Bone Densitometry

1
Bone Densitometry

• Interpretation of DEXA

2
Osteoporosis
3
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.

4
Osteoporosis

• Type 1. involutional osteoporosis affects mainly
  trabecular bone, occurs in women during the 15-20
  years after the menopause, and is related to a
  lack of estrogen. This is thought to account for
  wrist and vertebral crush fractures, which occur
  through areas of principally trabecular bone.
• Type 2. senile involutional osteoporosis. The
  fractures of old age seen at the hip, proximal
  humerus, pelvis and asymptomatic vertebral wedge
  fractures. This affects both trabecular and
  cortical bone and represents progressive loss of
  bone mass from the peak around the age of 18-35
  years.
• Secondary osteoporosis is due to an underlying
  medical condition, such as renal disease,
  malabsorption, or hormonal imbalance, or to
  medical treatment such as steroids or certain
  anticonvulsants

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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
• Small frame

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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 afterwards

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Osteoporosis
Osteoporosis progression over 2Y UC Steroids
59F
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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
  parameter

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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 Research
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Measurement
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Osteoporosis Measurement

• Plain film,
• Subjective, Radiogrammetry, Osteogram
• SPA
• DPA
• DEXA
• QCT
• US
• MRI

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Osteoporosis Measurement

• Plain film,
• Subjective, Radiogrammetry, Osteogram
• SPA
• DPA
• DEXA
• QCT
• US
• MRI

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Osteoporosis Measurement

• Plain film,
• Subjective, Radiogrammetry, Osteogram
• SPA
• DPA
• DEXA
• QCT
• US
• MRI

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Osteoporosis Measurement

• Plain film,
• Subjective, Radiogrammetry, Osteogram
• SPA
• DPA
• DEXA
• QCT
• US
• MRI

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Osteoporosis Measurement

• Plain film,
• Subjective, Radiogrammetry, Osteogram
• SPA
• DPA
• DEXA
• QCT
• US
• MRI

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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/cm2

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DEXA
y
x
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DEXA

• DEXA has very high
• accuracy
• (the difference in the measurement from a known
  standard)
• and
• precision
• (observed deviation of serial measurements with
  time)
• both short and long term
• to within 1 at the hip and spine

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DEXA

• DEXA is at present the most precise measurement
  of BMD
• QCT is more sensitive to change

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DEXAInterpretation
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DEXAInterpretation
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Find out as much relevant information as
possible
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Find out as much relevant information as
possible
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SpineScan
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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 tissue

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Vertebroplasty
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Calcium Tablets
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Transitional vertebrae
Wrong levels
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Bone DensitometryDEXA spine check list

• Look for significant level to level variations
• 15-20 difference between adjacent levels

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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.

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Common problems with spine scans.

• Spine isnt straight.
• Scan starts in sacrum.
• Scan stops too soon.
• Wrong scan mode.
• Scan doesnt include L5.

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What is a scan mode?

• This determines the speed the arm travels, and
  how much radiation the patient receives.
• The bigger the patient, the more radiation youll
  require.
• The smaller the patient, the less radiation
  youll require.

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IQ Scan Modes
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IQ Patient Thickness

• 12-15 cm is Medium 750
• 15-22 cm is Fast 3000
• 22-30 cm is Medium 3000
• Most patients fall in the Fast 3000 range.

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Bone Densitometry

• In preventing Fxs it is the worst scenario that
  matters.
• Generally a slight increase in density as descend
  the L spine.
• Approx 6 increase between L1 and L4.

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Typical Spine scan
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Whats wrong with this scan?
L1 is really T12
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Whats wrong with this scan?
Divisions dont account for scoliosis
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Whats wrong with this scan?
Everything
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FemurScan
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DEXA Femur check listHints for a good scan.

• Patient should be straight on table.
• Pack patient with rice bags.
• Shaft of femur should be straight.
• Rotate leg inward, this will hide the lesser
  trochanter.

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DEXA Femur check listHints for a good scan.

• The Wards area is roughly half the neck area
• Trochanteric area 8-14cm2 in women, 10-16cm2 in
  men
• Check left and right and state side being used in
  report.

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nonIQ DPX scanning

• Show 15-30 scan lines prior to seeing ischium.
• There should be little or no lesser Trochanter.
• Straight shaft.
• 25 lines or more above the Greater Trochanter.

