Dr.Juan A.VenterDept. Clinical Imaging Sciences

Bloemfontein Academic Hospitals18/05/2012

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.

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.

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

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

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

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

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

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

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

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

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

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.

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 .

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

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

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

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.

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