Bone scintigraphy uses radiolabeled phosphonates injected intravenously to evaluate bone formation. It produces whole body images of tracer distribution in the skeleton. Increased uptake indicates elevated osteoblastic activity such as might occur with fractures, tumors, or metastases. The scan has high sensitivity but low specificity for bone abnormalities, so findings must be interpreted in clinical context. It is useful for detecting skeletal involvement by cancer or other bone diseases.

1. Bone Scintigraphy

2. Bone Scanning
• Bone scintigraphy is a diagnostic
study used to evaluate the
distribution of active bone
formation in the body.
• Phosphate analogues can be
labeled with 99mTc and are used
for bone imaging because of their
good localization in the skeleton
and rapid clearance from soft

3. • It can be performed as:
– a) Limited bone scintigraphy or spot views
(planar images of a selected portion of the
skeleton)
– b) Whole-body bone scintigraphy (planar
images of the entire skeleton in anterior
and posterior views)
– c) SPECT (single photon emission
computed tomography- image of a portion
of the skeleton)
– d) Multiphase bone scintigraphy
(immediate and delayed images to study

4. • In oncology the standard technique of
bone scintigraphy is considered to be the
whole-body scan.
• Whole-body bone scintigraphy produces
planar images of the skeleton, including
anterior and posterior views of the axial
skeleton.
• Anterior and/ or posterior views of the
appendicular skeleton also are obtained.
• Additional views are obtained as needed.

5. • Limited bone scintigraphy or spot views
are indicated only where a specific
clinical problem detected on whole-body
imaging needs to be clarified.
• SPECT has a higher diagnostic specificity
than planar imaging and may be
preferable when there is diagnostic
uncertainty.
• Multiphase bone scintigraphy is more
useful when trauma or musculoskeletal
inflammation/infection is suspected and is
not usually indicated in oncology.

6. • Multiphase bone scintigraphy usually
includes blood flow images, immediate
images, and delayed images.
• The blood flow images are a dynamic
sequence of planar images of the area of
greatest interest obtained as the tracer is
injected.
• The immediate (blood pool or soft tissue
phase) images include 1 or more static
planar images of the areas of interest,
obtained immediately after the flow portion
of the study and completed within 10 min

7. • Delayed images may be limited to
the areas of interest or may include
the whole body, may be planar or
tomographic, and are usually
acquired 2–5 hrs after injection.
• If necessary, additional delayed
images may be obtained up to 24 h
after tracer injection.

8. Clinical indications
Oncological indications
• Primary tumours (e.g. Ewing’s sarcoma,
osteosarcoma)
• Staging, evaluation of response to therapy
and follow up of primary bone tumors
• Secondary tumours (metastases)
– Staging and follow-up of neoplastic diseases
– Distribution of osteoblastic activity prior to
radiometabolic therapy

9. Indications for non-neoplastic diseases:
• Bone scan changes occur whenever there is
an increase in blood flow to a lesion or there
is an alteration in osteoblastic activity. For
this reason, bone scan images also reveal
abnormalities in non-neoplastic diseases
such as:
– Stress and/or occult fractures.
– Trauma – accidental and nonaccidental.
– Musculoskeletal inflammation and infection
– Bone viability (grafts, infarcts, osteonecrosis).
– Metabolic bone disease.
– Arthritides

10. – Complications of hardware/prosthetic joint
replacement, loose or infected joint prosthesis
– Pain of suspected musculoskeletal etiology.
– Heterotopic ossification.
– Complex regional pain syndrome (CRPS)
– Spondylolysis
– Abnormal radiographic, lab or clinical findings.
– Distribution of osteoblastic activity prior to
radiopharmaceutical administration for
palliation of bone pain.
– Other bone disease, such as Paget disease,
Langerhans cell histiocytosis, or fibrous
dysplasia.

11. Contraindications
• Pt. recently had contrast media for
a different study.
• Pt. Recently (24-48 hrs) had a
TC99m-based nuclear scan

12. • patients should be well hydrated and
instructed to drink 2 or more glasses of
water between the time of injection and the
time of delayed imaging.
• The patient should be asked to urinate
immediately before delayed imaging and to
drink plenty of fluids for at least 24 h after
radiopharmaceutical administration.