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Typical Femur Scan
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Whats wrong with this scan?
Too much shaft
46
Whats wrong with this scan?
Insufficient tissue below neck
47
Whats wrong with this scan?
Set up for wrong leg
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Whats wrong with this scan?
Includes ischium
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Reporting
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Bone DensitometryWHO uses T scores

• Normal
• gt -1 SD below young adult
• Osteopenia
• -1 -2.5 SD
• Osteoporosis
• lt-2.5 SD
• Established (Manifest) Osteoporosis
• Fxs, usually spine, hip, proximal humerus,
  wrist, rib

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007179 - Macro DEXA
Template
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Bone Densitometry

• Never round up figures
• -1 is osteopenia, -0.99 is normal
• -2.5 is osteoporosis, -2.49 is osteopenia

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Example
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Bone Densitometry
44F
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Bone Densitometry
44F
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Bone Densitometry
44F
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Bone Densitometry
44F
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Bone Densitometry

• T score is compared to reference population,
  20-45 years, same sex, any race, any weight.
• Z score is matched for age, sex, weight and
  ethnicity.

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Two possible reasons for this ladys Z score
being worse than the T score?
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Two possible reasons for this ladys Z score
being worse than the T score? Obesity and race
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The T score is based on a white, same sex, age
20-40population. The patient's BMD is compared
to this population's BMD.A lower T score means
that the patient BMD is low compared to this
young, healthy normal weight population. The Z
score compares the patient to an adjusted
population, it adjustsfor age, weight, and
ethnic background. The Z score can be lower than
the T score for the patient, if the average
patient in this population has a higher BMD than
the average in the T score population. This can
be seen in patients with higher weights, (which
increases bone density), and in African American
groups, (which show increased bone density). If
the patients comparison group has a generally
higher bone density, then it is possible to have
a poorer comparison to others of same age, than
to younger comparisons in generally lower density
group.
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260 lb man, young Z above young T
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Black as Black
Black as White
64
Black as Black
gt
Black as White
T same Z up
lt
65
Bone DensitometryWeight gain/loss and Z

• Weight gain (or loss) will not affect Z score
  comparison, since Z scores are weight matched,
  but should cause an increase (or decrease) in
  absolute BMD.
• An increase in weight, pushes up the reference
  range, and therefore the Z score may seem
  reduced, and vice versa.

2.2lbs1Kg
66
Bone DensitometryWeight gain/loss and T

• Weight gain (or loss) should cause an increase
  (or decrease) in absolute BMD.
• Weight gain (or loss) will affect T score
  comparison, since reference range will not have
  changed.
• Hence an increase in weight with a corresponding
  increase in bone density, will look like a good
  improvement in T score, but fracture risk is
  unchanged.

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51F 90Kg
53F 51Kg
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1.172
1.176
SD 0.1 Both between -2 and -3 SD below
mean for age
1Y, 16lb gain, 5 BMD loss significant increase
in fracture risk
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Comparison with previous
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Bone DensitometryComparison with previous

• Are the studies comparable
• Always compare like with like
• Thornton L1-4
• 4th and Lewis (previously L2-4)
• Any intervening events
• Cannot compare Hologic and Lunar

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Bone DensitometryComparison with previous

• David Sartoriss previous studies that do not
  mention the region or levels measured, were
  standardized for L1-4 and the femoral neck.
• He usually did not quote BMD.
• Many previous studies were prior to the current
  database.
• Use the percent young adult as a guide to
  percentage change.

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Bone DensitometryComparison with previous

• If over a period of time there is an increase in
  BMD in the lower lumbar spine and decrease in the
  upper lumbar spine, it is likely there is OA of
  the lower facet joints, and the upper lumbar
  spine is a truer reflection of useful BMD.

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Bone DensitometryComparison with previous

• Increase in BMD of the femoral neck can be due to
  calcar buttressing with OA of the hip.

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Bone DensitometryComparison with previous

• If you want to eyeball the for a comparison,
  use the young adult since the reference range
  will not change with age.
• A static bone density is actually a good result
  over a significant period of time
• If a test is 1 precise, then a change has to be
  greater than 2 to be significant

75
Bone DensitometryComparison with previous

• If you would have expected the bone density to
  have fallen 4 in 2 years, and it is static, then
  this is a positive response to RX

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Bone DensitometryComparison with previous

• Generally Rx affects all levels equally.
• OA does not.

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Bone DensitometryComparison with previous
55F
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Bone Densitometry
55F
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Bone Densitometry
55F
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Bone Densitometry
55F
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Children
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Bone mass in healthy children
Radiology 1991179735-738
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Bone mass in healthy children

• Increases with age, weight and pubertal Tanner
  stage.
• Tanner stage and weight are best predictors of
  bone mass.
• Age, sex, race, activity and diet are not good
  predictors, when weight and Tanner stage are
  controlled.

