Ct scan interpretation

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Ct scan interpretation

  1. 1. Basic Interpretation of CT Scan Hon-Man Liu 廖漢文
  2. 2. Basic Interpretation of CT Scans Most of the CT pictures are non- specific CT pictures are depending on the density of the structures.
  3. 3. Principles of CT Diagnosis • Pre-contrast study • Post-contrast study • Change in adjacent structures • Clinical Information • Biological or anatomical characteristics
  4. 4. Pre-contrast study of CT • Hypo - density Comparison with CSF and brain tissue • Hyper - density Comparison with cranium bone • Iso - density As brain parenchyma • Hetero- density
  5. 5. Hypo-density in CT Higher than CSF but lower than brain tissue tumor, abscess, resolving hematoma, evolution infarct, protein, blood, debris
  6. 6. Hypo-density in CT Higher than CSF but lower than brain tissue
  7. 7. Hypo-density in CT Iso-density to CSF chronic hematoma, chronic infarct, porencephaly, congenital cyst, encephalomalacia change Water-like content
  8. 8. Hypo-density in CT Iso-density to CSF
  9. 9. Hypo-density in CT Lower than CSF • fat or cholesterol congenital tumor: dermoid , epidermoid,lipoma, • air head injury, pneumocephaly • myxoid
  10. 10. Hypo-density in CT Lower than CSF
  11. 11. Hyper-density in CT Comparison with bone • Iso- or higher than bone ossification, calcification, metallic, iatrogenic, blood pooling • Less than bone but higher than brain tissue hemorrhage, compacted cellularity
  12. 12. Hyper-density in CT Iso- or higher than bone
  13. 13. Hyper-density in CT Less than bone but higher than brain tissue
  14. 14. Post-contrast CT Enhancement patterns • gyral, ribbon, cortical • soild • rim or ring • mural nodular • linear and dot • heterogenous • no enhancement
  15. 15. Enhancement Patterns
  16. 16. Change in Adjacent Structures in CT • Edema • Bone • Ventricles, sulci and cistern
  17. 17. Edema Pattern in CT • Vasogenic edema tumors, infection, late infarct along the white matters, finger-like • Interstitial edema periventricular white matter, ependymitis granularis • Cytotoxic edema ischemia or infarct, gray matter
  18. 18. Vasogenic Edema
  19. 19. Vasogenic edema
  20. 20. Cytotoxic Edema
  21. 21. CAUSES of RAISEDCAUSES of RAISED INTRACRANIAL PRESSUREINTRACRANIAL PRESSURE HydrocephalusHydrocephalus BrainBrain edemaedema S.T.LS.T.L TumorTumor,, HematomaHematoma,, CytsCyts,, InfarctInfarct……..
  22. 22. RAISED INTRACRANIALRAISED INTRACRANIAL PRESSUREPRESSURE ICPICP DAYSDAYS WEEKSWEEKS HOURSHOURS ConingConing Focal mass effectFocal mass effect CSF spaceCSF space changechange hydrocephalushydrocephalus HerniationHerniation DEATHDEATH
  23. 23. HerniationHerniation Subfalcine Parahippocampus Central, tonsillar
  24. 24. SUBFALCINE HERNIASUBFALCINE HERNIA
  25. 25. TRANSTENTORIAL HERNIASTRANSTENTORIAL HERNIAS 1. PARAHIPPOCAMPAL GYRUS (PHG) HERNIATION 2. CENTRAL/DIENCEPHALIC HERNIATION MAY OCCUR INDEPENDENTLY ORMAY OCCUR INDEPENDENTLY OR IN COMBINATIONIN COMBINATION
  26. 26. PARAHIPPOCAMPAL GYRUSPARAHIPPOCAMPAL GYRUS (PHG) HERNIATION(PHG) HERNIATION
  27. 27. COMPLICATIONS of PHGCOMPLICATIONS of PHG HERNIATIONHERNIATION
  28. 28. COMPLICATIONS of PHGCOMPLICATIONS of PHG HERNIATIONHERNIATION PCA ossculsion 3rd nerve palsy
  29. 29. CENTRAL HERNIATIONCENTRAL HERNIATION MAMILLARYMAMILLARY BODYBODY PONSPONS
  30. 30. CENTRAL HERNIATIONCENTRAL HERNIATION NORMALNORMAL HERNIAHERNIA AP diameter > trans diameter AP diameter =/< trans diameter
  31. 31. SECONDARY BRAINSECONDARY BRAIN STEMSTEM HAEMORRHAGESHAEMORRHAGES Duret hemorrahge
  32. 32. CEREBELLAR TONSILAR HERNAITIONCEREBELLAR TONSILAR HERNAITION CONINGCONING OROR
  33. 33. Bone Change in CT • Foramen internal auditory canal, foramen ovale, orbital fissures • Cranium bone hyperostosis
  34. 34. CSF Spaces Change in CT • Widening or obliterated • Sensitive to mass effect • Proportional or in-proportional
  35. 35. • Ischemia: gray matter increased water -- density -- density closed to white matter -- loss of the differentiation between the lentiform nucleus and internal capsule CT of Cerebral Ischemia (lentiform nucleus sign)
  36. 36. CT of Cerebral Ischemia (Insular ribbon sign) Ischemia -- cytotoxic edema -- cellular swelling -- mass effect -- straightening the normal waving insular ribbon
  37. 37. CT of Cerebral Ischemia (Hyper-dense vascular sign) • Ischemia -- blood stasis in great vessel such as M1 - - blood clot -- high density
  38. 38. Biological and Anatomical Characteristics • Hemangioblastoma hemoglobin, hematocrit, erythropoietin • Craniopharyngioma anterior 3rd ventricle to nasopharynx
  39. 39. Clinical Information in CT • Acute, progressive or stationary • Timing important in ischemic disease • previous history of irradiation or operation

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