nmt631 skeletal anat, phys, bone scinti principles
TRANSCRIPT
Skeletal system: Anatomy/Physiology/
Bone Scintigraphy Principles
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NMT 631
Overview of Skeletal Imaging
Review of Skeletal System
Clinical Indications
Radiopharmaceutical used
Dosage & Administration
Technique
The Normal Scan
Artifacts & Pitfalls
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What do they all have in common…?
• A 65 year old lady, after total hip replacement, now with persistent hip pain and doubtful x-rays
• An 18 year old basketball player with burning pain in the foot despite negative foot x-rays
• A 45 year old breast cancer patient with recent unexplained back and hip pain.
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….a visit to the Nuclear Medicine department for a:
Bone Scintigraphy(Bone scan)
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The Skeletal System• Axial skeleton
• Skull• Vertebral column• Thorax
• Appendicular skeleton• Shoulder girdle• Arms• Pelvic girdle• Legs
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Review of Skeletal System
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Review of Skeletal System
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Anterior
Posterior
Review of Skeletal System
Acetabulum
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Rev
iew
of S
kele
tal S
yste
m
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Review
of Skeletal System
1. Cranium (Skull)
3. S.I. Joint
4. Femur
5. Posterior
6. Scapula
7. Spine
8. Iliac crest
9. Pubis
10. Clavicle
11. Humerus
12. Neck of Femur
13. Mandible14. Sternum
15. Radius
16. Ulna
17. Tibia
18. Anterior
2. Rib
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Review of Skeletal System
Terminology
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• Anterior/Posterior
Anterior/Posterior
ANT
POST
R L
L R
Review of Skeletal System
Terminology continued…
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Plantar
• Proximal/Distal• Lateral/Medial• Superior/inferior• Palmar (volar)• Plantar
Review of Skeletal System
Bone Ultrastructure
• Detect/stage metastatic disease & follow-up• Evaluate primary bone neoplasms• Evaluate inflammatory vs. infectious diseases• Evaluate bone pain in pt with normal radiographs• Investigate unexplained, increased alkaline
phosphatase levels (enzyme used by osteoblasts to lay down bone matrix)
• Assess bone graft viability, infarction or aseptic necrosis
• Assess prosthetic joints for infection or loosening• Evaluation of roentgenologically difficult fractures
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Clinical Indications
Radiopharmaceutical used
Generic name Chemical name
• Tc-99m medronate Methylene (technetium) Di
Phosphonate (MDP)
• Tc-99m oxidronate HydroxyMethyleneDiphosPhonate(HDP or HMDP)
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15Mechanism of uptake - Chemisorption
• Pediatrics by weight : Recommended• 0.25 mCi/kg (pediatric dose)
Young’s rule or Webster’s rule for pediatric dosage calculation:
Age in years + 1Age in years + 7
Dosage
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Dosage & Administration
X Adult dose
20 – 30 mCi (adult dose) ( MBq)740 – 1110
Administration• Intravenous (i.v.)
Straight Stick -
- Butterfly
- existing i.v. catheter (with saline flush)
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Dosage & Administration
Patient preparation (before arrival)
Hydration
Frequent voiding
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Technique
Critical Organ - Bladder
Patient preparations (after arrival)
• Identify the patient; verify the physician’s order; review the clinical indication for the exam
• Explain exam to patient; obtain relevant medical history
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Technique
Relevant Medical History
• Bone pain• Trauma/fracture• Arthritis• Medications/dietary
supplements• Surgery• Malignancies• Biopsy/pathology
• Radiation/chemotherapy• Kidney/bladder problems• Recent dental work• Chronic health problems• Other medical imaging
results• Pregnancy status• Lab results
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Technique
Patient Preparation• Radiopharmaceutical
clearance depends on several factors, including:• Age• Renal status
• Ideal wait time:• 2 to 3 hours post inj
• Immediately before imaging:- remove attenuating materials- patient should void
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Technique
Imaging the patient
Use one of the following imaging techniques:
- Static studies
- Dynamic studies
- Multiphase studies (with 3-phase/ 4-phase)
- Tomographic studies (SPECT)
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Technique
Static studies
• Time delay post tracer injection
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• Preset total counts or time
• Whole body vs limited (“spot” view)
- Imaging localized concentration of radiopharmaceutical in the body
Technique
Dynamic Studies (Flow) - Multiple sequential Imaging of
nonlocalized radioactivity in the body usually yielding functional data
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Tech
niqu
e
(as in imaging blood flow, gastric emptying, kidney filtration, etc)
Multiphase Studies
• 3-Phase Study
Imaging in the following sequence:
1) Immediate flow dynamic images2) Early (5-15min) static image(s)3) Delayed (3-4hr) static image(s)
• 4-Phase Study: 3-phase study plus a 24 hour delayed image
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Technique
1st Phase (Perfusion)2nd Phase (Blood Pool)
3rd Phase (Delayed)
3-Phase bone scintigraphy
Technique
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Bone SPECT
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Technique
(single photon emission computed tomography)
• Multiple planar images taken around the body (projections)
Planar vs. Tomographic
Mathematically reconstructs 3-D volume from projection data using a computer
Bone SPECT (continued..)
