1. What’s Wrong with this BMD Picture?
“Image Not For Diagnosis”: Not a license to not look at the images
Steven Burrell
Division of Nuclear Medicine

2. Introduction
Bone Mineral Density (BMD) plays an important role in fracture risk assessment and fracture prevention
BMD quantitatively measures absorption of photons by bone:
a measure of bone density and bone strength
Images are also generated
not the primary output of the test (unlike most Radiology)
Yet the images may contain important information
effecting the assessment of bone density and/or fracture risk
and sometimes other medical conditions, which may not be known
“Image Not for Diagnosis” is not a license to not review the images

3. This Presentation 12 cases
Identify what’s wrong with the images in each case, and how this may effect your assessment of BMD, fracture risk, or the patient’s overall medical care
Both hip and spine images are presented
abnormality may be on 1 image, or both
Some are obvious, some are subtle
how will you score?

4. Case 1 Very high density of the bones in the left hip, L1, and L4
After reviewing the case, click to advance to the discussion.
Very high density of the bones in the left hip, L1, and L4
(on images, but see also T-scores)
You check PACS for an explanation:

5. Right femoral neck not involved:
Diagnosis?
Paget’s Disease
Right femoral neck not involved:
Patient brought back to perform BMD on right
Fracture Risk?
- Low risk for fracture from osteoporosis…
May be at some increased risk due to the Paget’s:
not quantified
Bone Scan

6. Case 2
After reviewing the case, click to advance to the discussion.
Very high density of the bones in the spine and pelvis, not femur
(on images, but see also T-scores in spine)
You check PACS for an explanation:

7. Diagnosis?
Renal Osteodystrophy
Fracture Risk?
- Low risk for fracture from osteoporosis…
However, may be at increased risk due to the renal osteodystrophy: not quantified
Teaching Points
As with the Paget’s case earlier:
Medical conditions (which may be previously unknown!) may contribute to abnormal BMD
The fracture risk determined through osteoporosis algorithms may not apply
particularly true for multiple myeloma: many get BMD which may yield a low risk for fragility fractures, but they are at high risk for pathologic fractures, especially in the spine

8. Case 3 L4 appears short and wide: you wonder about a fracture
After reviewing the case, click to advance to the discussion.
L4 appears short and wide:
you wonder about a fracture

9. No known fracture on requisition or questionnaire
BMD Requisition
BMD Patient Questionnaire
No known fracture on requisition or questionnaire
L4 appears short and wide:
you wonder about a fracture

10. Teaching Point
A main goal of BMD testing is to assign a fracture risk
This patient was moderate risk by BMD and the provided information
By evaluating the images, you discovered a spine fragility fracture which elevates the patient to the high fracture risk category
 pharmacotherapy indicated
You recommend a new radiograph:
As suspected:
- new fracture of L4
You check PACS:
- no fracture
6 months earlier

11. Case 4 Odd configuration of femoral head and neck
After reviewing the case, click to advance to the discussion.
Odd configuration of femoral head and neck

12. - appears very different
You check prior BMD
5 years earlier
Current
- appears very different
Technologist’s note:

13. You check PACS:
- 3 months earlier: no fracture
You suspect a hip fracture from BMD image and recommend new hip radiographs:
- New fractures of femoral head & acetabulum
- Fragility fracture of hip:
 high risk for future fractures
- Needs management for osteoporosis AND immediately for previously unknown fractures
Teaching Points
While unknown spine fractures are occasionally found, as in prior case, finding an unknown hip fracture is rare… +++ important to the patient

14. Case 5 2 Relevant Findings: do you see them both? Finding 1:
After reviewing the case, click to advance to the discussion.
2 Relevant Findings: do you see them both?
Finding 1:
Bilateral ureteric stents project over L4 (that counts as 1 finding)
L4 should be excluded from analysis (admittedly the overlap is minimal)
Finding 2:
Unusually high bone density diffusely (images, T-scores)
so you check PACS…

15. diffuse increased uptake in bones
Bone Scan Findings?
diffuse increased uptake in bones
low activity in kidneys & soft tissues:
 “Super Scan” CT
CT Findings?
diffuse sclerosis throughout
Diagnosis?
metastatic prostate cancer
(with bilateral ureteric obstruction)
Discussion
bone metastases are not uncommon in age range getting BMD testing
may not be known: BMD may be first test to discover this
confirm with radiographs
Bone Scan

