U-shaped'?
L1 - L3
141
What are the four regions of interest in the hip?
- Femoral neck box
- Total hip
- Greater and lesser trochanters
- Ward's area
142
Name two central densitometry devices.
- Dual-energy x-ray absorptiometry (DXA)
| - Quantitative computed tomography (QCT)
143
What is the 'gold standard' for bone density measurement?
Central DXA
144
Central DXA has excellent reproducibility.
True or false?
True
145
What is the radiation dose from central DXA?
1 - 3 microSv (low radiation dose)
146
Which technique for bone density measurement as been used in most epidemiological studies?
Central DXA
147
Is it well known how DXA-measured BMD relates to fracture risk?
Yes
148
Which method of bone density measurement is used to select subjects for therapy and to document response to treatment over time in pharmaceutical trials?
Central DXA
149
Name five peripheral densitometry devices.
- Peripheral DXA
- Single x-ray absorptiometry (SXA)
- Peripheral QCT (pQCT)
- Quantitative ultrasound (QUS)
- Radiographic absorptiometry (RA)
150
What is attenuation?
A reduction in the number and energy of photons in an x-ray beam (decreased intensity of x-ray beam)
151
What is attenuation determined by?
Tissue density and thickness
152
Does denser tissue contain more of less electrons?
More electrons
153
What else can you quantify when degree of attenuation is quantified?
Tissue density
154
Can you separate how much mass is due to bone, soft tissue or both with single energy x-ray beam?
No
155
With dual energy x-ray beams the proportion of radiation transmitted through the patient depends on which three factors?
- Energy of x-ray photons
- Physical density of the body
- Body thickness
156
What is the difference between a single energy and dual energy x-ray beams?
Single energy x-rays have one photon energy while dual energy x-rays have two different photon energies.
157
What two energies are used in dual energy x-ray absorptiometry?
- Low energy (30 - 50 keV)
| - High energy (>70 keV)
158
Which is greater at low energy...
Bone attenuation or soft tissue attenuation?
Bone attenuation
159
Which is greater at high energy...
Bone attenuation or soft tissue attenuation?
Bone attenuation is similar to soft tissue attenuation.
160
Can dual x-ray attenuation distinguish bone and soft-tissue?
Yes
161
What three parts do DXA systems have?
- X-ray tube
- Collimator
- X-ray detector
162
What are x-ray photons produced by?
X-ray tube
163
What does an X-ray tube consist of?
An X-ray tube consists if a cathode (negative charged) and an anode (positively charged) encased in a vacuum tube.
164
What percentage of X-ray tube energy appears as x-rays?
Less than 1%
165
What percentage of X-ray tube energy is lost as heat?
99%
166
What does the collimator do?
Focuses the x-ray beam
167
The type of detector depends on the type of system --- what types are they?
K-edge filter vs voltage switching
| Pencil-beam vs fan-beam
168
What are the x-ray tube, collimator, and detector aligned and mechanically linked using?
Scanner arm
169
Which detector/system is used in GE and Norland DXA?
K-edge filtering
170
Which detector/system is used in Hologic DXA?
Voltage switching
171
What do K-edge filtering systems use?
Constant-potential generator and a k-edge filter to split the polyenergetic x-ray beam into high and low energy components.
172
What type of filter does GE-Healthcare Lunar use?
Cerium filter that results in energy peaks of 40 and 70 keV.
173
What type of filter does Norland use?
A samarium filter that results in energy peaks of 45 and 80 keV.
174
What is pulse counting?
The energy discriminating detector counts the high and low energy photons at each image position.
175
How are high and low energy photons differentiated in a DXA machine?
With an energy discriminating detector.
176
Do photon counting systems have limited count rate capabilities?
Yes
177
What do voltage-switching systems use?
Switch the high-voltage generator, that is connected to the x-ray source, between high and low peak voltage (kVp) during alternate half-cycles of the main power supply.
178
Which system does not require differentiation of high and low energy photons in a DXA machine?
Voltage-switching system
179
What do current-integrating detectors do?
They sum all the signal during the half cycle since all the photons are either high (or low) photons.
180
Which system is better for low photon count rate?
K-edge filtering systems
181
How are voltage switching systems calibrating?
Continuously calibrated using a rotating wheel or drum (internal calibration)
182
Is the clinical utility affected by method of dual-energy production or type of detectors used?
No
183
Can clinical results between manufacturers be compared?
No
184
What two types of central DXA scanners are they?