Radiology 1991179735-738
84
Bone mass in healthy children

• Make sure we have at least the age and weight of
  the child, if not the Tanner stage.

Radiology 1991179735-738
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BMD in children and adolescents
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BMD in children and adolescents
BMD in children and adolescents- Female- L2-4-
Lunar
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BMD in children and adolescents
BMD in children and adolescents- Male- L2-4- Lunar
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BMD in children and adolescents- Female- femur
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BMD in children and adolescents- Male- femur
90
BMD in children and adolescents- Female- femoral
neck
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BMD in children and adolescents- Male- femoral
neck
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BMD in children and adolescents- Female- L2-4
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BMD in children and adolescents- Male- femur
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Cases
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Cases
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New Case
63F
6
97
63F
5
98
63F
4
99
63F
3
100
63F
2
101
Report

• Because of the previous laminectomy at L4, which
  may also be affecting the reading on the inferior
  aspect of L3, the BMD is averaged at L1-2. Note
  is also made of mild decrease in the L4 vertebral
  height.

1
63F
102
NewCase
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New Case
35F White 242lbs 62in
3
104
35F White 242lbs 62in
2
105
Report

• Because of the patients weight, the T score may
  not fully represent the fracture risk, and note
  should be made that the Z score is 1.7 SD below
  age and weight matched.

35F White 242lbs 62in
1
106
NewCase
107
New Case
2
OGI
39M
108
Report

• The very low bone density is compatible with the
  known diagnosis of osteogenesis imperfecta.

1
39M
109
NewCase
110
New Case
46 F
4
111
Calcified bile
46 F
3
112
2
46 F Calcified bile
113
Report

• Although the calcified bile is seen on the DEXA
  scan, it is outside the measured region and will
  not affect the reading.

1
46 F Calcified bile
114
NewCase
115
New Case
Black
47F
2
116
Report

• The Z score is worse than the T score at all
  levels because the the Z score is compared to
  weight and ethnicity and African American
  females naturally have a higher bone density than
  the standard Caucasian used for the T score, even
  at the age of 47.

1
African American 47F
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NewCase
118
New Case
49F 2Y8M gap Lx spine up, Fem neck down
2
119
Report

• A common cause for the bone density of the lumbar
  spine to increase whilst that of the femoral neck
  decreases over time is, the development of lower
  lumbar spine end plate sclerosis and facet
  osteophytes.

1
49F 2Y8M gap Lx spine up, Fem neck down
120
NewCase
121
New Case
T
Sacral agenesis
49F
2
122
Report

• It is likely that only L1 represents close to
  true bone density and use of femoral neck
  measurements alone is recommended.

1
Sacral agenesis 49F
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NewCase
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New Case
Dense R femoral neck
50F
3
125
50F dense R femoral neck
2
126
Report

• In view of the significant discrepancy between
  the right femoral neck and lumbar spine
  measurements , radiographs of the right
  hip/pelvis are recommended.

1
50F dense R femoral neck
127
NewCase
128
New Case
2d earlier
2d later
51F
3
129
51F Barium in diverticulum from recent enema
2
130
Report

• It was noticed that the patient has had a recent
  barium study and that barium may therefore
  falsely elevate the bone density. A repeat study
  is therfore recommended.

1
51F Barium in diverticulum from recent enema
131
NewCase
132
New Case
53F 51Kg
6 yr later, 8Kg wt loss
47F 59Kg
2
133
53F 51Kg
47F 59Kg
1
134
Report

• As the patient loses weight the T score worsens
  at a faster rate than the Z score because the
  reference range for the Z score also is lowered.
  
• However with the loss of weight the fracture risk
  does not increase as much as the T score worsens.

1
6 yr later, 8Kg wt loss
135
NewCase
136
New Case
60F
3
137
2
60F OA
138
Report

• Because of lower lumbar spine degenerative
  changes the lumbar spine should not be included
  in the study.

1
60F OA
139
NewCase
140
New Case
54M ESLD s/p trans
Rec. repeat
3
141
New Case
54M ESLD s/p trans
Rec. repeat
2
142
Report

• Only technical error could account for such a
  finding and therefore repeat study is recommended.

1
54M ESLD s/p trans
143
NewCase
144
New Case
15m earlier
15m later
76F response to Rx
2
145
Report

• If all levels increase in bone density over time,
  it is likely a response to treatment.

1
76F response to Rx
146
NewCase
147
New Case
85M Bil THR
3
148
85M Bil THR
2
149
Report

• When the lumbar spine and hips cannot be used we
  turn to the distal radius and use the ultradistal
  measurement.

