Ct scan interpretation
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Ct scan interpretation

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Ct scan interpretation Ct scan interpretation Presentation Transcript

  • Basic Interpretation of CT Scan Hon-Man Liu 廖漢文
  • Basic Interpretation of CT Scans Most of the CT pictures are non- specific CT pictures are depending on the density of the structures.
  • Principles of CT Diagnosis • Pre-contrast study • Post-contrast study • Change in adjacent structures • Clinical Information • Biological or anatomical characteristics
  • 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
  • Hypo-density in CT Higher than CSF but lower than brain tissue tumor, abscess, resolving hematoma, evolution infarct, protein, blood, debris
  • Hypo-density in CT Higher than CSF but lower than brain tissue
  • Hypo-density in CT Iso-density to CSF chronic hematoma, chronic infarct, porencephaly, congenital cyst, encephalomalacia change Water-like content
  • Hypo-density in CT Iso-density to CSF
  • Hypo-density in CT Lower than CSF • fat or cholesterol congenital tumor: dermoid , epidermoid,lipoma, • air head injury, pneumocephaly • myxoid
  • Hypo-density in CT Lower than CSF
  • 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
  • Hyper-density in CT Iso- or higher than bone
  • Hyper-density in CT Less than bone but higher than brain tissue
  • Post-contrast CT Enhancement patterns • gyral, ribbon, cortical • soild • rim or ring • mural nodular • linear and dot • heterogenous • no enhancement
  • Enhancement Patterns
  • Change in Adjacent Structures in CT • Edema • Bone • Ventricles, sulci and cistern
  • 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
  • Vasogenic Edema
  • Vasogenic edema
  • Cytotoxic Edema
  • CAUSES of RAISEDCAUSES of RAISED INTRACRANIAL PRESSUREINTRACRANIAL PRESSURE HydrocephalusHydrocephalus BrainBrain edemaedema S.T.LS.T.L TumorTumor,, HematomaHematoma,, CytsCyts,, InfarctInfarct……..
  • RAISED INTRACRANIALRAISED INTRACRANIAL PRESSUREPRESSURE ICPICP DAYSDAYS WEEKSWEEKS HOURSHOURS ConingConing Focal mass effectFocal mass effect CSF spaceCSF space changechange hydrocephalushydrocephalus HerniationHerniation DEATHDEATH
  • HerniationHerniation Subfalcine Parahippocampus Central, tonsillar
  • SUBFALCINE HERNIASUBFALCINE HERNIA
  • TRANSTENTORIAL HERNIASTRANSTENTORIAL HERNIAS 1. PARAHIPPOCAMPAL GYRUS (PHG) HERNIATION 2. CENTRAL/DIENCEPHALIC HERNIATION MAY OCCUR INDEPENDENTLY ORMAY OCCUR INDEPENDENTLY OR IN COMBINATIONIN COMBINATION
  • PARAHIPPOCAMPAL GYRUSPARAHIPPOCAMPAL GYRUS (PHG) HERNIATION(PHG) HERNIATION
  • COMPLICATIONS of PHGCOMPLICATIONS of PHG HERNIATIONHERNIATION
  • COMPLICATIONS of PHGCOMPLICATIONS of PHG HERNIATIONHERNIATION PCA ossculsion 3rd nerve palsy
  • CENTRAL HERNIATIONCENTRAL HERNIATION MAMILLARYMAMILLARY BODYBODY PONSPONS
  • CENTRAL HERNIATIONCENTRAL HERNIATION NORMALNORMAL HERNIAHERNIA AP diameter > trans diameter AP diameter =/< trans diameter
  • SECONDARY BRAINSECONDARY BRAIN STEMSTEM HAEMORRHAGESHAEMORRHAGES Duret hemorrahge
  • CEREBELLAR TONSILAR HERNAITIONCEREBELLAR TONSILAR HERNAITION CONINGCONING OROR
  • Bone Change in CT • Foramen internal auditory canal, foramen ovale, orbital fissures • Cranium bone hyperostosis
  • CSF Spaces Change in CT • Widening or obliterated • Sensitive to mass effect • Proportional or in-proportional
  • • 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)
  • CT of Cerebral Ischemia (Insular ribbon sign) Ischemia -- cytotoxic edema -- cellular swelling -- mass effect -- straightening the normal waving insular ribbon
  • CT of Cerebral Ischemia (Hyper-dense vascular sign) • Ischemia -- blood stasis in great vessel such as M1 - - blood clot -- high density
  • Biological and Anatomical Characteristics • Hemangioblastoma hemoglobin, hematocrit, erythropoietin • Craniopharyngioma anterior 3rd ventricle to nasopharynx
  • Clinical Information in CT • Acute, progressive or stationary • Timing important in ischemic disease • previous history of irradiation or operation