- Pencil-beam
| - Fan-beam
185
Scanning occurs point by point.
Which type of scanner?
Pencil-beam scanners
186
Scanning occurs line by line.
Which type of scanner?
Fan-beam (or array) scanners
187
What two types of fan-beam scanners are there?
- Wide-angle fan-beam (oriented transverse to the long axis of the body)
- Narrow-angle fan-beam (oriented parallel to the long axis of the body)
188
Does Hologic use wide-angle or narrow-angle fan-beam?
Wide-beam
189
Does GE use wide-angle or narrow-angle fan-beam?
Narrow-angle fan-beam
190
Which one is cheaper...
Pencil-beam or fan-beam?
Pencil-beam
191
Which one has faster acquisition...
Pencil-beam or fan-beam?
Fan-beam
192
Which one has multiple detectors...
Pencil-beam or fan-beam?
Fan-beam
193
Which one is more accurate...
Pencil-beam or fan-beam?
They are comparable
194
Which one is more precise...
Pencil-beam or fan-beam?
They are comparable
195
Do pencil-beam scanners have a rotating gantry?
No
196
Which one has better resolution...
Pencil-beam or fan-beam?
Fan-beam
197
Which one has higher radiation dose...
Pencil-beam or fan-beam?
Fan-beam
198
Why are BMD values of different manufacturers not comparable?
(Five reasons)
Because of different:
- Methods of dual-energy production
- Calibration
- Detectors
- Edge detection software
- Regions of interest
199
Compared to central devices, SXA and peripheral DXA are:
Smaller or larger?
Smaller
200
Compared to central devices, SXA and peripheral DXA are:
Portable or non-portable?
Portable
201
Compared to central devices, SXA and peripheral DXA have:
Lower or higher radiation doses?
Lower radiation doses
202
Compared to central devices, SXA and peripheral DXA have:
Shorter or longer scan times?
Shorter scan times
203
Compared to central devices, SXA and peripheral DXA are:
Easier or harder to operate?
Easier to operate
204
Compared to central devices, SXA and peripheral DXA are:
Cheaper or more expensive?
Cheaper
205
What two types of peripheral DXA device configurations are there?
- Pencil-beam configuration
| - Cone-beam configuration
206
Do peripheral DXA use different normative databases?
Yes
207
Which one uses a water bath for soft tissue equalization...
SXA or DXA?
SXA
208
Which three parts of the body do peripheral DXA measure BMD in?
- Forearm
- Finger
- Heel
209
For QCT of the spine...
Can any commercial scanner be used?
Yes
210
For QCT of the spine...
Is addition of special software required?
Yes
211
For QCT of the spine...
Is the addition of a reference phantom usually required?
Yes
212
For QCT of the spine...
What is software used for?
To help place regions of interest within the vertebral bodies (usually L1-L3)
213
For QCT of the spine...
What is reference phantom used for?
It is used to convert CT attenuation coefficient (Hounsfield Units, HU) to bone equivalent values (BMD).
214
For QCT of the spine...
If systems don't require a phantom what do they use?
They use the patient's fat and muscle as standards.
215
Does DXA allow volumetric BMD measurement?
No
216
Does QCT allow volumetric BMD measurement?
Yes
217
Does size of vertebral body cause error in measurement when measured with QCT?
No
218
Which is better for patients who are at the extremes for size and weight...
DXA or QCT?
QCT
219
Which can measure purely cancellous bone...
DXA or QCT?
QCT
220
Which is less effected by degenerative disease of the spine...
DXA or QCT?
QCT
221
Which is more precise...
DXA or QCT?
DXA
222
Which has a higher radiation dose...
DXA or QCT?
DXA
223
How can the precision of QCT be improved?
With 3D (spiral CT)
224
Which method of measurement allows true volumetric BMD measurement of the forearm?
Peripheral QCT
225
Is separation into cortical and cancellous compartments of bone possible with pQCT?
Yes
226
Does pQCT require a dedicated scanner?
Yes
227
Which has a lower radiation dose spine/hip QCT or peripheral QCT?
Peripheral QCT
228
Does pQCT measure areal or volumetric measurement BMD?
Volumetric BMD
229
Which has greater technology diversity...
DXA or QUS?
QUS
230
How much radiation does QUS have?
None
| It's ultrasound
231
Does QUS measure BMD?
No
232
Is QUS used centrally or peripherally?
Peripherally
233
Does QUS work better with more or less soft tissue covering over site?
Less soft tissue covering
234
For QUS transmission:
What two types of sound transmission are there?
