Skeletal Scintigraphy
BY
AHMED RAMADAN
ASSISTANT LECTURER
CLINICAL ONCOLOGY &NUCLEAR MEDICINE DEPARTMENT
MANSOURA UNIVERSITY
Bone Scan
 Introduction
– Definition
– Advantages vs
Disadvantages
 Anatomy
 Techniques
– Radiopharmaceutical
– Mechanism of uptake
– Imaging Technique
 Interpretation of bone scan
 Clinical applications
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.
Advantages VS Disadvantages
Advantages
 Whole-body evaluation
in one test/ same rad
exposure.
 Low radiation exposure
 Sensitive evaluation
Disadvantages
 Needs
radiopharmaceuticals
& gamma camera not
widely available
 Low specificity
 Cost is high.
Anatomy
Anatomy
 Axial skeleton [head
and trunk]
o Skull
o Thorax (ribs & sternum),
o Spines (includes sacrum &
coccyx)
 Appendicular skeleton
o Shoulder girdle: clavicle
& scapula
o Upper Extremity
o Pelvic girdle
o Lower Extremity
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
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
Pathophysiology
Tc-99m MDP uptake depends on osteoblastic
and osteoclastic activity.
Increased uptake
osteoblastic activity
Decreased uptake
osteoclast activity
pure lytic lesion
Pathophysiology
Possible Mechanism of Increased Uptake:
 Increased blood flow
 Increased osteoid formation
 Increased mineralization of osteoid
 Interrupted sympathetic nerve supply
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.
Poor Image Quality
 Renal impairment
 Decreased cardiac output
 Dehydration
 Extravasation of the radiopharamceutical
 Aging.
 Underdosage of the radiopharmacetical.
 Obesity.
Imaging Acquisition
Routine whole-body
bone scan
3-phase bone scan
imaging
SPECT & SPECT/CT
imaging
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)
3-phase bone scan imaging
 Phase 1; Vascular phase: 60 s
dynamic immediately post
injection
Vascular phase
 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
Soft-tissue
delayed 2-3hr
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
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
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.
Normal Pediatric Bone Scan
Normal pediatric bone
scan showing increased
tracer activity in the
epiphysis
(growth plates).
False negative bone scan
Multiple myeloma
Renal cell carcinoma
Thyroid carcinoma
Neuroblastoma
Highly aggressive anaplastic tumors
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.
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.
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.
Metabolic Superscan
Diffusely increased bone
activity (increased bone
vs soft tissue activity)
causes:
 Metabolic bone disease
hyperparathyroidism.
 Hematological diseases
 Renal osteodystrophy.
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
Osteosarcoma
Primary bone tumor
affecting right upper
tibia.
Degenerative Changes
 Joints: Arthritis
– Knees & Ankles
 Spine: Spondylosis &
Disc prolapse
–Dorsal Spine
–lumbar Spine
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.
Stress Fracture
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.
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
Hypertrophic Pulmonary Osteoarthropathy
Hypertrophic Pulmonary
Osteoarthropathy
(HPOA), from lung
cancer. Linear cortical
uptake can also be seen
with shin splints.
Paget’s Disease of The Bone
Paget’s disease
Involvement of L4 resembles the Mickey mouse sign.
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.
Osteomyelitis
Acute Osteomyelitis of the right calcaneus positive on all
three phases.
Three Phase Bone Scan In Infection
Disease
Cellulitis
Flow
(I)
Diffuse
increase
Pool
(II)
Diffuse
increase
Delayed
(III)
Normal
Acute Ostemyelitis Focal
without Cellulitis increase
Focal increase Focal
increase
Acute Ostemyelitis Diffuse
with Cellulitis
increase
Diffuse
increase
Focal
increase
Septic Arthritis
Diffuse
increase
Particular
increase
Diffuse
increase
THANK YOU