13. • Technetium-99m medronate (methylene
diphosphonate [MDP]),
• technetium-99m oxidronate
(hydroxymethylene diphosphonate
[HMDP]),
• or hydroxyethylene diphosphonate (HDP)
is administered intravenously.

14. Precautions
• Pregnancy (suspected or confirmed). In the
case of a diagnostic procedure in a patient
who is known or suspected to be pregnant,
a clinical decision is necessary to weigh
the benefits against the possible harm of
carrying out any procedure.
• Breast-feeding should be discontinued and
milk expressed and discarded when
possible for 24 h (and atleast for 4 h) post
radiopharmaceutical administration).

15. Physiology
• Phosphonates concentrate in the mineral
phase of bone: nearly two-thirds in
hydroxyapatite crystals and one third in
calcium phosphate.
• Two major factors control accumulation of
phosphonates in bone, namely blood flow
and extraction efficiency, which in turn
depend on capillary permeability, acid-base
balance, parathyroid hormone levels, etc.
• About 50% of the activity injected

16. • Maximum bone accumulation is reached 1
h after injection and the level remains
practically constant up to 72 h.
• The blood clearance of these
radiopharmaceuticals is high. Three hours
after injection only 3% of the administered
activity remains in the bloodstream.
• The peak of activity through the kidneys is
reached after approximately 20 min. Within
1 h, with normal renal function, more than
30% of the unbound complex has
undergone glomerular filtration andwithin 6

17. • The quantity of phosphonates eliminated
via the intestines is insignificant.
• The biological half-life of phosphonates is
26 h.
• In a normal bone scan all but the smallest
bones are recognisable.
• On the anterior view it is possible to
distinguish the sternum.

18. • On the posterior view the bodies of
individual vertebrae are seen, as well as
pedicles and transverse and spinous
processes in the lower dorsal and
lumbar regions. In this projection the
sacro-iliac joints usually have the highest
uptake.
• In children the appearance of the bone
scan is characterised by areas of uptake
due to active growth in the epiphyseal
regions.
• After fusion of the epiphyses these areas
are no longer visible.

19. • When evaluating bone scan images, the
following points should be taken into
consideration:
– The bone scan is very sensitive for
localisation of skeletal metastases or tumours,
but the specificity is low. It must be interpreted
in the light of all available information,
especially patient history, physical
examination, other test results and previous
studies.
– Symmetry in the representation of right and
left sides of the skeleton and homogeneity of
tracer uptake within bone structures are
important normal features. Particular attention
should be paid to left–right asymmetries

20. Bone abnormalities
• Both increases and decreases in
tracer uptake have to be assessed;
abnormalities can be either focal or
diffuse.
• Increased (decreased) tracer
activity in the bone, compared with
that in normal bone, indicates
increased (decreased) osteoblastic
activity.

21. • Differential diagnosis can sometimes be
based on the configuration of the
abnormality or abnormalities and the
location and number of abnormalities.
Most patterns are non-specific.
• Focal decrease without adjacent increase
in tracer uptake is less common than
focally increased activity and is often
caused by benign conditions (attenuation,
artefact or absence of bone, e.g. due to
surgical resection).

22. • Decreases in the intensity of tracer
uptake and in the number of
abnormalities compared with a previous
study often indicate improvement or may
occur secondary to focal therapy (e.g.
radiation therapy).
• Increases in the intensity of tracer uptake
and in the number of abnormalities
compared with a previous study often
indicate progression of disease but may
reflect a flare response to therapy.

23. Soft tissue findings
• Normal structures should be noted: kidneys
and bladder. Tracer uptake in the kidney
can be focal or diffuse.
• Generalised increased soft tissue uptake
compared with normal bone can be due to
renal failure, dehydration or a shortened
interval between injection and imaging.
• A generalised decreased soft tissue uptake
compared with normal bone can be due to
“superscan” or a prolonged interval
between injection and imaging.