- Transverse sound waves (travels through bone)
| - Axial sound waves (travels along cortex of bone)
235
For QUS transmission:
Which machines use transverse sound waves?
- GE, Achilles
| - Hologic, Sahara
236
For QUS transmission:
Which machine uses axial sound waves?
Sunlight
237
For QUS transmission:
What types of systems are they for transducer coupling?
- Water-based systems
- Gel-based systems
- Systems that use both
238
How are regions of interest selected in QUS?
Imaging systems
239
Which two parameters does QUS measure?
- Speed of sound (SOS) in meters per second (m/sec)
| - Broadband ultrasound attenuation (BUA) of sound in decibels per megahertz (dB/MHz)
240
Are calculated parameters in QUS lower in normal patients or those with osteoporosis?
Those with osteoporosis
241
Correlation of QUS measurements with BMD by DXA.
Calcaneal BMD?
(r = ?)
Moderately high
r = 0.6 - 0.8
242
Correlation of QUS measurements with BMD by DXA.
Spine or hip BMD?
(r = ?)
Modest
(r
243
What is one explanation for QUS T-scores and central DXA T-scores not correlating well?
Different reference populations
244
How is accuracy defined in bone densitometry?
The ability of a measurement to match the accepted reference value.
245
What two types of error affect accuracy in densitometry?
- Systematic error (trueness)
| - Random error (precision)
246
What is systemic error?
% error between true and measured value
247
If there is systematic error will the average measurement value, from multiple measurements of the same person, be 'true' or 'untrue'?
Untrue
248
FDA 510K clearance requires less than ___% error of BMD devices.
10%
249
Is trueness more important for diagnosis or monitoring serial changes?
Diagnosis
250
What method is used to determine 'trueness'?
Bone ash method
251
What is precision?
Comparison between serial measurements if the same object or person.
252
Is the average value of random errors 'true' or 'untrue'?
True
253
Why is precision important?
For reproducibility
254
What is in-vitro precision best used for?
Monitor the stability of the system for quality assurance.
255
What is in-vivo precision best used for?
To determine when true change has occurred in serial measurements on the same individual
256
Least significant change is in-vivo precision.
True or false?
True
257
Trueness is most affected by...
Technology
258
Precision is most affected by...
Operator (technologist)
259
Central DXA:
PA spine...
Precision Error?
1 - 2%
260
Central DXA:
Lateral spine...
Precision Error?
2 - 3%
261
Central DXA:
Femur...
Precision Error?
1.5 - 3%
262
Central DXA:
Forearm...
Precision Error?
1%
263
Central DXA:
Total body...
Precision Error?
1%
264
Central DXA:
PA spine...
Trueness Error?
4 - 10%
265
Central DXA:
Lateral spine...
Trueness Error?
5 - 15%
266
Central DXA:
Femur...
Trueness Error?
6%
267
Central DXA:
Forearm...
Trueness Error?
5%
268
Central DXA:
Total body...
Trueness Error?
3%
269
Peripheral DXA:
Forearm...
Trueness Error?
4 - 6%
270
Peripheral DXA:
Calcaneus...
Trueness Error?
4 - 6%
271
Peripheral DXA:
Hand...
Trueness Error?
5%
272
Peripheral DXA:
Forearm...
Precision Error?
1 - 2%
273
Peripheral DXA:
Calcaneus...
Precision Error?
1 - 2%
274
Peripheral DXA:
Hand...
Precision Error?
1 - 2%
275
SXA:
Precision Error?
1 - 2%
276
Spine QCT:
Precision Error?
1.5 - 4%
277
Peripheral QCT:
Precision Error?
1 - 2%
278
Peripheral QCT:
Trueness Error?
2 - 8%
279
Spine QCT:
Trueness Error?
5 - 15%
280
SXA:
Trueness Error?
4 - 6%
281
Which has better precision...
SXA/DXA or QUS?
SXA/DXA
282
What has been proposed as a way to adjust for signal magnitude between x-ray and QUS devices?
Standardized precision error
283
What is radiation?
Flow of energy through space and matter, in the form of particles or waves.
284
What kind of radiation are x-rays?
Ionizing radiation
285
Do x-rays have short or long wavelength?
Short wavelength
286
Do x-rays have one energy level or multiple?
Multiple energy levels (polyenergetic)
287
What is the absorbed dose?
| Skin entry dose
Measurement if total amount of radiation entering the body.
288
May skin entry dose be expressed as entrance surface dose?
