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Download Body-Section Radiography
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Advantages of MRI • Higher resolution of tissues • No ionizing radiation • Multiplanar imaging Disadvantages of MRI • Long imaging time • Hazards with ferromagnetic metals (pacemakers, vascular clips, etc) • Claustrophobia • Higher cost Relative Brightness of Tissues Fat Marrow Brain Muscle Body Fluid TMJ Disk Cortical Bone Air White Gray Black Nuclear Medicine Nuclear Medicine • Radioactive compounds • Target tissues • Radioactive agents pools in the target tissues • Detected and imaged by external detectors (gamma camera). 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 Technetium • 99mTcO4- - thyroid and salivary gland scan • 99Tc phosphate - bone scan • Is this an active disease? 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 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 Cephalometric Radiography Contrast Agents Contrast Agents • Radiopaque materials • Water soluble • Fat soluble • 28 – 38% iodine Phases of Sialography • Ductal • Acinar • Evacuation Indications of Sialography • Acute swelling secondary to ductal obstruction • Recurrent Inflammation • Palpable salivary gland mass • Autoimmune Sialadenitis Contraindications of Sialography • Sensitivity to contrast agents • Acute Sialadenitis • Limited use in tumor diagnosis Scintigraphy Sialography Radioactive material Radiopaque material Through blood stream All glands imaged at the same time Imaged by gamma camera Through duct One gland at a time Imaged by fluoroscopy Contrast Studies: Arthrography 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 Contrast Material Injection Open Position • Translation of condyle • Reduction of disk