16. Case 6 Densities in RLQ, including over L4
After reviewing the case, click to advance to the discussion.
Densities in RLQ, including over L4

17. Teaching Points
Needless to say, metal projecting over bone will artifactually increase BMD
Technologist should exclude the lumbar level from analysis
Responsibility for the case is ultimately with the radiologist
Surgical clips
Densities in RLQ, including over L4

18. Case 7 Densities in RLQ, including over L2 and L3
After reviewing the case, click to advance to the discussion.
Densities in RLQ, including over L2 and L3

19. Teaching Points
As per prior case:
metal increases perceived BMD
levels need to be excluded
Densities in RLQ, including over L2 and L3
IVC filter overlies vertebral bodies

20. A companion case: No subtleties here!
LVAD (Left Ventricular Assist Device) and leads overlie upper L-spine

21. Case 8
After reviewing the case, click to advance to the discussion.
Midline gap at L3 + L4
(+ L5, not included in BMD)

22. Midline gap at L3 + L4
(+ L5, not included in BMD)
Laminectomies

23. excision of posterior elements decreases measured BMD:
Teaching Points
DXA machines measure an “areal BMD” (g/cm2) based on a 2-D image, not a true volumetric density (g/cm3)
this is the density of all bone in the projected area, not just the vertebral body
excision of posterior elements decreases measured BMD:
lowering the T-score when compared to normal database
though true BMD in vertebral body is unchanged
these levels should be excluded from the analysis
Midline gap at L3 + L4
(+ L5, not included in BMD)

24. Case 9 Gross abnormalities at hip rotated extra density
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Gross abnormalities at hip
rotated
extra density

25. Gross abnormalities at hip rotated extra density
++ heterotopic bone in paraplegic patient
(spinal cord injury)

26. Paraplegic patients lose bone mass and are at risk for fractures:
Teaching Points
Paraplegic patients lose bone mass and are at risk for fractures:
often undergo BMD testing
Assessment of hips can be difficult:
difficulty achieving standard positioning
heterotopic bone
Ultimately hips may not be assessable
++ heterotopic bone in paraplegic patient
(spinal cord injury)

27. Case 10 images are “noisy”
After reviewing the case, click to advance to the discussion.
images are “noisy”
especially in spine, pelvis, & femoral neck, but not more distal femur
with curvilinear transition zone

28. images are “noisy”
especially in spine, pelvis, & femoral neck, but not more distal femur
with curvilinear transition zone
Large pannus overlies femoral neck

29. DXA = Dual Energy Absorptiometry
Teaching Points
DXA = Dual Energy Absorptiometry
purpose of the 2 energies is to discriminate attenuation by bone from that from soft tissue
and thus calculate bone density
however, the approach is not perfect, and large amounts of overlying soft tissue can lead to inaccurate results
patients should (diplomatically) be asked to lift their pannus upward
For the same reason, when patients gain or lose a lot of weight (eg 10%1), comparison of measured BMD to prior may not be valid
Large pannus overlies femoral neck
(This was a subtle case, but common)
1. Siminoski K et al. Canadian Association of Radiologists Technical Standards for Bone Mineral Density Reporting. CARJ 2013;64:

30. Case 11 Rounded densities project over and beside L2
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Rounded densities project over and beside L2

31. Same patient, 2 prior BMD studies
Teaching Point
As with the previous cases of overlying metal, affected levels should be excluded from the analysis
- variable locations: pills
- these pills are dense (? calcium)

32. Case 12 Density traversing upper abdomen, projecting over L1 + L2
After reviewing the case, click to advance to the discussion.
Density traversing upper abdomen, projecting over L1 + L2

33. CT with oral contrast the same day

34. Teaching Points
BMD should be deferred when there has been recent:
oral contrast
increases measured density
Nuclear Medicine study
emitted photons can be detected by DXA machine
In this case the study went ahead:
- L1 + L2 should be excluded

35. Summary
Although primary output of a BMD study is numeric, images are generated
The images need to be reviewed:
should be second nature for Radiologists
You may discover:
Artifacts:
leading to erroneous: BMD values  fracture risk category  management
Important medical conditions:
you may be the first to diagnose!