deel 3 deel 4

2-69
T-score and Z-score
Compare patient BMD to reference values
BMD
(g/cm 2)
1.100
Peak Bone Mass = 1.047
1.050
AGE
20
25
30
35
40
45
50
55
60
65
70
80
85
Fem ale
1.019
1.040
1.047
1.041
1.024
0.999
0.967
0.930
0.892
0.854
0.815
0.752
0.731
1.000
0.950
0.900
T=-3,1
0.850
0.800
0.750
Z=-0,4
0.700
BMD = 0.700
0.650
AGE = 80
0.600
20
30
40
50
60
70
80
Reference Curve, Female total lumbar spine : SD = 0.11
90
AGE
2-70
Principe van de densitometrie
Absorptie van X-stralenbundel
2-71
Absorptiometry
Absorptie van fot onen (γ- or X-rays)
hangt af van
– Materie: i.e. Dichtheid
– Dikte
– Foton of X-ray energie
Vereenvoudigde patient bestaat uit twee
onbekenden:
bot en (zacht) weefsel
Absorptiemetingen met één energie geven
niet genoeg informatie om weefsel van
bot te onderscheiden.
Introductie van een extra factor:
two energies
DEXA
2-72
DXA Principle of Operation
A = Attenuatie per energieniveau
K = Correctiefactor voor de attenuatie in
zacht weefsel
A High Energy
ALow Energy
K*AHigh Energy
ALow Energy - K*AHigh Energy
Dual Energy Subtraction (BMD)
Image
2-73
Werkingsprincipe
Detector Array
X-Ray Fan
Beam
Object of Interest
Table Mat
Calibration
wheel
Tank
(X-Ray Source)
Table Top
Detectie
Intern calibratie w iel, gesynchronis eerd
met gepulste Dual Energy.
Calibratie w iel bevat drie gekende
segmenten :
1.Lucht
2.Weefseldata-punten voor iedere pixel in
het beeld
3.Bot
Ieder segment is gescand met Hoge
en Lage energie Dit levert zes
Interne Calibratie
1. Opwekken van X-stralen
2-74
Automatische Calibratie
Gepatenteerd Intern Referentie Systeem
• De continue calibratie per pixel vergelijkt
het “bekende” met het “onbekende”
Lucht = patient gemeten
Bot = botequivalent+ patient
Weefsel = weefselequivalent+ patient
• Verzekert compatibiliteit en
vergelijkbaarheid van data
• Verzekert stabiliteit op lange termijn
• Garandeert stabiliteit bij upgrades
• Gecontroleerd met automatische dagelijkse
QC dmv een QC fantoom.
2-75
Quantitative Ultrasound
2-76
Transverse Transmission
Broadband Ultrasound Attenuation
Speed of Sound
SOS
Healthy
Osteoporotic
Absorption
BUA
Time
Frequency
Calcaneus
Heel
Transmitter
waterbath
Receiver
2-77
Quantitative Ultrasound
Clinical Use
• Diagnosis of osteoporosis not possible
• WHO criteria not applicable
• Assessment of fracture risk possible (>60 to 65 years of
age) similar to DXA
• Use of threshold values DXA
• Large variability not suitable for follow-up / assessment
of treatment efficacy
2-78
Nieuwe “Explorer” serie Toestel
Gebruik
2-79
Positionering Lumbale wervelzuil
AP Lumbar spine
2-80
AP Spine
2-81
Positionering Heup
Hip Scan
2-82
AP Femur
2-83
2-84
Voorarm
2-85
Why Measure Spine and Hip
• Spine: trabecular, postmenopausal
• Hip: cortical, elderly
• Spine-Hip discordance
- find lower BMD site
• Fracture prediction
- spine BMD for spine fractures
- hip BMD for hip fractures
• Flexibility in monitoring
- with spine degenerative
disease, may use hip
2-86
Hip-Spine Discordance
PA Lumbar spine (T-score)
5
4
3
2
1
0
-1
-2
-3
-4
-5
-5
-4
-3
-2
-1
0
1
2
Femoral neck (T-score)
Arlot M. et al, J Bone Miner Res 1997; 12:683
3
2-87
Hip-Spine Discordance due to Vertebral
Fracture and Spinal Degenerative Disease
L2-L4
T = -0.2
WHO = Normal
Femoral neck
T = -2.7
WHO= Osteoporosis
2-88
Hip-Spine Discordance due to Early
Menopausal Trabecular Bone Loss
2-89
IRIS:
Integrated Radiology Information System
• Modality Worklist
• DIC OM 3 Image Storage
• Remote Softcop y Interpreta tion
• Electronic Report Generation
2-90
Dose Considerations
2-91
Dose considerations
Pencil beam
Fan beam
PA spine
0,5 µSv
2,0 µSv
Femur excl ovaries
0,1 µSv
0,6 µSv
Femur incl. ovaries
1,4 µSv
5,4 µSv
Scatter dose at 1 m:
under 1 μSv/h
Comparison:
• natural background:
about 1 mSv
(1 h ≈ 60 scans)
2-92
WHO Criteria for
Postmenopausal Osteoporosis
The T-score compares an individual’s BMD with the
mean BMD value for a young reference population, and
expresses the difference as a standard deviation score.
