Advantages of MRI

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Advantages of MRI

• Higher resolution of tissues
• No ionizing radiation
• Multiplanar imaging

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Disadvantages of MRI

• Long imaging time
• Hazards with ferromagnetic metals (pacemakers,
  vascular clips, etc)
• Claustrophobia
• Higher cost

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Relative Brightness of Tissues

• Fat White
• Marrow
• Brain
• Muscle Gray
• Body Fluid
• TMJ Disk
• Cortical Bone
• Air Black

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Nuclear Medicine
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Nuclear Medicine

• Radioactive compounds
• Target tissues
• Radioactive agents pools in the target tissues
• Detected and imaged by external detectors (gamma
  camera).

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Nuclear Medicine

• Shows structure and function of the target
  tissues
• Static and dynamic conditions
• Scintigraphy scans or RN (radionuclide) scans
• Bone scans or salivary gland scans

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Technetium

• 99mTcO4- - thyroid and salivary gland scan
• 99Tc phosphate - bone scan

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• Is this an active disease?

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Phases of Salivary Gland Scan

• Flow phase
• Five to 10 mCi of 99mTcO4
• first 30 to 120 seconds
• shows flow of blood
• Concentration phase
• next 30 to 45 minutes
• demonstrate the anatomy and function
• Washout Phase
• administer sialagogue
• demonstrates secretory capabilities

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Cephalometric Radiography

• Reproducible and standardized views
• For measurements and assess growth
• Fixed source to film distance 60 inches
• Cephalostats and earplugs help in reproducible
  positions

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Cephalometric Radiography
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Contrast Agents
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Contrast Agents

• Radiopaque materials
• Water soluble
• Fat soluble
• 28 38 iodine

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Phases of Sialography

• Ductal
• Acinar
• Evacuation

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Indications of Sialography

• Acute swelling secondary to ductal obstruction
• Recurrent Inflammation
• Palpable salivary gland mass
• Autoimmune Sialadenitis

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Contraindications of Sialography

• Sensitivity to contrast agents
• Acute Sialadenitis
• Limited use in tumor diagnosis

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Scintigraphy Sialography
Radioactive material Radiopaque material
Through blood stream Through duct
All glands imaged at the same time One gland at a time
Imaged by gamma camera Imaged by fluoroscopy
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Contrast Studies Arthrography
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Arthrography

• Contrast media is introduced in joint spaces
• Upper vs. lower joint space
• Viewed by Image Intensifier Fluoroscopy
• Video recording allows study of joint movement

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Contrast Material Injection
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Open Position

• Translation of condyle
• Reduction of disk