Skeletal scintigraphy covering the whole possible bone diseases to diagnosis.

1. Dr. Mustafa Ahmed Alazam
Tehran university of medical sciences
Research center for Nuclear medicine
National center of excellence
Shariati hospital
Skeletal scintigraphy

2. let’s the isotopes solve the
difficulty

3. Topics:
Part one: Introduction and imaging procedure:
 What is Bone Scintigraphy?
 Sensitivity and Specificity.
 Radiopharmaceuticals.
 Uptake and Pharmacokinetics
 Normal Tc-99m MDP WBBS
 Imaging Protocol of Tc-99m MDP
 Preparation.
 The protocol.
 Bone-Scan Applications.
Part Two: Metastatic diseases.
Part Three: Traumatic, metabolic diseases, inflammation and benign conditions.

5. What is Bone Scintigraphy?
Bone scan is one of the most commonly performed procedures in nuclear
medicine.
Bone scan often provides an earlier diagnosis and demonstrates more lesions than
are found by radiographic procedures. Scintigraphic image quality has improved
dramatically over time, due to advances in camera detector technology and processing
software. Accuracy is also improved through the use of three-dimensional (3-D) single-
photon emission computed tomography (SPECT). In addition, as uptake may be the result of
many different processes, CT correlation can be used to explain the etiology of nonspecific
abnormal activity. Fusing the CT to the SPECT is especially helpful in correcting the low
specificity of the bone scan. This fusion will very often be better when images are acquired
on a hybrid SPECT/CT scanner.

6. Sensitivity and Specificity
• Bone scan is very sensitive study but it is not specific.
• Although findings on bone scan are non-specific, its monostotic or polyostotic
status and anatomical distribution can provide important clues to the differential
diagnosis.
• Because of its ability to image the entire skeleton with high sensitivity at a
reasonable cost, it remains widely used decades after its introduction, despite
technological advances in CT and magnetic resonance (MR) imaging.

7. They are bone seeking agents. They are labeled with Tc99m. They are phosphate
analogs.
Most commonly used one is MDP ( Methylene Diphosphonates) and the HDP
(Hydroxy methylene diphosphonates).
It is a highly versatile examination, able to assess the effects of tumor, infection,
trauma, arthritis, and metabolic bone disease.
Radiopharmaceuticals

8. Technetium-99m MDP
The combination of Tc-99m with a phosphate analog carrier molecule creates an agent that can
demonstrate skeletal turnover. Initially, pyrophosphates (Tc-99m PYP) were used, characterized
by their P–O–P bond. However, agents containing a diphosphonate structure were ultimately
found superior: Their P–C–P bond is more stable and allows faster background clearance
by renal excretion. Tc-99m hydroxymethylene diphosphonate (Tc-99m HMDP or HDP) and Tc-
99m methylene diphosphonate (Tc-99m MDP) are both able to demonstrate a high level of
detail, although Tc-99m MDP is more commonly used.

9. The injected Tc-99m MDP rapidly distributes into the extracellular fluid and is quickly taken up
into bone.
Although accumulation relates to the amount of blood flow to a region, uptake is primarily the
result of osteogenic activity, being much higher in areas of active bone formation and repair
than in mature bone.
Tc-99m MDP binding occurs by chemisorption in the hydroxyapatite mineral component of the
osseous matrix. Accumulation in areas of amorphous calcium phosphate may account for the
Tc-99m MDP uptake sometimes seen in sites outside the bone, such as dystrophic soft tissue
ossification.
Decreased activity is seen in areas of reduced or absent blood flow or infarction. Diminished
uptake or cold areas are also often seen in lytic metastases.
Uptake and Pharmacokinetics

10. Approximately 50% of the dose is localized to the bone, with the remainder excreted
by the kidneys.
Although peak bone uptake occurs approximately 1 hour after injection, the highest
target-to-background ratios are seen after 6 to 12 hours.
Images are typically taken at approximately 3 hours to balance the need for
background clearance with the relatively short 6-hour half-life of Tc-99m and patient
convenience.
Also, the radiotracer half-life limits imaging to a maximum of 24 hours after injection.

13. Routine bone scan (single phase at 2-4 hrs.)
Usually performed in cancer patients for osseous metastasis.
Three-phase or triple-phase bone scan
Recommended for evaluation of bone pain of unknown causes or diseases
that may affect blood flow eg. Inflammatory conditions.
Bone Scan: Techniques

15. PREPARATION
Position gamma camera immediately over area of concern.
RADIOPHARMACEUTICAL ADMINISTRATION
Bolus intravenous injection of Tc-99m MDP
VASCULAR PHASE
Obtain dynamic 2- to 5-second images for 60 seconds
BLOOD POOL or SOFT-TISSUE PHASE
Obtain immediate static images for time (5 minutes) or counts (300k).
SKELETAL PHASE (Delayed 3-hr)
Delayed 300k-1000k images at 2 to 4 hours.
Three-phase bone scan (3PBS)

17. Bone Scan : FP & FN

18. Bone-Scan Applications

21. Scintigraphic Patterns in Metastatic Disease

22. Typical findings:
Multiple randomly distributed areas of
abnormal increased uptake, varying
in size, shape, and intensity.
Axial skeleton*
Multiple bone metastases

23. DDx Cold defects on bone scan
Bone metastases
Metal artifact (pacemaker, prosthesis)
Radiation changes
Early avascular necrosis
Early infarct
Benign tumors, cysts