Yes
289
What units is skin entry dose/ absorbed dose expressed in?
gray (Gy) or rad
290
What is the effective dose or dose equivalent?
Calculated dose and calculates the potential biological harm radiation may have on the tissue after being absorbed.
291
What units is effective dose/ dose equivalent expressed in?
sievert (Sv) or rem
292
Is the effective dose / dose equivalent corrected for type of radiation and tissue sensitivity?
Yes
293
Which radiation dose is the correct method to check if your device is working within specifications...
Skin entry dose vs effective dose?
Skin entry dose
294
Where can you find the effective dose?
In published literature
295
Which is higher, skin entry dose or effective dose?
Skin entry dose
296
What is the probability of fatal cancer after radiation exposure?
1% per Sv
| 1 million DXA
297
What is the probability of severe genetic effects in succeeding generations after radiation exposure?
1% per Sv
| 1 million DXA exams
298
What is the risk of pre-implantation death and congenital anomalies (mental retardation) after radiation exposure?
Minimum dose of 100 mSv (100,000 DXA exams)
299
What are the two categories of biologic effects of radiation?
- Stochastic
| - Deterministic
300
Do stochastic effects of radiation occur at low dose or high dose?
Low dose
301
Do deterministic effects of radiation occur at low dose or high dose?
High dose
302
Do stochastic effects or deterministic effects of radiation cause an increase in random events?
Stochastic effects of radiation
303
Stochastic effects or deterministic effects of radiation?
Probability of occurrence is a function of dose.
Stochastic effects of radiation
304
Stochastic effects or deterministic effects of radiation?
Small risk, no threshold dose...
Stochastic effects of radiation
305
Stochastic effects or deterministic effects of radiation?
Occur in each individual receiving sufficient dose...
Deterministic effects of radiation
306
Stochastic effects or deterministic effects of radiation?
Examples: cancer and mutation
Stochastic effects of radiation
307
Stochastic effects or deterministic effects of radiation?
Examples: acute radiation sickness and cataracts
Deterministic effects of radiation
308
Stochastic effects or deterministic effects of radiation?
Threshold dose (1.2 - 3 Sv) below which effects are insignificant
Deterministic effects of radiation
309
Is the threshold dose for deterministic effects of radiation smaller or greater than doses used in medical imaging (including DXA and QCT)?
Much greater
310
Is the dose to patient from central DXA smaller or greater than doses from other radiological exams?
Much smaller (1/50th to 1/1000th of the dose)
311
At a distance greater than ___ meter away from the scanner table the radiation dose is negligible (no different than background).
1
312
What is the maximal permissible dose of radiation in the United States...
General public?
5000 microSv per year
| Excluding medical or dental
313
What is the maximal permissible dose of radiation in the International...
General public?
1000 microSv per year
314
What is the maximal permissible dose of radiation in the United States...
Occupational exposure?
50,000 microSv per year
315
What does ALARA stand for?
As low as reasonably achievable
| For radiation exposure
316
Intensity of radiation decreases as the square of distance away from source.
True or false?
True
317
What is used for safety in general radiology?
Shielding
318
How far should the technologist be from the edge of table of the DXA machine?
Greater than 1 meter
319
Patients should be pre-screened for contraindications for DXA exams.
True or false?
True
320
Should pregnant women get DXA scans?
No
321
Should a pregnant technologist be doing DXA scans?
What steps can be taken?
- Should notify employer and take precautions
- Reassignment of duties or shielding with lead apron
- Badge at abdomen to monitor fetal radiation
322
What is the permissible dose for a pregnant technologist?
5000 microSv for the duration of the pregnancy
Not to exceed 500 microSv per month
323
What two calibration methods are used as clinical quality control procedures?
- Internal (continuous)
| - External (periodic)
324
Which scanners use continuous calibration methods?
Hologic scanners
325
Which scanners use periodic calibration methods?
- GE-Healthcare Lunar
| - Norland
326
Periodic or continuous calibration?
X-ray passes through calibration filter (drum or wheel) while patient is being scanned.
Continuous calibration
327
Periodic or continuous calibration?
Calibration filter contains bone, tissue, and air equivalent.
Continuous calibration
328
Periodic or continuous calibration?
Point by point calibration.
Continuous calibration
329
Periodic or continuous calibration?
Daily scanning of known bone and tissue standards.
Periodic calibration
330
Periodic or continuous calibration?
Utilises a calibration standard.
Periodic calibration
331
Periodic or continuous calibration?
