1. Skeletal ScintigraphyBy
Ahmed Ramadan
Assistant Lecturer
Clinical Oncology &Nuclear Medicine Department
Mansoura University

2. Bone Scan Introduction – Definition – Advantages vs Disadvantages
Anatomy
Techniques
– Radiopharmaceutical
– Mechanism of uptake
– Imaging Technique
Interpretation of bone scan
Clinical applications

3. Definition
A bone scan is a test that detects areas of increased or decreased bone activity by injecting a certain radiopharmaceutical i.e. Tc-99m MDP. This may indicate bone injury or disease.

4. Advantages VS Disadvantages
Needs radiopharmaceuticals & gamma camera not widely available
Low specificity
Cost is high.
Whole-body evaluation in one test/ same rad exposure.
Low radiation exposure
Sensitive evaluation

5. Anatomy

6. Anatomy Axial skeleton [head and trunk] Skull Thorax (ribs & sternum),
Spines (includes sacrum & coccyx)
Appendicular skeleton
Shoulder girdle: clavicle
& scapula
Upper Extremity
Pelvic girdle
Lower Extremity

7. Radiopharmaceuticals
Bone-seeking agents are analogs of calcium, phosphates.
The most widely used Radiopharmaceuticals is
Tc-99m labeled
diphosphonates
Tc-99m Methylene diphosphonate
(Tc-99m MDP)
Tc-99m MDP

8. Tc-99m MDP Used within 4 hrs after preparation.
Labelling yield: > 95%, avoid injecting air
into the vial »»» oxidation of Tc »»» oxidized
Tc »»» poor tagging of phosphates.
High target/bcg ratio within 2-3 hrs. with
50-60% of the injected activity localizing in
bone (max sk uptake at 5 hrs)
Rapid renal clearance
Renal Impairment: increased soft tissue activity, poor image quality, delayed excretion, higher radiation exposure due to retained high activity

9. Pathophysiology
Tc-99m MDP uptake depends on osteoblastic and osteoclastic activity. Increased uptake Decreased uptake osteoblastic activity osteoclast activity
pure lytic lesion

10. Pathophysiology Possible Mechanism of Increased Uptake:
Increased blood flow
Increased osteoid formation
Increased mineralization of osteoid
Interrupted sympathetic nerve supply

11. Technique Preparation: None Injection of Tc-99m 20-25
mCi IV, (250 uCi/Kg) for children, good hydration afterwards & frequent voiding
Wait for about 2-3 hrs to start imaging, avoid contamination
Empty bladder prior to scanning
Change the cloth and remove things likely cause artifact.

12. Poor Image Quality Renal impairment Decreased cardiac output
Dehydration
Extravasation of the radiopharamceutical
Aging.
Underdosage of the radiopharmacetical.
Obesity.

13. Imaging Acquisition Routine whole-body bone scan
3-phase bone scan imaging
SPECT & SPECT/CT imaging

14. Routine Bone Scan Imaging
Whole-body planar imaging in anterior and posterior projection
Additional static images if required eg. Oblique or additional spot views(squat view)

15. 3-phase bone scan imaging
Phase 1; Vascular phase: 60 s dynamic immediately post injection
Phase 2; Soft-tissue (blood-pool) phase: 5 min post injection.
Phase 3; Delayed (bone) phase: 2-3 hr post injection.
Indications:
• Infection: DDx acute
osteomyelitis vs cellulitis
• Avascular necrosis
• Tumors: primary
tumor
Vascular phase
delayed 2-3hr
Soft-tissue

16. Indications Neoplastic disease: Primary bone tumors & Bone metastasis
– Staging for malignancies that have high incidence of bone
metastasis eg. cancers of prostate, breast, lung,
neuroblastoma.
– Unexplained bone pain in a patient with known malignancy (neg X-ray)
– Unexplained bone pain in a patient with no history of
malignancy.
Trauma: Fracture/ Stress injuries (eg, stress fracture, shin splints).
Infection:(osteomyelitis)
Avascular necrosis
Arthritis:Degenerative changes
Metabolic & Endocrine disorders: (eg, Paget’s Disease, Hyperparathyroidism)
Bone marrow diseases: Sickle cell disease

17. Interpretation
Lytic lesions must cause at least 30%- 50% demineralization to be visible by radiography.
Bone scan is much more sensitive in detecting metastatic lesions in majority of cancers.
Results
Normal- symmetrical
Abnormal
• Increased uptake
• Decreased uptake
• Mixed

18. Normal Whole Body Bone Scan
The scan on the right shows normal distribution of the tracer, mild normal soft tissue activity, excretion from the kidneys into the bladder, scoliosis and mild associated degenerative changes in the lumbar spine.

