internal medicine weekly conference 1392 internal medicine weekly conference 1392 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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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

0.4

0.5

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0.7

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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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0.7

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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



internal medicine weekly conference 1392 internal medicine weekly conference 1392 alimohammad fatemi...

Documents

nat rev endocrinol

photon energies

tissue types bone

common metabolic bone

diagnostic criteria

mortality asymptomatic

high morbidity

vertebral fracture