SKELETAL RADIONUCLIDE IMAGING

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SKELETAL RADIONUCLIDE IMAGING
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• Dr. Hussein Farghaly
• Nuclear Medicine Consultant
• PSMMC

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CONTENTS

• Bone and BM physiology anatomy
• Bone scan
• Radiopharmaceutical,
• preparation,
• uptake and pharmacokinetics
• dosimetry,
• protocols,
• normal and altered distribution
• Clinical indication and Skeletal pathology
• Bone Marrow scan

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Objectives
I -ANATOMY Physiology of Bone

• Understand the anatomy/histology of bones
• Understand the importance of bones as it relates
  to physiology
• Hormonal regulation of bone function
• Significance of bones with metabolism

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Parts of the Skeletal System

• Bones are made of several tissues
• Primarily made of collagen and hydroxyapatite -
  Ca10(PO4)6(OH)2
• About 206 bones in the human body
• Axial skeleton
• Skull and bones that support it
• Includes vertebra and ribs
• 80 bones
• Appendicular skeleton
• Limbs
• 126 bones

• Appendicular skeleton
  Axial skeleton

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Bone Physiology
www.ama-assn.org
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Features of a Long Bone Epiphysis Ends of the
bone. Diaphysis The shaft of the bone which
surrounds the medullary cavity. Articular
Cartilage Cover the ends of the bones and
allows for smooth movement. Epiphyseal
Plate Areas made of cartilage allowing for the
growth of the bone.
Periosteum hard outer covering Cells for growth
and repair Compact bone hard strong layer Bone
cells, blood vessels, protein with Ca and
P Spongy bone at ends of long bones Has small
open spaces to lighten weight Marrow cavity
hollow in middle of long bones
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Bone Marrow

• Red marrow produces blood cells and clotting
  factors
• Found in humerus, femur, sternum, ribs,
  vertebrae, pelvis
• Produces RBC 2 million per second
• Yellow marrow stores fat
• Found in many bones

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Change of Bone marrow distribution in long bones
by age
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Joints

• Where bone meets bone
• Ligament holds bone to bone
• There is fibrous and synovial joints
• Types of joints
• Immovable - skull
• Ball-and-socket - shoulder
• Hinge - knee
• Pivot forearm
• Gliding - vertebrae

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Joints cont.

• Cartilage covers ends of movable bones
• Reduces friction
• Lubricated by fluid from capillaries

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Functions of Skeletal System

• SUPPORT Hard framework that supports and
  anchors the soft organs of the body.
• PROTECTION Surrounds organs such as the brain
  and spinal cord.
• MOVEMENT Allows for muscle attachment therefore
  the bones are used as levers.
• STORAGE Minerals (Ca P) and lipids (TG3 in
  yellow BM) are stored within bone material.
• BLOOD CELL FORMATION In some bones, red bone
  marrow (a connective tissue) produces
  erythrocytes, leucocytes and platelets, via a
  process called haemopoiesis.

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Histology of bone tissue

• Like other connective tissues, bone is a matrix
  containing cells as opposed to a structure made
  of cells
• The matrix is made of hydroxyapatite which is
  predominately tricalcium phosphate
• Ca3 (PO4)2

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Bone cells

• As for all connective tissue, bone consists of
  cells and extracellular matrix. 
• There are three types of cells in mature bone
  tissue 
• Osteoblasts
• Osteocytes
• Osteoclasts

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Function

• Osteoblasts and osteocytes are involved in
  deposition of bone matrix
• Osteoblasts are located at the surface of bone
  tissue, whereas osteoclasts are located within
  the calcified matrix 
• Osteoclasts are involved in the resorption of
  bone tissue. 

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Hormones affecting growth

• Parathyroid hormone and 1,25-dihydroxyvitamin D3
  stimulate bone resorption.
• Calcitonin inhibits bone resorption.

