Unformatted text preview: BONE ISOTOPE SCAN
الدكتور قصي المقبل
أستاذ مشارك- قسم الشعة والطب
كلية الطب-جامعة العلوم والتكنولوجيا
Introduction 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. Sensitivity and Specificity
Sensitivity Bone scan is very sensitive study but it is
not specific. Although findings on bone scan are nonspecific, its monostotic or polyostotic
status and anatomical distribution can
provide important clues to the differential
Radiopharmaceuticals They are bone seeking agents. They are labeled with Tc99m. They are phosphate analogs. Most commonly used one is HDP
(Hydroxy Methylene Diphosphonates).
(Hydroxy They are given intravenously. Mechanism of Localization
Mechanism Phosphate groups bind to the hydroxyapatite
[Ca3(Po4)2] structure of bone tissue by a
mechanism called chemisorption.
mechanism The hydroxyapatite structure of the bone is
exposed during bone remodeling. So, more
radiopharmaceutical will deposit in that region
giving “hot” area.
giving 50-60% of injected dose localized on bone,
remain dose is cleared by kidneys.
remain Whole body bone scan
Whole This is the bony phase of bone scan. Inject radiopharmaceutical and image in
2-4 When we say bone scan, we usually
mean whole body bone scan. Three Phase Bone Scan
Three It is done to see if there is soft tissue
hyperemia. First phase is the perfusion phase or
vascular Second phase is the blood pooling phase
or soft tissue phase.
or Third phase is the bony phase. First Phase
First 30-60 dynamic images are usually
obtained over 1 minute immediately after
injection. This is radionuclide angiography and gives
an idea about the local vasculature. During
the first minute after injection, injected
dose is still intravascular. Perfusion
Perfusion Second Phase
Second Static image is obtained in 5 minutes after
dose Within 5 minutes post injection,
radiopharmaceutical moves from
intravascular space to extravascular space
(soft tissue). It gives idea about soft tissue
edema. Blood Pool
Hyperemia If there is focal increased activity in
the first and second phases,
hyperemia or acute inflammatory
process is present.
process Third Phase
Third It is the bony phase image obtained in
2-4 hours post injection.
2-4 It is the same as whole body bone
scan. Clinical Applications
1- Primary bone cancer
12- Secondary metastatic bone disease
Stress Primary Bone Malignancy
(Sarcomas) MRI provides more exact information
regarding tumor extent, particularly in soft
tissue. So, bone scan is not a diagnosis
image in primary bone tumors.
image Bone sarcomas-cont..
Bone Bone scan is a staging and restaging
image in bone sarcomas. It is performed
to see if there is bone metastatic disease
(bone to bone).
(bone 40 – 50% of patients with either Ewing’s
sarcoma or osteosarcoma develop
osseous metastases within 2 years of
presentation. Metastatic Bone Disease
Metastatic Bone scan is an extremely important tool
in decision making during management of
cancer Any cancer potentially could cause bone
metastatic disease. However, prostate, breast and lung
cancers have propensity to metastasize to
bone. Metastatic Bone Disease and
Bone About 80% of patients with known cancer
and bone pain have metastases
documented by bone scan.
documented 30 – 50% of patients with metastatic bone
disease do not have bone pain. Metastatic Bone Disease and
Image The hallmark of metastatic bone
disease is multiple foci of increased
osteoblastic activity in bony skeleton.
However, single lesion could be also
metastatic. Stress Fractures
Stress It is often difficult to visualized on a plain
radiograph. Fractures may be identified by bone scan
as early as 24 hours after occurrence.
as 3-phase bone scan is usually done.
3-phase There is hyperemia and osteoblastic
process (three phases are positive).
process Stress Fracture
Anterior Posterior Left Lat Right Lat Blood Pool
Anterior Posterior Left Lat 2 hour delay Right Lat Stress Fracture
Stress Acute Osteomyelitis
Acute Early plain radiography signs of
osteomyelitis are non-specific.
osteomyelitis 3-phase bone scan is usually the
procedure of choice to differentiate
between osteomyelitis and cellulitis.
between Acute Osteomyelitis-cont..
Acute If first and 2nd phases are positive
(hyperemia) with normal third phase,
diagnosis would be cellulitis.
diagnosis In acute osteomyelitis all 3-phases
are positive (hyperemia and
osteoblastic process in the bone).
Perfusion Blood Pool
Blood Whole Body
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- Fall '08
- Oncology, Bone Disease, bone scan, metastatic bone disease