May automatically adjust calibration factors as needed.
Periodic calibration
332
How often are phantom scans recommended as an independent check of system quality assurance?
At least one per week
333
What three things may cause calibration shift?
- Relocation
- Maintenance
- Change of X-ray tube or detector
334
What three things may cause calibration drift?
- Change in room conditions (temperature, humidity)
- Change in power supply
- Aging of X-ray tube or detector
335
What should you do if you have upgraded your software between studies?
Reanalyse the baseline study with the new software before comparing it with follow-up study.
336
What should be done when changing hardware or when replacing with the same manufacturer and model?
Cross calibration should be performed.
337
How many phantom scans should one technologist do with repositioning before and after hardware change?
10
338
If after hardware changes and calibration there is more than __% difference in mean BMD, then the manufacturer should be contacted for service.
1
339
When does height loss begin?
In the mid 40s
340
What is the cumulative height loss by age 80 in males?
5 cm
341
What is the cumulative height loss by age 80 in females?
6.2 cm
342
Are clinical risk factors a substitute for BMD testing?
No
343
Do risk factors predict osteoporosis according to the IMPACT trial?
No
344
Is low BMD an independent risk factor for osteoporotic fractures?
Yes
345
Is advancing age an independent risk factor for osteoporotic fractures?
Yes
346
Is prior fracture an independent risk factor for osteoporotic fractures?
Yes
347
Is family history of osteoporosis or fragility fracture in a first degree relative an independent risk factor for osteoporotic fractures?
Yes
348
Is being a current smoker an independent risk factor for osteoporotic fractures?
Yes
349
Is low body weight an independent risk factor for osteoporotic fractures?
Yes
350
Are falls an independent risk factor for osteoporotic fractures?
Yes
351
Is sarcopenia an independent risk factor for osteoporotic fractures?
Yes
352
Is dementia an independent risk factor for osteoporotic fractures?
Yes
353
Are risk factors for low BMD the same as risk factors for fractures?
No
354
Decreasing BMD by 1 SD increases fracture risk by ____ times?
1.7 - 2.6
355
Each decade of aging past age 50 increases fracture risk by ___ times.
2
356
One prior vertebral fracture increases the risk of subsequent vertebral fracture by approximately ___ fold.
4
357
Is hypogonadism an indication for BMD measurement?
Yes
358
Does Medicare give early reimbursement for...
Estrogen-deficient women at clinical risk for osteoporosis (as determined by the physician)
?
Yes
359
Does Medicare give early reimbursement for...
Individuals with vertebral abnormalities. X-ray evidence of low bone mass / density or vertebral fractures
?
Yes
360
Does Medicare give early reimbursement for...
Individuals receiving glucocorticoid therapy (expected use over 3 months with 5 mg or more of prednisone or equivalent
?
Yes
361
Does Medicare give early reimbursement for...
Individuals with primary hyperparathyroidism
?
Yes
362
Does Medicare give early reimbursement for... And how often...
Individuals monitored for response on a FDA-approved osteoporosis drug therapy
?
Yes
One test every two years
363
Does Medicare give early reimbursement for...
Exceptions made when medically necessary such as patients on glucocorticoid therapy for more than three months or for baseline testing to allow monitoring if the initial test was performed with a different technique from the proposed monitoring method.
?
Yes
364
Do chronic inflammatory diseases cause bone loss in adolescents?
Yes
365
Do some endocrinopathies cause bone loss in adolescents?
Yes
366
Does a history of childhood cancer cause bone loss in adolescents?
It can
367
Does thalassemia major cause bone loss in adolescents?
Yes
368
When should you do BMD testing in children and adolescents with thalassemia major?
At fracture presentation or age 10 whichever earlier.
369
Should you do BMD testing in children and adolescents prior non-renal transplantation?
Yes
370
Does chronic immobilization (e.g. cerebral palsy) cause bone loss in adolescents?
Yes
371
What are the (relative) contra-indications for central DXA?
- Pregnancy
- Recent contrast study (spine DXA)
- Recent nuclear medicine scan (wait at least 72 hours after these studies)
- Extensive orthopedic instrumentation (measure a different site)
- Severe obesity (weight limits of 250 - 450 pounds)
372
What should you do if the patient is too obese for the central DXA scanner?
Measure forearm density
373
Name five endocrinopathies associated with low bone mass.