1
85M Bil THR
150
NewCase
151
New Case
DEXA 51F
4
152
DEXA 51F
3
153
DEXA 51F
2
154
Report

• Increase in lumbar spine bone density is due to
  syndesmophytes and ligament ossification.

1
Ank Spond DEXA 51F
155
NewCase
156
New Case
59M
2
157
Report

• Calcium anterior to the spine can increase
  apparent BMD.

1
DEXA pancreatic Cal 59M
158
NewCase
159
New Case
50M
2
160
Report

• If the patient does not wish to divulge their
  personal details, only T score and not Z score
  can be produced.

1
DEXA no personal data 50M
161
NewCase
162
New Case
59F
4
163
59F
3
164
2
165
Report

• Benign bone sclerosis such as Worths disease or
  Van Buchems, or a variant of osteopetrosis.
• Recommend repeat DEXA to check for spurious
  result.

1
High bone density 8SD 59F
166
NewCase
167
New Case
62F
4
168
62F
3
169
MDP
62F
2
170
Report

• Benign sclerotic lesion L1
• Levels may be incorrect.

1
171
NewCase
172
New Case
76F
173
76F
174
Report

• When a vertebrae collapses, initially it will be
  of higher density.

1
DEXA L1 fracture 76F
175
NewCase
176
New Case
65F
177
65F
178
1Y prior
2m prior
DEXA with islet cell met to L2 65F
179
Report

• Look out for vertebrae with a different and
  unaccountable bone density, either higher or
  lower.

1
DEXA with islet cell met to L2 65F
180
NewCase
181
New Case
44F
182
44F
183
Report

• 52, 182lbs

1
184
NewCase
185
New Case
55F
186
Report
1
55F
187
55F
188
Report

• Good response to Rx

1
189
New Case
54yo F with h/o pancreatic neuroendocrine tumor
and small cell lymphoma on Fosamax
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NewCase
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Report
1
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Bone DensitometryDEPA

• Gd153
• Accuracy similar to QCT
• Less radiation than QCT
• Measures cortical and trabecular
• Less sensitive to early changes
• Affected by aortic Ca2

201
DPX-IQ scanning

• Show 25-40 scan lines prior to seeing ischium.
• There should be little or no lesser Trochanter.
• Straight shaft.
• 25 lines or more above Greater Trochanter.

202
Bone DensitometryQCT

• Single energy 97 accurate
• Dual energy not routinely available
• 300mR
• Fat content adversely affects accuracy
• Difficult to reproduce positioning
• Can only measure trabecular bone
• 8X increase turnover of trabecular bone

203
IQ has version 4.3 and above
204
Non IQ has these versions

• Version 1.15 for the DPXalpha
• Version 1.35 for the DPXL
• Version 3.65 for the DPX
• Version 1.15 for the DPXSF
• Can upgrade with the 3.65 u on all versions.

205
DPXIQ versus DPXnonIQ

• Spine measure and analysis are the same.
• Scan modes vary depending on the type of DPX.
• Femur measuring is different.
• Femur analyzing is different.
• IQ and nonIQ are different animals.

206
How is IQ different?

• IQ offers unlimited patients in database
• IQ offers Total Femur results, as well as Femoral
  Neck.
• IQ offers better resolution image.
• IQ offers automatic analysis of femurs.
• IQ offers better algorithms for femurs.

207
How is nonIQ different?

• Limited patients in database (3500 to 7500).
• Offers only Femoral Neck
• Resolution is not nearly as good.
• Must manually analyze all femurs.
• Algorithms not as good for femurs.

208
SPINE SCANS FOR ALL TYPES OF DPX
209
IQ and non IQ, 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.

210
Common problems with spine scans.

• Spine isnt straight.
• Scan starts in sacrum.
• Scan stops too soon.
• Wrong scan mode.
• Scan doesnt include L5.

211
nonIQ Scan Modes

•  

212
Femur scans for DPX-IQ
213
Hints for a good scan.

• Patient should be straight on table.
• Pack patient with rice bags.
• Shaft of femur should be straight.
• Rotate leg inward, this will hide the lesser
  Trochanter.

214
DPX-IQ scanning

• Show 25-40 scan lines prior to seeing ischium.
• There should be little or no lesser Trochanter.
• Straight shaft.
• 25 lines or more above Greater Trochanter.

215
nonIQ DPX scanning

• Show 15-30 scan lines prior to seeing ischium.
• There should be little or no lesser Trochanter.
• Straight shaft.
• 25 lines or more above the Greater Trochanter.

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