IWO Meeting 1 November 2023 - Pitfalls DXA en VFA door Prof. dr. R. Slart (Groningen)

IWO Meeting 1 November 2023 - Pitfalls DXA en VFA door Prof. dr. R. Slart (Groningen)

1. 5 -11 -2023
De waarde en beperkingen van
botdichtheidmeting DXA/VFA
Riemer Slart MD, PhD
Nucleair geneeskundige, UMCG
Disclosures speaker
· None for this topic
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Structure of the presentation
· Introduction bone density (short)
Cortical bone
· The DXA – scanner
· Applicants
Trabecular bone
· DXA/VFA: scoring, reporting, pitfalls
─ ‘the images behind the report’
─ Examples (++pitfalls)
─ Other applications of DXA/VFA
· Take home messages
INTRODUCTION BONE DENSITY
Department of Nuclear Medicine and Molecular Imaging
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Osteoporosis
Normal
· Low bone mass (DXA: BMD)
Osteoporosis
Risk factors osteoporosis
· Fracture ≥ 50 yrs & recent fracture
· Persons long - term treatment with GC
· Persons ≥ 60 years with RF, without a recent fracture and no
GC
─ Low body weight , alcohol, smoking, falling , ..
─ Score RF ≥ 4
· Microarchitecture deterioration of bone
· Increased bone fragility and risk on bone #
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Prof. dr. 