T-score
Normal
- 1.0 and above
Osteopenia
- 1.0 to - 2.5
Osteoporosis
- 2.5 and below
Severe (established) osteoporosis
- 2.5 and below, plus one or more
osteoporotic fracture(s)
Kanis J.A. et al, J Bone Miner Res 1994; 9:1137-41
2-93
Prevalence of Osteoporosis in
Women at Different Skeletal Sites
60%
Prevalence
50%
T-score ≤ -2.5
40%
30%
20%
10%
0%
Spine
50-59
Hip
60-69
Mid-radius
Melton et al, J Bone Miner Res 1995; 10:175
70-79
Any site
80+
age 50+
Years
2-94
Bone Density and Fracture Risk
±2 SD
35
32
30
sRR = 2
BMD
2-Fold Change in Fracture Risk / SD
Standardizing Risk Ratios
25
20
16 15
60
1 SD
8 10
70
Age
5
0
-5
-4
-3
-2
T-score
-1
0
80
2-95
Gradients of Risk
Relative risk
12
10
BMD & hip fracture
8
BP & stroke
6
Cholesterol & MI
4
2
0
I
II
III
Quartile
IV
2-96
WHO Criteria
Limited to Specific Populations,
Skeletal Sites, and Devices
• Only postmenopausal white women
- not men, younger women, other ethnic groups
• Only PA spine, hip (and forearm) DXA
- not lateral spine, heel, finger, etc
• Only for central DXA
- not peripheral DXA, QCT, QUS, RA, etc
2-97
Diagnosis in Men
• WHO´s diagnostic criteria may be used
- BMD related to the risk of bone fracture
- fracture risk increases ≈ 2 fold per 1SD
reduction in BMD ( similar to the risk found in
women )
• All manufacturers use gender specific T-scores
- at the same BMD, T-scores are different
depending on gender
- best approach for now
2-98
Risk Factors that Provide Indications
for the Diagnostic Use of Bone
Densitometry
1.
Radiographic evidence of osteopenia or vertebral deformity, or both
2.
Previous fragility fracture
3.
Loss of height, thoracic kyphosis
(after radiogra phic confirmation of vertebral deformities)
4.
Presence of strong risk factors:
• Anorexia nervosa
• Malabsorption
• Primary
•
•
•
•
•
hyperparathyroidism
Post-transplantation
Chronic renal failure
Hyperthyroidism
Prolonged immobilization
Cushing’s syndrome
Kanis J., Lancet 2002; 359:1929
•
•
•
•
•
•
•
•
Estrogen deficiency
Corticosteroid therapy
Premature menopause, < 45 yr
Maternal family history of hip fracture
Long-term secondary amenorrhea (> 1 yr)
Low body mass index (<18 kg/m2 )
Primary hypogonadism
Other disorders associated with
osteoporosis
2-99
Osteoporose fracturen en
BMD
50
40
Absolute Aantal
Fractuur incidentie
400
Vrouwen met fracturen
300
30
20
200
10
100
0
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
-3.5
0
E. Siris .
Surge on Ge neral’s Workshop on Oste oporosis and Bone Health, Decem ber 2002
Aantal fracturen
Fractures/1,000 persoonjaren
Incidentie
2-100
VFx & BMD bepalen samen het risicoprofiel
75x méér risico indien meerdere VFx en lage BMD
Ross 1991
Relatief Risico
75
Ann Intern Med;144 :919-23
25.1
14.9
10.2
7.4
4.4
1
Lage BMD Med BMD Hoge BMD
> 1 Fx
1 Fx
geen Fx
2-101
Wijziging van het
Osteoporose Paradigma
=
Wat we
(W)
niet meten ?