- Hyperparathyroidism
- Hyperthyroidism
- Cushing's Syndrome
- Hypogonadism (including hyperprolactinemia)
- Hypercalciuria
374
Are suppressive doses of thyroid hormone associated with low bone mass?
Yes
375
Is heparin associated with low bone mass?
Yes
376
Are GnRH agonists associated with low bone mass?
Yes
377
Is Depo-Provera associated with low bone mass?
Yes
378
Is phenytoin associated with low bone mass?
Yes
379
Are exchange resins associated with low bone mass?
Yes
380
Are thiazolidinediones associated with low bone mass?
In some women
381
Is excess vitamin A associated with low bone mass?
Yes
382
Is phenobarbital associated with low bone mass?
Yes
383
Is cyclosporine associated with low bone mass?
Yes
384
Is a gastrectomy associated with low bone mass?
Yes
385
Is inflammatory bowel disease associated with low bone mass?
Yes
386
Is celiac disease associated with low bone mass?
Yes
387
Is intestinal bypass surgery associated with low bone mass?
Yes
388
Is primary biliary cirrhosis associated with low bone mass?
Yes
389
Is pancreatic insufficiency associated with low bone mass?
Yes
390
Is rheumatoid arthritis associated with low bone mass?
Yes
391
Is systemic lupus erythematosus associated with low bone mass?
Yes
392
Is ankylosing spondylitis associated with low bone mass?
Yes
393
Is anorexia nervosa associated with low bone mass?
Yes
394
Is bulimia nervosa associated with low bone mass?
Yes
395
What is the female athlete triad?
- Disordered eating
- Menstrual irregularity
- Low bone mass
396
Name two drugs that cause vitamin D deficiency?
- Phenytoin
| - Phenobarbital
397
Is liver and kidney disease associated with vitamin D deficiency?
Yes
398
Is there an age-related decline in cutaneous production of vitamin D?
Yes
399
Do gastrointestinal diseases pre-dispose to vitamin D deficiency?
Yes
400
Is multiple myeloma associated with low bone mass?
Yes
401
Is hemolytic anemia, hemoglobinopathies associated with low bone mass?
Yes
402
Is myelo-and lymph-proliferative disorders associated with low bone mass?
Yes
403
Are skeletal metastases (diffuse or localized) associated with low bone mass?
Yes
404
Is Gaucher's disease associated with low bone mass?
Yes
405
Is mastocytosis associated with low bone mass?
Yes
406
Is Ehlers-Danlos syndrome associated with low bone mass?
Yes
407
Is Marfan's syndrome associated with low bone mass?
Yes
408
Is homocystinuria associated with low bone mass?
Yes
409
Is osteogenesis imperfecta associated with low bone mass?
Yes
410
What could you need a bone biopsy in the case of low bone mass / density?
To differentiate between osteomalacia and osteoporosis.
411
Which patients with low bone mass / density need a bone biopsy?
- Patients with unusual features of osteoporosis (young men and women with unexplained osteoporosis, patients with very low bone mass, patients with fragility fractures but normal BMD)
- Patients failing conventional therapy (non-responders)
- In renal osteodystrophy when osteomalacia is suspected
412
What are bone turnover markers?
Products of bone remodelling
413
Are bone turnover markers independent predictors for fracture?
Yes
414
Can bone turnover markers be used to diagnose osteoporosis?
No
415
What are the three markers of bone resorption?
- N-telopeptide (NTX) - serum or urine
- C-telopeptide (CTX) - serum or urine
- Deoxypyridinoline (free, total)
416
What are the markers of bone formation?
- Bone specific alkaline phosphatase
- Osteocalcin
- Procollagen Type I N-terminal Propeptide (PINP)
417
Bone turnover markers do not predict hip fracture independently of BMD.
True or false?
False
418
Bone turnover markers predict bone loss in recently post-menopausal women.
True or false?
True
419
Bone markers may predict response to estrogen therapy in recently menopausal women.
True or false?
True
420
How much bone loss must occur before low bone density is seen on x-rays?
About 30% or more
421
Which study should be done if fracture is equivocal?
MRI or bone scan
422
Which study should be done if fracture is suspected to be remote?
Bone scan or MRI
423
Which study should be done if kyphoplasty or vertebroplasty is being considered?
Bone scan and MRI
424
Which study should be done if metastatic carcinoma is a consideration?
MRI or biopsy
425
Which study should be done if neurological signs are present?
MRI
426
How do you diagnose fractures of the mobile type?
By comparing standing lateral radiographs with supine cross-table lateral films.
427
In which view can you see dynamic mobile fractures?