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Bone Remodeling

• Remodeling units adjacent osteoblasts and
  osteoclasts deposit and resorb bone at periosteal
  and endosteal surfaces

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Bone Deposition

• Occurs where bone is injured or added strength is
  needed
• Requires a diet rich in protein, vitamins C, D,
  and A, calcium, phosphorus, magnesium, and
  manganese
• Alkaline phosphatase is essential for
  mineralization of bone

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Bone Resorption

• Accomplished by osteoclasts
• Resorption bays grooves formed by osteoclasts
  as they break down bone matrix
• Resorption involves osteoclast secretion of
• Lysosomal enzymes that digest organic matrix
• Acids that convert calcium salts into soluble
  forms
• Dissolved matrix is transcytosed across the
  osteoclasts cell where it is secreted into the
  interstitial fluid and then into the blood

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Importance of Ionic Calcium in the Body

• Calcium is necessary for
• Transmission of nerve impulses
• Muscle contraction
• Blood coagulation
• Secretion by glands and nerve cells
• Cell division

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Control of Remodeling

• Two control loops regulate bone remodeling
• Hormonal mechanism maintains calcium homeostasis
  in the blood
• Mechanical and gravitational forces acting on the
  skeleton

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Hormonal Mechanism

• Rising blood Ca2 levels trigger the thyroid to
  release calcitonin
• Calcitonin stimulates calcium salt deposit in
  bone
• Falling blood Ca2 levels signal the parathyroid
  glands to release PTH
• PTH signals osteoclasts to degrade bone matrix
  and release Ca2 into the blood

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Hormonal Mechanism
Figure 6.12
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Response to Mechanical Stress

• Wolffs law a bone grows or remodels in
  response to the forces or demands placed upon it
• Observations supporting Wolffs law include
• Long bones are thickest midway along the shaft
  (where bending stress is greatest)
• Curved bones are thickest where they are most
  likely to buckle

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Response to Mechanical Stress
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Bone Fractures (Breaks)

• Bone fractures are classified by
• The position of the bone ends after fracture
• The completeness of the break
• The orientation of the bone to the long axis
• Whether or not the bones ends penetrate the skin

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Types of Bone Fractures

• Transverse the fracture is perpendicular to the
  long axis of the bone
• Compound (open) bone ends penetrate the skin
• Simple (closed) bone ends do not penetrate the
  skin

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Common Types of Fractures

• Comminuted bone fragments into three or more
  pieces common in the elderly
• Spiral ragged break when bone is excessively
  twisted common sports injury
• Depressed broken bone portion pressed inward
  typical skull fracture
• Compression bone is crushed common in porous
  bones

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Common Types of Fractures

• Epiphyseal epiphysis separates from diaphysis
  along epiphyseal line occurs where cartilage
  cells are dying
• Greenstick incomplete fracture where one side
  of the bone breaks and the other side bends
  common in children

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Common Types of Fractures
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Common Types of Fractures
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Common Types of Fractures
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Stages in the Healing of a Bone Fracture

• I- Hematoma formation
• Torn blood vessels hemorrhage
• A mass of clotted blood (hematoma) forms at the
  fracture site
• Site becomes swollen, painful, and inflamed

Hematoma
Hematoma formation
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Stages in the Healing of a Bone Fracture

• II- Fibrocartilaginous callus forms
• Granulation tissue (soft callus) forms a few days
  after the fracture
• Capillaries grow into the tissue and phagocytic
  cells begin cleaning debris

External callus
New blood vessels
Internal callus (fibrous tissue and cartilage)
Spongy bone trabeculae
Fibrocartilaginous callus formation
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Stages in the Healing of a Bone Fracture

• The fibrocartilaginous callus forms when
• Osteoblasts and fibroblasts migrate to the
  fracture and begin reconstructing the bone
• Fibroblasts secrete collagen fibers that connect
  broken bone ends
• Osteoblasts begin forming spongy bone
• Osteoblasts furthest from capillaries secrete an
  externally bulging cartilaginous matrix that
  later calcifies

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Stages in the Healing of a Bone Fracture

• III- Bony callus formation
• New bone trabeculae appear in the
  fibrocartilaginous callus
• Fibrocartilaginous callus converts into a bony
  (hard) callus
• Bone callus begins 3-4 weeks after injury, and
  continues until firm union is formed 2-3 months
  later

Bony callus of spongy bone
Bony callus formation
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Stages in the Healing of a Bone Fracture

• IV- Bone remodeling
• Excess material on the bone shaft exterior and in
  the medullary canal is removed
• Compact bone is laid down to reconstruct shaft
  walls

Healing fracture
Bone remodeling
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