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Transverse Slices (Top -> Bottom)
Sagittal Slices (Right -> Left)
Coronal Slices (Front -> Back)
Technique
The projection images are used to reconstruct slices in 3 different planes using computer
Bone SPECT Continued…
Advantages & Disadvantages
• Improves lesion detection• Better localizes abnormality suspected in
planar images• Most valuable in complex bony structures• Time consuming• Patient discomfort
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Technique
Normal Adult
• Symmetry
• Increased tracer concentration in the following areas:• nasopharynx• sternum• shoulder joints• anterior iliac crests• Posterior S.I. Joints
• Visualization of kidneys/bladder
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The Normal Scan
“Super Scan”
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There is minimal soft-tissue activity and virtually no renal or bladder activity. This pattern is indicative of diffuse bone metastases and is often referred to as a superscan.
Also associated with:-certain metabolic bone diseases- abnormally extended delay before imaging
Radiographics. 2003;23:341-358
Normal Child
• Tracer distribution is age dependent
• In addition to areas listed for adults, increased activity also noted in areas of bone growth:– epiphyseal plates– costochondral
junctions
The Normal Scan
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Bone Scintigraphy – Sensitivity vs. Specificity
Nuclear medicine bone imaging is very sensitive to pathologic changes in bone physiology (eg., bone destruction, changes in perfusion), but it is not specific for a particular disease.
Greater specificity is achieved by gathering more data about the patient such as clinical symptoms or the results of other diagnostic tests.
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The Abnormal Scan
Bone uptake principles• Recall that the skeleton undergoes constant
remodeling
• Radiopharmaceutical uptake in the bone is proportional to blood flow, bone mass, and metabolic activity N
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The Abnormal Scan
Pathology: - Increased tracer uptake (“hot spots”) - Decreased tracer uptake (“cold spots”
or photopenia)
Pathology Manifestations Pathological conditions
causing Increased Uptake
Neoplastic disease
Trauma sites
Metabolic bone disease
Degenerative bone diseaseInflammatory bone disease
Pathological conditions causing Decreased Uptake
Radiation injury
Avascular necrosis
Cyst
Multiple myeloma
Fluid collections
The Abnormal Scan
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Extraosseous Activity
• Renal anatomy & abnormalities
• Acute myocardial infarction
• Soft tissue inflammation
• Neoplastic soft tissue tumors
• Normal female breasts
• Amyloidosis
SPECT image shows pedicle uptake to be more superficial in overlying soft tissue (arrow). Patient had received injections of antiinflammatory drugs at this site a few weeks before scan.
Artifacts & Pitfalls
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Artifacts
• Attenuating objects
• “Free” pertechnetate
• Tracer infiltration
• Urine contamination
• Arterial injection Urine contamination (A) disappeared after patient removed cloths (B)
Artifact from an implanted
defibrillator.
Artifacts & Pitfalls
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Evaluate images for technical qualityUrine contaminationAttenuation artifactsPatient positioningTracer extravasation (infiltration)Other artifacts (radiopharmaceutical, equipment, patient)
Artifacts & Pitfalls
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Was image acquired at correct time following tracer administration?• Check radiopharmaceutical distribution• Look for soft tissue/blood clearance
Is the radiopharmaceutical distribution as expected?• Normal biodistribution• Pathology• Patient preparation
Does the image include all relevant anatomy?• Patient/camera positioning
Was the patient positioned correctly?• Relevant anatomy• Correct positioning
Were the correct acquisition parameters used?• Collimator• Static vs dynamic• Total counts, time or framing rate• Acquisition matrix (spatial resolution)
Are the images displayed and labeled correctly?• Format• Media (film, laser paper, workstation monitor)
Are there any artifacts that need to be explained or removed (require image to be repeated)?