Standing lateral films
428
What is 'Kummels sign'?
Intervertebral clefts associated with dynamic mobile fractures caused by osseous necrosis.
429
What does Kummels sign look like on conventional radiographs?
Vacuum phenomenon
430
What does Kummels sign look like on MRI?
Signal void
431
What percentage of vertebral fractures necessitate admission to the hospital?
10%
432
Only about ____ of vertebral fractures found on radiographs come to medical attention.
One-third
433
About what percentage of vertebral fracture events are asymptomatic?
About 50%
434
Presence of vertebral fractures are a strong indication for pharmacologic therapy.
True or false?
True
435
The greater the number of prevalent vertebral fractures, the greater the risk of future fractures.
True or false?
True
436
The greater the severity of prevalent vertebral fractures, the greater the risk of future fractures.
True or false?
True
437
Pre-existing vertebral fractures predict future fractures independent of BMD.
True or false?
True
438
VFA can diagnose fractures at the time of DXA.
True or false?
True
439
Which visual technique is used in VFA...
Qualitative or quantitative?
Qualitative
440
What does the term 'Vertebral Fracture Assessment' denote?
Densitometric spine imaging performed for the purpose of detecting vertebral fractures.
441
What three types of vertebral fractures are there?
- Wedge
- Biconcave
- Crush
442
What are the three ways of diagnosing and grading vertebral fractures?
- Qualitative (visual inspection)
- Semiquantitative (visual inspection with assignment of fracture grade)
- Quantitative (morphometry)
443
What are the three grades of fractures according to the Genant's chart?
- Mild fracture/Grade 1 ~ 20 - 25%
- Moderate fracture/Grade 2 ~ 25 - 40%
- Severe fracture/Grade 3 ~ 40% or more
444
What is the main advantage of VFA?
It can be performed during the visit for DXA and the BMD information and fracture status can be integrated.
445
Spine x-ray or VFA...
Which has a higher radiation dose?
Spine x-ray
446
Spine x-ray...
Radiation dose?
1800 - 2000 microSv
447
VFA...
Radiation dose?
30 - 50 microSv
448
Spine x-ray or VFA...
Which has better access?
VFA
449
Spine x-ray or VFA...
Which has a higher cost?
Spine x-ray
450
Spine x-ray or VFA...
Which has a higher resolution?
Spine x-ray
451
Spine x-ray or VFA...
Which has better visualization above T7?
Spine x-ray
452
Spine x-ray or VFA...
Which has more parallax effect?
Spine x-ray
453
Spine x-ray or VFA...
Which has automated morphometry?
VFA
454
What is the gold standard for vertebral fractures?
Spine x-rays
455
What is the sensitivity of VFA for moderate and severe fractures?
90 - 94%
456
What is the sensitivity of VFA for mild fractures?
50%
457
What is the negative predictive value of VFA?
Over 95%
458
Name four confounding factors in VFA interpretation.
- Severe scoliosis
- Bowel gas
- Aortic calcification
- Rib and scapular shadows
459
Name three internal or external artifacts in VFA interpretation.
- Surgical hardware
- Implanted devices
- Bra clips, zippers, buttons
460
What is the definition of a vertebral fracture according to Genant's SQ system?
20% reduction in vertebral height
461
When should VFA be considered?
When the results may influence clinical management
462
VFA should be considered if there is documented height loss > ___ or historical height loss > ___ since young adulthood.
```
2 cm (0.75 inches)
4 cm (1.5 inches)
```
463
Can patients with normal BMD have osteoporotic fractures?
They may.
464
Why did the WHO chose T = -2.5?
This cut off value identifies ~ 30% of post menopausal women as having osteoporosis at the spine, hip or forearm.
465
What's the lifetime risk of fracture at the spine, hip or forearm?
30%
466
What is the Z-score?
Number of standard deviations the patient's BMD is above or below age and sex-matched mean reference value.
467
Are Z-scores used for diagnosis in adults?
Yes
468
Is there any evidence to support a specific cut-off point for Z-scores after which you evaluate for secondary causes?
No
469
What would using Z-score for diagnosis of osteoporosis suggest?
That the prevalence of osteoporosis does not increase with age - this is not true.
470
Can BMD be used across all devices?
No
471
Can T-scores be used across all devices?
Yes
472
Can the lateral spine be used for diagnosis of osteoporosis?
No
473
Should Ward's area be used for diagnosis?
No
474
Should greater trochanter be used for diagnosis?