24. Normal Bone Scan
• tracer uptake greatest in axial
skeleton
• background activity of soft
tissue
• kidneys routinely visualized
• skull can appear uneven
(variations in calvarial
thickness)
• sites of persistently increased
symmetric uptake, are
acromial and coracoid
processes of the scapulae,
the medial ends of the
clavicles, the junction of the

25. Normal Bone Scan
• Hyperostosis Frontalis
• Dental Problems
Common Cold

26. Normal Bone Scan-Pediatrics
Growth Center
most intense: distal femur-proximal tibia-
proximal humerus (which is also the order of
relative occurence of osteosarcoma in children)
Costochondral junctions

27. Additional Views
Tail On Detector-TOD

28. SPECT

29. Metastatic Bone Disease
Prostate Cancer

30. • The presence of multiple, randomly
distributed areas of increased uptake of
varying size, shape, and intensity is highly
suggestive of bone metastases
• Though encountered in other pathologic
conditions, it is often possible to distinguish
metastatic disease from other entities by
analyzing the pattern of distribution of the
abnormalities.
• Metastatic disease occasionally manifests
as a solitary abnormality, usually in the
spine like in degenerative d/s. SPECT is

31. Metastatic Bone Disease ?
• Multiple Fractures
• Radiotracer
accumulation in both the
vertebral body and
pedicles usually indicates
metastatic disease, whereas
abnormalities that involve
the vertebral body and
facets but spare the
pedicles are usually benign
• Activity that is confined
to the vertebral body can
be due to tumor, trauma, or
infection

34. Metastatic Bone Disease

35. Flare Phenomenon
Usually occurs 3-6 months post chemotherapy

36. Flare phenomenon
• seen in patients who are responding to
treatment, reflects healing of the bone
lesions and has been described as the
“flare” phenomenon.
• This phenomenon is usually observed within
3 months after initiation of treatment and is
often associated radiographically with the
sclerotic changes that indicate healing.
• Continued increase in the number and
intensity of lesions beyond 6 months is
usually indicative of disease progression

38. Superscan
• When the metastatic process is
diffuse, virtually all of the radiotracer
is concentrated in the skeleton, with
little or no activity in the soft tissues or
urinary tract. The resulting pattern,
which is characterized by excellent
bone detail, is frequently referred to as
a superscan
• A superscan may also be associated
with metabolic bone disease. Unlike in
metastatic disease, however, the
uptake in metabolic bone disease is
more uniform in appearance and
extends into the distal appendicular
skeleton.

39. Hypertrophic
Osteoarthropathy
•linear tracer uptake
along the femurs,
tibias, and distal upper
extremitis (black
arrows)
•nonuniform, irregular
cortical uptake
involving the long
bones and giving rise
to the “tramline sign”

40. Osteosarcoma

41. Ewing Sarcoma

42. Multiple Myeloma
• lytic bone lesions
(bone formation is
markedly
suppressed or
absent)
• unless associated
fracture present
bone scan often
normal

43. Benign Bone Tumors
• Osteoid Osteoma (and
osteoblastoma)
• Enchondroma
• Osteochondroma
• Chondroblastoma

44. Osteoid Osteoma
– “double density” sign

45. Enchondroma
• typically only mildly increased
uptake unless secondary fractures
occur

46. Osteochondroma
• uptake on bone scan varies

47. Chondroblastoma
• uptake on bone scan varies

48. Skeletal Trauma
• 95% visualized by day 3, maximum
positivity by day 7 (age<65 y)
• advanced age, debilitation can cause
delayed or non-visualization
• return to normal depends:
– location and degree of damage
– age of patient
• patients age<65y: 60-80% of non-
displaced fx revert to normal in 1 year,
95% by 3 y)
• patients >65 year can remain positive

51. Stress Fractures
• radiograph can be negative
• occurs in normal bone that undergoes abnormal
stress (insufficiency fractures occur with normal
stress in bones that are weakened)
• most common sites are the femoral neck and
tibia.
• typical pattern is oval area of increased uptake
with long axis parallel to axis of bone

