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NM 4203 Scanning and Imaging

NM 4203 Scanning and Imaging. Central Nervous System. Anatomy and Physiology. CNS consists of the brain and spinal cord Brain divided into 4 parts: Cerebrum Cerebellum Diencephalon (thalamus & hypothalamus) Brain stem. Cerebrum ~ cerebral cortex gray matter.

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NM 4203 Scanning and Imaging

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  1. NM 4203Scanning and Imaging Central Nervous System

  2. Anatomy and Physiology • CNS consists of the brain and spinal cord • Brain divided into 4 parts: • Cerebrum • Cerebellum • Diencephalon (thalamus & hypothalamus) • Brain stem

  3. Cerebrum ~ cerebral cortex gray matter • Frontal, temporal, parietal and occipital lobe

  4. Anatomy and Phsiologoy • Ventricles: cavities in the brain ~ filled with Cerebrospinal fluid (CSF) • What is CSF? • Produced in the choroid plexus of the lateral ventricles • Clear liquid • Protects the brain from shocks • Delivers nutrients • Removes waste from brain & spinal cord • 400 – 500 ml/ day is formed

  5. Ventricles

  6. Anatomy and Physiology • Brain is metabolically active • Requires continual supply of oxygen & glucose • Blood-Brain barrier • Protects the brain from toxic substances • Broken by injury or disease

  7. Planar Imaging • Brain Death • 99mTc Pertechnetate (15-20 mCi) • (can also use HMPAO or 99mTc DTPA) • Image blood flow immediately with bolus injection • Brain death: Complete absence of cerebral perfusion. No activity seen in arteries and veins. • Typical pattern shows blood flow through external cerebral circulation but stops before cerebral cortex. No filling of sagittal and transverse sinuses.

  8. Normal brain flow & Statics

  9. Brain death

  10. CSF Leak • In 111 DTPA is injected in subarachnoid space • Image immediately over injection site • Routine images at 6,24,48,72 + hrs. • Anterior and lateral views of head.

  11. CSF Leak

  12. CSF Leak w/quantitative results • CSF rhinorrhea • Pledgets placed by otorhinolaryngologist • Removed 6 hrs after injection • Well counter is used to count pledgets and plasma samples from patient • Normal pledget to plasma ratio is 1:1.3

  13. Radionuclide Cisternogram • Hydrocephalus • In 111 DTPA injected into subarachnoid space during lumbar puncture. • Normal: activity seen in the basal cisterns by 3hrs. No reflux into the ventricles.

  14. Normal Cisternogram

  15. Communicating Hydrocephalus

  16. Radiopharmaceuticals for SPECT • 99mTc HMPAO (exametazime or Ceretec) ~ 10-20 mCi • Crosses the blood-brain barrier • Remains trapped in the brain proportional to the cerebral blood flow • 99mTc ECD ( bicisate or Neurolite) ~ 10-20 mCi • Crosses the blood-brain barrier • More stable than HMPAO • Images cerebral blood flow • Less background activity

  17. SPECT • Room quiet and low light to minimize environmental effect on distribution of radiopharmaceutical. Pt. should relax and remain quiet for 20 min after injection.

  18. Clinical Indications for SPECT or PET • Cerebrovascular disease / Stroke / TIA’s • Tumors • Epilepsy • Parkinson’s disease • Dementia / Alzheimer’s disease • Brain death assessment • Effectiveness of surgery or radiation therapy

  19. PET Brain Imaging • 10 mCi 18F FDG • 5 min before and 30 minutes following injection: • Pt. told to sit quietly, do not cross arms or legs, room lights low, eyes covered and ear plugs in. • This is to reduce sensory stimulation in the brain.

  20. PET : Transaxial, Coronal, Sagittal Plane

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