24. Cold defects on
bone scan:
Not bone
metastasis

28. Post Rx bone scan shows increase in intensity and looks like progressive metastasis.
but it actually represents increased reparative process due to therapeutic
response*.
•This phenomenon may last upto 3-6 months post systemic treatment eg. CMT,
hormonal Rx.
•Early change on bone scintigraphy a marker for a successful cancer treatment.
•F/U bone scan 6 months after treatment more accurate.
Flare Phenomena

30. Super scan
-“Super scan” is intense symmetric activity in
the bones with diminished renal and soft
tissue activity.
-This findings may be called as “beautiful
bone scan”
Common cancers: Prostate, lung, breast

31. Metabolic causes
Hyperparathyroidism
Renal osteodystrophy
(alteration of bone morphology
in patients with CKD)
Diffuse metastases
Prostate
Lung
Breast
Generalized increased uptake in bone scans
(Superscan)

32.  Axial skeleton
 Expansile bony lesions
 Presence of photopenic areas due to osteolytic lesion
Patterns that are suggestive for bone metastases

34. Up to 50% of patients dying from a primary lung cancer have osseous metastasis at autopsy.
Bone is a common site of metastatic cancer spread in NSCLC patients (20–40%), comparable in
frequency to liver (25–30%) and the contralateral lung (40–50%)
Also, increased cortical activity, prominent in the extremities, can be seen in lung cancer as a
result of hypertrophic osteoarthropathy.
Thus, bone scans are not generally performed in patients with stage I or II disease. However,
initial bone scan is helpful for subsequent bone scan evaluation.
Skeletal scintigraphy is highly sensitive in breast cancer.
Abnormal soft tissue activity can be seen from tumor in the breast, metastatic disease in the
liver, and in malignant pleural effusions.
Cancer Types:

35. PSA < 10 ng/ml  < 2 % bone metastasis
PSA < 20 ng/ml  2-10% bone metastasis
Very low risk to have bone metastasis from prostate cancer.
Patients with normal alkaline phosphatase levels, PSA level <10, and a Gleason
score <6 represent
Patients with a PSA <10, Gleason score ≤6, and T2 prostate cancer:
Low risk
Patients with elevated alkaline phosphatise level, PSA <10, and a Gleason score
<6.
Bone imaging may be appropriate.
Patients with PSA = 10 - 20 or a Gleason score =7 with a predominantly Gleason 4
pattern.
Patients with PSA < 10, Gleason score =7, and T2 prostate cancer, especially with
a dominant Gleason 4 pattern.
Prostate cancer

36. 80% of the cases with sternal lesions 
sternal metastasis
Breast Cancer with Sternal metastasis
Sternal metastasis & left malignant pleural effusion

37. (A) Anterior and posterior whole-body images of a
patient with breast carcinoma have the advantage
of depicting the entire skeleton in a single view. Note the
abnormal activity in one of the lower left ribs.
(B) High-count-density left posterior oblique spot view of
the same patient. The location and appearance of
lesions are often clearer on the spot view. In this case,
the lesion tracking along the rib is classic for a metastatic
lesion.

38. Abnormal mild uptake in the distended
abdomen is characteristic
of malignant ascites on bone scan.

39. Prostate cancer metastatic disease. (A) Numerous foci of increased activity, largely in the axial
skeleton. (B) Two years later, with disease progression, diffuse increased activity is seen in the
spine, ribs, and pelvis, and multiple new lesions are seen in the skull and proximal long bones.
In some areas such as the pelvis, the bones appear almost normal in a pattern referred to as a
superscan or a beautiful bone scan, corresponding to the now nearly confluent sclerotic lesions
that had also visibly progressed on computed tomography (CT).

41. Traumatic fractures
Occult fractures
Vertebral compression fractures: traumatic vs osteoporotic fractures.
Stress fractures, hardly seen on early plain radiograph, bone scan is more sensitive.
Fatigue fractures: sport injury
Insufficiency fractures: sacrum
Trauma

42. Rib Fractures
Most fractures show early increase in activity as a result of hyperemia and inflammation.
Repair begins within a few hours and reaches a maximum in 2 to 3 weeks.
Rib fractures arranging as a linear pattern in consecutive ribs.
Time after Fracture at which Bone Scan Becomes Abnormal

45. This athlete had bilateral lower leg pain.
A, Vascular phase is normal
B, Blood pool image is also normal. (normally a lot of blood flow to the calf muscles.)
C and D, On delayed 3-hour images, there is increased activity (arrows) in a long
linear distribution of the osteromedial tibial shafts.
3PBS: Shin Splints

46. Sacral insufficiency fracture: Honda sign
Posterior spot view of a patient with osteoporosis.
The patient has a characteristic H-type pattern of a sacral insufficiency fracture with a
horizontal band of increased uptake across the body of the sacrum and bilaterally
increased uptake in the sacral alae

49. Osteomyelitis of the right clavicle.
Anterior scintigram in a
child showing that the uptake on the
right is markedly greater than in
the left clavicle.

50. Three-phase bone scan may be highly useful when magnetic resonance (MR) is limited, as in this
case of a 34-year-old with prior reduction of a talar and fifth metatarsal fracture 2 years prior, with new
pain and swelling. (A) T1-weighted sagittal ankle MR is limited by metal susceptibility artifact (arrows).
(B) Blood flow and (C) soft tissue activity are increased in the areas of prior surgery, as is the delayed image
(D). Subsequent positive white blood cell and normal sulfur colloid marrow studies of the region confirmed
the presence of osteomyelitis.

55. Hypertrophic Osteoarthropathy (HOA)
Symmetric linear increase in tracer accumulation along
diaphyseal and metaphyseal surfaces of long bones
"tram-track" appearance
- Periostitis: metaphyseal and
diaphyseal regions of long
bones show smooth
periosteal reaction
- With disease progression 
periostitis extend to epiphysis