No
475
What is the region of interest in the forearm?
Distal 1/3 radius on the non-dominant forearm.
476
Using DXA young normal men have BMD ~ ____% higher than women (mostly because they have larger bones)
10
477
Men fracture at the hip at a higher bone density than women.
True or false?
False
They fracture at the same BMD
(Data controversial)
478
Men fracture at the spine at a higher BMD than women.
True or false?
True
| Data controversial
479
Using DXA young normal blacks have BMD ~ ____% higher than whites.
10
480
Asians have similar bone density to whites.
True or false?
True
481
Some manufacturers adjust their T-scores for race while others do not...
Hologic?
Adjusts for men and women
482
Some manufacturers adjust their T-scores for race while others do not...
Norland?
Adjusts in women but not in men
483
Some manufacturers adjust their T-scores for race while others do not...
GE-Lunar?
Does not adjust
484
Some manufacturers adjust their T-scores for race while others do not...
Which machine does not adjust Z-scores in men?
Norland
485
What is the absolute risk?
Number of events over a defined period of time
486
What is relative risk?
Ratio of absolute risks of two different groups
487
Relative risk of fracture for 1 SD decrease in BMD (age-adjusted):
Site: Distal radius
Hip fracture?
1.8
488
Relative risk of fracture for 1 SD decrease in BMD (age-adjusted):
Site: Distal radius
Vertebral fracture?
1.7
489
Relative risk of fracture for 1 SD decrease in BMD (age-adjusted):
Site: Proximal radius
Hip fracture?
2.1
490
Relative risk of fracture for 1 SD decrease in BMD (age-adjusted):
Site: Proximal radius
Vertebral fracture?
2.2
491
Relative risk of fracture for 1 SD decrease in BMD (age-adjusted):
Site: Calcaneous
Hip fracture?
2
492
Relative risk of fracture for 1 SD decrease in BMD (age-adjusted):
Site: Calcaneous
Vertebral fracture?
2.4
493
Relative risk of fracture for 1 SD decrease in BMD (age-adjusted):
Site: Spine
Hip fracture?
1.6
494
Relative risk of fracture for 1 SD decrease in BMD (age-adjusted):
Site: Spine
Vertebral fracture?
2.3
495
Relative risk of fracture for 1 SD decrease in BMD (age-adjusted):
Site: Femoral neck
Hip fracture?
2.6
496
Relative risk of fracture for 1 SD decrease in BMD (age-adjusted):
Site: Femoral neck
Vertebral fracture?
1.8
497
What is the best measure of the strength of the association between a risk factor and a disease outcome?
Relative risk
498
What does a relative risk of 1 mean?
Either:
- Absolute risk of both groups is the same
OR
- There is no association between the risk factor and the disease
499
BMD at any site can predict fracture risk.
True or false?
True
500
What happens to lifetime risk of fractures with age?
It decreases because life-expectancy decreases.
501
In Rochester, a hip fracture predicted a ___% risk of a contralateral hip fracture over ___ years.
29%
| 20 years
502
What is the average lifetime risk of hip fracture in men?
6%
503
What is the average lifetime risk of hip fracture in women?
17%
504
Fracture risk increases _____ gold for each SD decrease in BMD.
1.5 - 3
505
Is FRAX absolute or relative risk?
Absolute risk
506
Precision - Manufacturer's range...
PA spine?
0.5 - 1.5%
507
Precision - Manufacturer's range...
Total hip?
0.5 - 1.5%
508
Precision - Manufacturer's range...
Femoral neck?
1 - 2.5%
509
Precision - Clinical Center's range...
PA spine?
1 - 2.5%
510
Precision - Clinical Center's range...
Total hip?
1.5 - 2.5%
511
Precision - Clinical Center's range...
Femoral neck?
2 - 3.5%
512
What does %CV stand for?
Percentage coefficient of variation
513
Does total body BMD respond well to therapy?
Yes
514
What is the desirable level of serum 25-OH vitamin D?
30 - 60 ng/mL
515
What is the prophylactic dose of alendronate?
35 mg per week
Or
5 mg per day
516
What is the treatment dose of alendronate?
75 mg per week
Or
10 mg per day
517
Dose of Ibandronate, over what period of time?
3 mg IV over 15 - 30 seconds
518
How long can you treat with teriparatide for?
2 years
519
What does teriparatide do to bone markers?
Increases bone markers
520
Which DXA machine has a One-Scan option that uses a correction factor to compensate for the change in position?
GE-Lunar