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THE DXA - SCANNER
Department of Nuclear Medicine and Molecular Imaging
Principles of D(E)XA: UMCG Hologic Discovery
· Dual-energy X -ray Absorptiometry (DXA)
─ 40 KeV, 78 KeV
─ 2D image
─ Bone mineral density = BMC/W (g/cm 2)
· Bone mineral content = g/cm
· W = width of the scanned line (cm)
· Sites of measurement:
─ Lumbar spine
─ Hip
─ Wrist
· Duration of examination:
─ Around 10 minutes
· Radation dose:
─ < 0.01 mSv
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Quality control
· Quality control is essential
─ Daily phantom measurements
· What to look for?
─ Day tot day variance
─ Trend analysis
· Variants less ~1%
Current QA phantom
Lumbar spine DXA Hip DXA
See also the online International Society for Clinical Densitometry
(ISCD) 2019 document and the updated version of 2023
Courtesy of T. van den Wyngaert
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APPLICANTS
Department of Nuclear Medicine and Molecular Imaging
Applicants DXA’s
· Total DXA’s / yr UMCG: ± 5000 ( ± 2000 patients )
· Fracture out-patient-clinic ( traumatology )
· Internal medicine ( endocrinology / rheumatology )
· Gynaecology
· Pediatrics
· Others
─ GP
─ Organ transplantation (anti -rejection medication)
─ Oncology
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3. 5 -11 -2023
ASSESSMENT AND INTERPRETATION
CAPABILITIES OF DXA
Department of Nuclear Medicine and Molecular Imaging
· Assessment of the quality of the images
─ Quality
─ ‘Reconstruction’
· Correct positioning of the
patient
· Correct positioning of reference
lines
· Correct normal reference values
used
· Reporting:
─ Specific findings:
· Degeneration
· Fractures
· Calcifications of the aorta
· Rare findings (e.g. metal, X- ray contrast)
· Report Z- score and T - score
· VFA/IVA (Vertebral fracture assessment)
· Trabecular bone score (TBS)
· Conclusion
➢ WHO- classification: use lowest for diagnosis
(hip/spine)
→ does not apply to patients < 18 years of age
➢ Recommendation
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Components of DXA report (ISCD)
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T – score and Z – score
· T - score: compared with a young adult (29 yrs )
─ Fracture risk vs. young
─ 2 SD < mean: increased # risk
─ Used for WHO scoring
T – score and Z – score
WHO Classification
Normal
T- score
≥ - 1.0
· Z - score: compared with same age,
gender & race
─ Fracture risk vs. comparable subject
Low bone mass ( osteopenia )
Osteoporosis (severe)
< - 1.0 to > - 2.5
≤ - 2.5 (+ recent fracture )
─ NHANES III database BMD interpretation using T-score vs. Z-score*
(The National Health and Nutrition
Examination Survey)
T-score
In post/perimenopausal women and men age 50
years and older
Z -score
In healthy premenopausal women, men under
age of 50 years, and children**
Cannot be applied to healthy premenopausal
women, men under age 50, and children
Z -score -2.0 or less is defined as “below the
expected range for age”
Z -score above -2.0 is “within the expected
range for age”
WHO definition of osteoporosis. * ISCD (International Society for Clinical Densitometry) Official Positions
** **Beside BMD also other criteria should be included.
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Wrist DXA
· Non -dominant forearm
· Hyperparathyroidism
· No option for lumbar /hip DXA
· Extreme obesitas
CAPABILITIES OF DXA - BMD
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Wrist DXA Motion
GE Lunar
Hologic
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5. 5 -11 -2023
ROI Lumbar spine DXA
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Artefact VP drains: hydrocephaly
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Corrrect lumbar spine vertebrae: f.u .
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Z-score and database: ethnicity W/B
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Proximal femur DXA Hip position
· Use total hip or neck for diagnosis
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Lesser trochanter
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Benign bone tumour IgG4 and prednison therapy
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Femur head (2x) necrosis
Children
· Not WHO criteria
· Only Z - score
· No osteoporosis / osteopenia in the conclusion
· Specific database
X-pelvic MRI (T2)
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DXA: take into account:
· Variability between different vendors of scanner systems
· No repeating DXA < 1 year ( variation + 1%)
─ UMCG test-retest trial (EANM 2023 presentation)
· NHANES III (USA)
· Artifacts !
· Bone volume assessment challenging:
─ Overestimation BDM in larger subjects
─ Underestimation BDM in smaller subjects ( children)
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CAPABILITIES OF DXA - VFA
Fractures caused by osteoporosis
1. Low bone density
2. Disrupted microstructure
3. Fractures!
· Incidence vertebral fractures
─ 0.7% in all women > 50 yr
─ 0.2% in all men > 50 yr
· 38.000 - 60.000 QUALYs are lost
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Vertebral fractures
· N = 2500
· 2 out of 3 patients with a vertebral fracture have no complaints
· A fracture is a strong risk factor of more fractures
Jager et al, Osteoporos Int.2011 Apr;22(4):1059 -68.
VFA and reconstruction
VFA = vertebral fracture assessment
· Discovery A performed VFA lateral position ( patient supine)
─ No parallax and obliquity errors
─ Reproducible, easy and comfortable patient positioning
─ Simple and user friendly operating
· Computer
· Simple Point and click Genant criteria
· Quantitative
· Manual
· Correction
< 25% hoogte afname
25- 40%
>40% hoogte afname.
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Validation VFA DXA in UMCG
· 250 patients, retrospective study
· VFA & conventional X - ray thoracic and lumbar spine
· Quantitative comparison (6 - point method)
· Genant classification: grade & deformity
· Result: Kappa = 0.87
Hospers et al, Radiology , 2009
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Components of VFA report (ISCD) Example VFA
· Patient with Cushing’s disease
· BMD T -scores
─ Lumbar -0.6
─ Hip -0.1
· VFA :
─ mild fracture L1
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Example VFA: challenging Example VFA: artifact
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Example VFA: artifact
CAPABILITIES OF DXA - WBC
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Whole body composition: bone, lean mass, fat % Whole body composition
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Abdominal fat - InnerCore
· Visceral Adipose Tissue (VAT) calculated from WB
─ No extra acquisition and analysis time
─ No additional dose
─ Easier access than CT
─ Equivalent to CT measurement
· VAT is a strong parameter in
Cardiometabolic risk evaluation
─ normal < 100 cm²
─ 100 < increased < 160 cm²
─ high > 160 cm²
CAPABILITIES OF DXA
ABDOMINAL AORTA CALCIFICATION (AAC)
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AAC on DXA
·L1
· L1
·L2
· L2
·L3
· L3
·L4
· L4
DXA X-LWK
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Advanced DXA Using TBS (>40 yrs)
Kaplan-Meier curve for cumulative event -free survival in each group and population at risk at each time point.
Golestani et al., Ann Med 2010
The Trabecular Bone Sore (TBS) report is generated simultaneously with the standard DXA spine printout.
The report calculates an overall TBS, displays a texture image of the spine,
and provides age-matched reference values.
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12. 5 -11 -2023
Complete femur imaging
DXA – NEW FEATURES
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Solution – 3D -Shaper®: Advanced 3D Analysis
A software solution for the 3D visualization and analysis of the cortical
trabecular bone from 2D DXA scans using 3D-DXA technology.
Creating 3D model
and
3D -Shaper® Clinical Practice Integration
Auto detection of all
new DXA scans
PACS
Confidential © 3D- Shaper Medical 2023 Confidential © 3D- Shaper Medical 2023
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International Working Group on DXA Bone Mineral
Density Practice and Reporting Recommendations
A partnership between the European Association of Nuclear Medicine
(EANM), Canadian Association of Nuclear Medicine (CANM), International
Osteoporosis Foundation (IOF), European Society for Clinical and Economic
Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases
(ESCEO) International Society for Clinical Densitometry (ISCD), American
Society for Bone and Mineral Research (ASBMR) and European Calcified
Tissue Society (ECTS)
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13. 5 -11 -2023
TAKE HOME MESSAGES
Department of Nuclear Medicine and Molecular Imaging
Take home messages
· DXA imaging is reliable, patient friendly, easy method with a low radiation burden to quantify bone
density
· Beware of : variability (vendors , precision ), accurate ROIs needed , under/ overestimation BDM, small
vertebrae # or variants , artifacts , databases (NHANES III),….
· Clear indications: Osteoporose en fractuurpreventie 2022 FMS
· Updated Practice Guideline of Dual - energy X- ray Absorptiometry (DXA) appears soon
· DXA imaging is more than bone density measurement alone.
─ VFA is of additional value and needs attention
(Already included as a standard exam in the NL for Osteoporosis assessment)
─ TBS
─ Assessment of AAC with the aid of VFA has a prognostic value in terms of cardiovascular risk assessment
─ WBC
· DXA developments: in software & quantification: AFF, 3D femur head/neck
· Train (repeat it !) your (new) technologists
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Vragen? GC en DXA
[email protected]
Department of Nuclear Medicine and Molecular Imaging
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