53. Shin Splints (Periostitis)
• exercise induced pain along medial or
posteromedial aspect of tibia
• associated with increased tracer uptake
• >1/3 of bone length
• middle to distal tibia
• usually bilateral (not necessarily symmetrical)
• microperiosteal tears (via Sharpey’s fibers)
• positive finding does not predict further injury

54. • Hyperperfusion and hyperemia are
typically present in acute stress fracture.
• Unlike in stress fractures, angiograms and
blood pool images are usually normal in
shin splints. Delayed bone images reveal
longitudinally oriented linear areas of
increased uptake of varying intensity that
involve one-third or more of the posterior
tibial cortex

56. Bone Infarction/AVN
• appearance depends on time course
– In the acute phase of vascular compromise,
no radiotracer is delivered to the bone tissue.
At scintigraphy, the affected part of the
bone appears as a photopenic defect.
– After revascularization, exuberant
osteoblastic repair manifests as intense
radiotracer uptake.
–Subsequently, when repair is complete,
radiotracer uptake may return to
baseline levels
• less sensitive than MRI

57. Legg-Calve-Perthes
• early imaging photon
deficient lesion
• increased activity with
healing (for months)

58. Osteomyelitis
• increased tracer uptake
– (except occasionally in children
paradoxically decreased secondary to
increased pressure in marrow space)
• skeletal scintigram for whole body
survey
• MRI very sensitive, but limited as survey
tool
• A combination of focal hyperperfusion,
focal hyperemia, and focally increased
bone uptake is virtually diagnostic for
osteomyelitis

59. Osteomyelitis vs Cellulitis
• MRI of limited value in the diabetic foot
• three phase bone scan for differentiation of
cellulitis vs OM
• non specific-similar pattern in:
–neuropathic joint
–gout
–acute fractures
–healing osteonecrosis
–RSD

60. • The first (dynamic) phase reflects the
relative amount of blood flow to the
area of interest, whereas the second
(blood pool) phase reflects the amount
of activity that has extravasated into
the tissues around the area of interest.
The third (delayed [bone]) phase
reflects the rate of bone turnover.
• The classic appearance of
osteomyelitis on three-phase bone
scans consists of focal hyperperfusion,
focal hyperemia, and focally increased

62. Plantar fascitis

63. Reflex Sympathetic
Dystrophy (complex
regional pain syndrome)
diffuse, uniformly
increased uptake
throughout the
affected
region

64. Prosthesis-Loosening vs
Infection
• increased uptake normal after surgery
–~1y w/ cemented, ~2-3y w/ non-cemented
• start w/ bone scan if negative no
infection or loosening
• if positive and unclear whether
loosening or infection consider Tc-
HMPAO-WBC scan to differentiate
Infection from loosening
l

65. loosening Infection

66. Bone Dysplasias
• Paget’s Disease
– accelerated rate of bone turnover
– excessive resorption and formation of bone
– intensely increased activity throughout the
involvedbones
– most common: pelvis
• Others
– fibrous dysplasia
– Osteognesis imperfecta
– Osteopetrosis
– Melorheostosis

68. Heterotopic ossification

69. Sources of error
• – Patient movement
• – Greater than necessary collimator-to-
patient distance
• – Imaging too soon after injection, before
the radiopharmaceutical has been optimally
cleared from soft tissues
• – Injection artefacts
• – Radiopharmaceutical degradation
• – Urine contamination or a urinary diversion
reservoir

70. • – Prosthetic implants, radiographic
contrast materials or other attenuating
artefacts which may obscure normal
structures
• – Homogeneously increased bony activity
(e.g. “super-scan”)
• – Restraint artefacts caused by soft-tissue
compression
• – Prior administration of a higher energy
radionuclide (131I, 67Ga, 111In) or of a
99mTc radiopharmaceutical which
accumulates in an organ that could

71. • – Significant findings outside the area of
interest may be missed if a limited study
is performed
• – Changing bladder activity during SPET
of the pelvic region
• – Purely lytic lesions
• – Pubic lesions obscured by underlying
bladder activity
• – Renal failure