Internal Medicine Weekly Conference 1392 Internal Medicine Weekly Conference 1392 Alimohammad Fatemi Assistant Professor of Rheumatology Alimohammad Fatemi

Internal MedicineWeekly Conference

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BONE MINERAL DENSITY

Alimohammad Fatemi

Assistant Professor of Rheumatology

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1392Why Diagnosis Is Important?




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• The most common metabolic bone disease− 1/3 of women > 50− 1/5 of men > 50

• High Morbidity and Mortality

• Asymptomatic− 30-50% of vertebral fracture

Why Diagnosis Is Important?




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1392OSTEOPOROSIS

• A skeletal Disorder:

– Compromised Bone Strength

– Increased Risk of Fracture

Adams, Nat Rev Endocrinol. 2013




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1392BONE STRENGTH

Bone Mineral Bone Quality Bone Material





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1392BONE STRENGTH

Bone MineralDXA

Quantitative CT

Bone Material


Bone Quality




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1392BONE STRENGTH

Bone MineralDXA

Quantitative CT

Bone QualityDXA

Quantitative CTBone Turnover Markers

High Resolution CT/MRI

Bone Material





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1392BONE STRENGTH

Bone MineralDXA

Quantitative CT

Bone QualityDXA

Quantitative CTBone Turnover Markers

High Resolution CT/MRI

Bone MaterialNano Imaging





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1392Dual Energy X-ray Absorptiometry

(Gold Standard)




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1392Dual Energy X-ray Absorptiometry

(Gold Standard)

• Epidemiologic Studies

• Pharmacological Studies

• Reproducibility

• Safety− Low Radiation : 1/10 of Chest x-ray

• Diagnostic Criteria




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1392DEXA MACHINE

• X-ray Source (Tube)

• X-ray Collimators

• X-ray Detectors




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1392DXA MACHINE

X-ray Source

Patient




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1392DXA MACHINE

X-ray Source

(2 photon energies with different attenuation profiles)

Photons

Patient




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1392DXA MACHINE

X-ray Source


Photons

Patient

Collimator




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1392DXA MACHINE

X-ray Source


Photons

Patient

Collimator

Detector (detects 2 tissue types - bone and soft tissue)




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1392DEXA MACHINE




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1392DIFFERENT MACHINE

• MACHINES

– Hologic

– Lunar

– Norland

–MedLink




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1392Which Bones?

• Spine

• Femur

• Forearm




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1392SPINE




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1392FEMUR




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1392FOREARM




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1392What DXA Really Measures?




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• BMD




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• BMD

Bone Mineral Content (g) /Area (cm )2




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1392SPINE




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• BMD g/cm²

• %




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1392BMD

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

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1

10 15 20 25 30 35 40 45 50 55 60 65 70 75

Patient’s BMD




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1392BMD

0

0.1

0.2

0.3

0.4

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0.8

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10 15 20 25 30 35 40 45 50 55 60 65 70 75

PBM(Peak Bone Mass)

Patient’s BMD




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1392BMD

0

0.1

0.2

0.3

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0.5

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10 15 20 25 30 35 40 45 50 55 60 65 70 75

PBM(Peak Bone Mass)

Patient’s BMD

The reference standard is calculated is the female, white, age 20-29 years, NHANES III

database




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1392Comparison to Young Adult

BMD × 100

PBM




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1392SPINE




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• BMD g/cm²

• %

• T-Score




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1392T-SCORE

(Patient’s BMD) – (Young-Adult Mean BMD) 1 SD of Young-Adult Mean BMD




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1392T-SCORE

(Patient’s BMD) – (Young-Adult Mean BMD) 1 SD of Young-Adult Mean BMD

T-score =0.7 g/cm2 - 1.0 g/cm2

0.1 g/cm2

- 3.0 =




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1392SPINE




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• BMD g/cm²

• %

• T-Score

• Z-Score




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1392BMD

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0.1

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10 15 20 25 30 35 40 45 50 55 60 65 70 75

Patient’s BMD

Age-Matched BMD




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1392Comparison to Same Age/Sex(Z-SCORE)

Patient’s BMD – Age-Matched Mean BMD

1 SD of Age-Matched Mean BMD




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1392SPINE




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1392DEFINITIONS

• Normal Bone− -1 ≤ T-Score < +1

• Osteopenia− -2.4 < T-Score < -1

• Osteoporosis− T-Score ≤ -2.5




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1392When We Should Use Z-Score?




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• 0

• 0.1

• 0.2

• 0.3

• 0.4

• 0.5

• 0.6

• 0.7

• 0.8

• 0.9

• 1

• 10• 15• 20• 25• 30• 35• 40• 45• 50• 55• 60• 65• 70• 75

PBM(Peak Bone Mass)

Patient’s BMD

Age-Matched BMD




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• In children − Z < -2 Low BMD for chronological age




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• In children − Z < -2 Low BMD for chronological age

• Secondary osteoporosis




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• 0

• 0.1

• 0.2

• 0.3

• 0.4

• 0.5

• 0.6

• 0.7

• 0.8

• 0.9

• 1

• 10• 15• 20• 25• 30• 35• 40• 45• 50• 55• 60• 65• 70• 75

PBM(Peak Bone Mass)

Patient’s BMD

Age-Matched BMD




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1392Using T-scores vs. Z-scores




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• T-scores –WHO diagnostic

Postmenopausal women and Men ≥ 50

– Not for:

Healthy premenopausal women Men <50 Children




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• T-scores –WHO diagnostic

Postmenopausal women and Men ≥ 50

– Not for:


• Z-scores – Used for:





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1392Which Skeletal Sites Should Be Measured?




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Which Skeletal Sites Should Be Measured?

Every Patient• Spine– L1-L4



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• Hip– Total Hip– Femoral Neck



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1392What Is Ward’s Area?




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• A small calculated area – the mid portion of the femoral neck – BMD is the lowest




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• Overestimate the prevalence of osteoporosis




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• Overestimate the prevalence of osteoporosis

• Not part of WHO Criteria




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• Hip– Total Hip– Femoral Neck

Some Patients• Forearm– If hip or spine cannot

be measured– Hyperparathyroidism– Very obese



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33% radius




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1/3 radius




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1392DIAGNOSTIC PITFALLS




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• Patient’s demographic data

• Patient’s positioning

• Scan analysis

• Artifact

• Calibration




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• Scan analysis

• Artifact

• Calibration




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• Scan analysis

• Artifact

• Calibration




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1392SPINE




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1392SPINERegion of Interest




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SPINE




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SPINE




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1392SPINE




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1392HIP




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1392HIP

Region of Interest




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1392HIP




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1392HIP




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1392HIP




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• Scan analysis

• Artifact

• Calibration




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1392ARTIFACT




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1392ARTIFACT




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1392ARTIFACT




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• Scan analysis

• Artifact

• Calibration




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1392Calibration

Phantom




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MONITORING




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1392MONITORING

– Lumbar Spine 2.8%

– Femoral Neck 5.6%




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1392MONITORING

– Lumbar Spine 2.8%

– Femoral Neck 5.6%

(change in BMD ÷ prior BMD ) x100=significant percentage change




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1392INDICATIONS




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1392INDICATIONS• Women ≥ 65

• Younger Women with ≥ 1 risk factors

• Postmenopausal women with fracture

• Estrogen Deficiency

• Long-Term steroid

• Monitoring of Therapy




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THANKS FOR

YOUR ATTENTION



Documents

Internal Medicine Weekly Conference 1392 Internal Medicine Weekly Conference 1392 Alimohammad Fatemi Assistant Professor of Rheumatology Alimohammad Fatemi