19. Normal Pediatric Bone Scan
Normal pediatric bone scan showing increased tracer activity in the epiphysis (growth plates).

20. False negative bone scan
Multiple myeloma
Renal cell carcinoma
Thyroid carcinoma
Neuroblastoma
Highly aggressive anaplastic tumors

21. False positive bone scan
Contamination
Physiologic activity eg. urine along urinary tract.
In patients with known malignancy and no benign radiographic explanation for a bone scan lesion, additional workup is necessary.
False positive bone scan is also high when a single lesion is seen e.g:
• A single spinal lesion on bone scan has a 10%-20% chance of representing
a metastatic focus.
• A single rib lesion on bone scan has a 10% chance of representing a metastatic
focus. Lesions in consecutive ribs are almost always traumatic in origin.
Lesions in nonconsecutive ribs have a high chance of representing metastatic
disease.
• A single sternal lesion on bone scan in a patient with breast cancer, on the
other hand, has an 80% chance of representing a metastatic focus.
• In the case of prostate cancer, PSA level < 10 μg/L is a good predictor of
a negative bone scan.

22. Bone Metastases
Disseminated Bone Metastasis from breast cancer. Lesions in the vertebral bodies and the femur neck, which are at the risk for pathological fracture should be mentioned separately.

23. Metastatic Superscan
Diffuse metastatic disease, from prostate prostate*, breast, lung cancer. In a super scan from bone metastasis, there is intense diffuse uptake in the skeleton (in the distribution of active marrow) and minimal activity in the kidneys, bladder, and the soft tissues.

24. Metabolic Superscan
Diffusely increased bone activity (increased bone vs soft tissue activity)
causes:
Metabolic bone disease hyperparathyroidism.
Hematological diseases
Renal osteodystrophy.

25. Flare phenomenon
The bone scan appears worsening, or even shows new lesions, during the first several months following chemotherapy, orchiectomy and radiation therapy, while the patient's clinical condition improves
A repeat bone scan will show marked improvement after several months.
The flare phenomenon occurs in up to 20% of patients;
depending on tumor type, therapeutic regimen and the interval between therapy and the bone scan.
This phenomenon may persist upto 6 months

26. Primary bone tumor affecting right upper tibia.
Osteosarcoma
Primary bone tumor affecting right upper tibia.

27. Degenerative Changes Joints: Arthritis – Knees & Ankles
Spine: Spondylosis & Disc prolapse
–Dorsal Spine
–lumbar Spine

28. Delayed images from a bone scan showing fracture of the left 6th rib.
Traumatic Fracture
Whole body bone scan showing multiple occult bilateral rib fractures (arrowed). The linear alignment is typical of fractures.
Delayed images from a bone scan showing fracture of the left 6th rib.

29. Stress Fracture fractures will not be evident on initial
More than 80% of stress
fractures will not be
evident on initial
radiographs, while the
sensitivity of bone scan
approaches 100%
Delayed images from
the bone scan of a
runner showing stress
fracture at the right
distal tibial medial
cortex.

30. (cold) area surrounded by an area of increased activity
Avascular Necrosis
Diagram shows how a subcapital fracture of the femoral neck cuts off othe blood supply to the femoral head, resulting in osteonecrosis
Central Photopenic
(cold) area surrounded
by an area of increased activity

31. Hypertrophic Pulmonary Osteoarthropathy
Hypertrophic Pulmonary Osteoarthropathy (HPOA), from lung cancer. Linear cortical uptake can also be seen with shin splints.

32. Paget’s Disease of The Bone
Paget’s disease Involvement of L4 resembles the Mickey mouse sign.

33. Sickle Cell Disease
Bone marrow expansion from anemia (increased bone vs soft tissue activity), splenic uptake from repeated infarctions and calcifications. Increased uptake can be seen in the kidneys from iron overload, from multiple transfusions.

34. Osteomyelitis
Acute Osteomyelitis of the right calcaneus positive on all three phases.

35. Three Phase Bone Scan In Infection

36. Thank you