Bot
Densiteit
+
BMD = gr/cm2
Rel Risk
Fractuur
10
8
6
4
2
0
BMD (quartielen)
I
II III IV
2-102
10jaar - fractuurkans (%)
Leeftijd is de voornaamste risico factor
20
80
Leeftijd
Vrouwen
70
10
60
50
0
-3
-2
-1
T-score (SD)
0
1
2-103
Relatief risico (vs. BMI=25)
BMI en fractuurrisico
5
Alle fracturen
Osteoporose #
Heup fractuur
4
3
2
1
0
15
20
25
30
35
BMI ( kg/m2)
40
45
2-104
Risico voor heupfractuur (
man & vrouw )
Relatief Risico
3.0
2.0
1.0
0.0
Vroegere
fractuur
Fam.
(heup)
vrouw
man
Roken Steroiden Alcohol
ooit
> 2 /dag
Actueel
RA
2-105
Risk Factors for Osteoporotic
Fracture
With Relative Risk ≥ 2
(Major)
•
•
•
•
•
•
•
•
•
•
•
•
•
Age > 70 years
Menopause < 45 years
Hypogonadism
Fragility fracture
Hip fracture in 1o relatives
Glucocorticoids
Malabsorption
High bone turnover
Anorexia nervosa
BMI < 18 kg/m2
Immobilization
Chronic renal failure
Transplantation
With Relative Risk 1 - 2
(Moderate)
•
•
•
•
•
•
•
•
•
•
Estrogen deficiency
Calcium intake < 500 mg/d
Primary hyperparathyroidism
Rheumatoid arthritis
Bechterew Disease
Anticonvulsants
Hyperthyroidism
Diabetes mellitus
Smoking
Excessive alcohol
Adapted from Brown J. et al. CMAJ 2002; 167(10 suppl):S1-S34
2-106
Secondary Causes of Osteoporosis
Endocrinopathies
• Hypercalciuria with or
without renal stones
• Hypogonadism (incl.
hyperprolactinemia)
• Hyperparathyroidism
• Hyperthyroidism
• Cushing's syndrome
• Acromegaly?
Drugs
• Excess glucocorticoids
• Excess thyroid hormones
• Anticoagulants (heparin,
coumarins?)
• GnRH antagonists,
Aromatase inhibitoren
• Anticonvulsants
• Aluminum-containing
antacids
• Cyclosporine
• Rifampicin
• Exchange resins
? Methotrexate
? Loop diuretics
2-107
Risk Factors for Osteoporotic
Fracture
Non-modifiable:
•
•
•
•
•
•
•
Personal history of fracture
History of fracture in 1°relative
Caucasian race
Advanced age
Female
Dementia
Poor health/frailty
Potentially modifiable:
• Current cigarette smoking
• Low body weight (BMI < 18-20)
• Estrogen deficiency:
• Early menopause (< age 45 yr)
• Bilateral ovariectomy
• Premenopausal amenorrhea
• Low calcium intake (lifelong)
• Alcoholism
• Impaired eyesight
• Recurrent falls
• Inadequate physical activity
• Poor health/frailty
2-108
Specific Genetic Disorders
• Ehlers-Danlos syndrome
• Marfan's syndrome
• Homocystinuria
• Osteogenesis imperfecta
2-109
www.shef.ac.uk/FRAX
2-110
10 jaar
fractuurisico
www.shef.ac.uk/FRAX
2-111
Drempel voor BMD meting / Interventie
in Verenigd Koninkrijk
Kanis JA et al
Osteoporos Int 2008, 19:1395-408
2-112
Kost-effectiviteit
Totale kost
Nieuw
ke ”
j
i
el pay
p
p to
a
h
sc ess
t
aa ngn +/M lli
i
w
“
Nieuw
Actuele
Zorg
-
+
+ Nieuw
+
Nieuw
Gezondheidseffect (QALY)
QALY = Quality Adjusted Life Years
2-113
Osteoporose
• Veel voorkomend
• Fractuur wervel-heup
– Recidief fractuur
– Kwaliteit van leven, mortaliteit
• Diagnose
– RX opname : protocol
– BDM- DEXA
– FRAX: risico factoren
• Pathogenese
• Behandeling