Transcript 1.Radiologic Approach to Osteoporosis and Osteomalacia2

Dr.Juan A.Venter
Dept. Clinical Imaging Sciences
Bloemfontein Academic Hospitals
18/05/2012
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Most common of all metabolic bone disorders
Significant morbidity(50% for hip fractures)
and mortality(20% for hip fractures in 1 year)
Treatment cost in Europe : 75 billion Euros by
2050.
Lifetime Osteoporotic Fracture Risk(Caucasian)
Woman- 40%
Men - 20%
Preventive therapies available.
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Systemic skeletal disease characterized by low
bone mass and microarchitectural deterioration
of bone tissue with a consequent increase in
bone fragility and susceptibility to fracture
which usually involves the wrist ,spine, hip,
pelvis,ribs or humerus.
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Detect osteoporosis - (Fragility) fractures
Quantification -Measure bone mass :
Semiquantitative(Conventional Radiography)
Quantitative (Bone Mass Densitometry)
Morphometry :
Radiogrammetry
Singh Index
Vertebral Morphometry
Bone Mineral Densitometry(BMD) :
DXA (Dual energy X – ray absorptiometry) - Axial/Peripheral
QCT (Quantitative CT – Axial/Peripheral),HRCT
Other – QUS,QMR
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Increased Radiolucency/Cortical Thinning
Notoriously inaccurate : 30 – 40 % loss of bone
mass need to be present before detection
25 % of apparent osteopenia on radiography
(technical faults) or vertebral fractures(juvenile
epiphysitis,normal variants,trauma) have normal
BMD
Can detect osteomalacia/hyperparathyroidism
Loss of at least 20% or 4 mm vertebral body height
required for diagnosis of vertebral fracture –
increase risk of subsequent fractures of vertebrae x
2 and hip x 5
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Not pain free within 6-8 weeks
Non Anterior Wedge
Posterior Wedge(other than L4+5)
Above T7
Concave posterior vertebral border is more likely a sign of benign
osteoporotic fracture, whereas a convex posterior border suggests
malignant disease.
Consider :
Neoplastic disease – multiple myeloma/metastases
Osteomalacia
Schauermans disease(Juvenile epiphysistis)
Trauma
Degeneration
MR imaging findings of malignant disease include multiple contrast
enhancing lesions or soft-tissue masses, with or without encasing
epidural masses and destructive changes
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Rapid scanning
Precise results if performed meticulously
Extreme low doses of radiation
Vertebral assessement from lateral images
obtained on fan beam DXA system can be done
at 1/100 th of dose of conventional
radiography.
Central/Peripheral DXA
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Calibrated at least 1/week
Meassurement monoplanar – g/cm2 and therefor
size dependant (children)
All calcium in path of electron beam contributes to
BMD(Aortic calcifications
degenerative/hyperostotic changes/vertebral
wedging,metallic pinning) with overestimation of
BMD.Exclude these areas from analysis/Lateral
scanning
Strontium ranelate treatment – artefactual increase
in BMD
Results of different scanners not interchangeable
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Need appropriate race and sex matched BMD
reference ranges – ethnic differences in BMD and
fracture prevelance
Expressed as standard deviation from :
Age matched – Z Score
Peak bone mass – T Score
Normal - > – 1 sd
Osteopenia - < -1 > – 2.5 sd
Osteoporosis - < -2.5 sd
Severe Osteoporosis - < -2.5 sd + 1or > fragility
fractures
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Woman > 65 years and men > 70 years
Radiographic evidence of osteoporotic
vertebral fractures or apparent osteopenia
History of fragility fractures after age 40
Known causes of secondary osteoporosis :
Early menopause(< 45 years of age) / hypo
gonadism in men/woman
Systemic diseases with adverse effect on bone
Bone toxic drugs
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Facilitate desicions regarding initiation/
discontinuation of drug therapy
(biphosphonates /HRT)
Strong clinical risk factors:
Family history of hip fractures or osteoporosis
BMI < 19 kg/m2
Regular C2H5OH intake(>3 drinks/day)
Smoking
Poor nutrition /Calcium intake/Vitamin D
exposure
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Low specificity – < 50 % of known osteoporotic
fractures have BMD in osteoporotic range(T < 2.5)
Other risk factors like propensity to falls or
qualitative risk factors like bone turnover not
included
Extrapolation to other populations measured at
different skeletal sites with other techniques
(QUS,QCT) not acceptable.
Other metabolic bone diseases
Intervention threshold applicable to all
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Confirm diagnosis with BMD or presence of fragility fracture
before initiation of treatment with bone active drugs.
Axial BMD to be used to diagnose and access rate of bone
loss/gain. QCT/QUS not recommended and results cannot be
applied to T score based WHO diagnostic classification
Lowest BMD value measured at spine,total femur and femur
neck(or distal radius if invalid)
Express results for post menopausal Caucasian woman as T
scores and Z scores for pre menopausal woman and men < 50
year
Men over 50 years : Employ female reference data to determine
T score
Local black population : use reference data for Caucasian
females for all subjects of all races until local reference values
become available.
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Children:Low BMD + significant fracture
history
Follow up scans every 18-24 months or earlier
in GIOP
Search for evidence of vertebral compression
fractures in all who qualify for BMD
measurement – Standard x-ray and use
modified Genant semiquintative system to
grade (Gr.1-3) Higher grade = higher risk for
subsequent fractures of hip and vertebrae or
DXA VFA .
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Considered treatment after prior fragility
fracture(wrist, spine,hip ,pelvis ,rib ,humerus)
regardles of BMD value
Considered treatment if DXA T Score < -2.5 at hip
or spine
Considered treatment if DXA T score -1- -2.5
(osteopenia) if significant clinical risk factors.
BMD measured on all patients on long term
glucocorticosteroids(50% develop GIOP regardless
of dose)-start treatment if T Score < - 1.5
Biphophonates – 1st line preventative therapy and
anabolics reserved for advanced disease
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Reduce the high subjectivity and poor
reproducibility of qualitative readings
Vertebral fractures are one of the most important
CRF – 60% asymptomatic and go undetected if not
routinely searched for
Visualize lateral spine on DXA with VFA software
Lower radiation dose and cost compared to
conventional radiography
Conventional radiography remain gold standard –
often only requested if fracture is suspected
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Separate estimation of cortical and trabecular bone
True volumetric density – g/cm3 making it non size
dependant (children/small stature)
Performed with calibration reference phantom to
transform HU into BMD equivalents
Radiation dose compares favourably with conventional
radiography
Excellent for predicting vertebral fractures and serially
measuring bone loss - selectively assesses the
metabolically active and structurally trabecular bone
Increase in marrow fat is age related, single-energy CT
data can be corrected with use of age-related reference
databases
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Can be used to detect differences in trabecular
structure depending on patient age, BMD, and
osteoporotic status
Most often performed at peripheral sites such
as the calcaneus, knee, and wrist.
Substantial improvement in fracture
discrimination made possible by considering
structural information as well as BMD
May replace biopsy when this would be
advocated.
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http://www.iofbonehealth.org/ - accessed
28/04/2012
Grainger and Allison’s Diagnostic Radiology A
Textbook of Medical Imaging,5th Edition
Orthopedic Imaging A Practical Approach
Adam Greenspan,5th Edition
Radiographics : September – October 2011
Integrated Imaging Approach to Osteoporosis:
State-of-the-Art Review and Update