Basic Interpretation of CT Scan. Hon-Man Liu 廖漢文

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1 Basic Interpretation of CT Scan Hon-Man Liu 廖漢文

2 Basic Interpretation of CT Scans Most of the CT pictures are nonspecific CT pictures are depending on the density of the structures.

3 Principles of CT Diagnosis Pre-contrast study Post-contrast study Change in adjacent structures Clinical Information Biological or anatomical characteristics

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 Hypo-density in CT Higher than CSF but lower than brain tissue tumor, abscess, resolving hematoma, evolution infarct, protein, blood, debris

6 Hypo-density in CT Higher than CSF but lower than brain tissue

7 Hypo-density in CT Iso-density to CSF chronic hematoma, chronic infarct, porencephaly, congenital cyst, encephalomalacia change Water-like content

8 Hypo-density in CT Iso-density to CSF

9 Hypo-density in CT fat or cholesterol air myxoid Lower than CSF congenital tumor: dermoid, epidermoid,lipoma, head injury, pneumocephaly

10 Hypo-density in CT Lower than CSF

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 Hyper-density in CT Iso-or higher than bone

13 Hyper-density in CT Less than bone but higher than brain tissue

14 Post-contrast CT Enhancement patterns gyral, ribbon, cortical soild rim or ring mural nodular linear and dot heterogenous no enhancement

16 Enhancement Patterns

17 Change in Adjacent Structures in CT Edema Bone Ventricles, sulci and cistern

18 Edema Pattern in CT Vasogenicedema tumors, infection, late infarct along the white matters, finger-like Interstitial edema periventricular white matter, ependymitis granularis Cytotoxicedema ischemia or infarct, gray matter

19 VasogenicEdema

20 Vasogenicedema

21 CytotoxicEdema

22 CAUSES of RAISED INTRACRANIAL PRESSURE Hydrocephalus Brain edema S.T.L Tumor, Hematoma, Cyts, Infarct.

23 RAISED INTRACRANIAL PRESSURE DEATH ICP DAYS WEEKS HOURS Focal mass effect CSF space change hydrocephalus Herniation Coning

24 Herniation Subfalcine Parahippocampus Central, tonsillar

25 SUBFALCINE HERNIA

26 TRANSTENTORIAL HERNIAS 1. PARAHIPPOCAMPAL GYRUS (PHG) HERNIATION 2. CENTRAL/DIENCEPHALIC HERNIATION MAY OCCUR INDEPENDENTLY OR IN COMBINATION

27 PARAHIPPOCAMPAL GYRUS (PHG) HERNIATION

28 COMPLICATIONS of PHG HERNIATION

29 COMPLICATIONS of PHG HERNIATION PCA ossculsion 3rd nerve palsy

30 CENTRAL HERNIATION MAMILLARY BODY PONS

31 CENTRAL HERNIATION NORMAL HERNIA AP diameter > trans diameter AP diameter =/< trans diameter

32 SECONDARY BRAIN STEM HAEMORRHAGES Duret hemorrahge

33 CEREBELLAR TONSILAR HERNAITION OR CONING

34 Bone Change in CT Foramen internal auditory canal, foramen ovale, orbital fissures Cranium bone hyperostosis

35 CSF Spaces Change in CT Widening or obliterated Sensitive to mass effect Proportional or in-proportional

36 CT of Cerebral Ischemia (lentiformnucleus sign) Ischemia: gray matter increased water --density -- density closed to white matter --loss of the differentiation between the lentiform nucleus and internal capsule

37 CT of Cerebral Ischemia (Insular ribbon sign) Ischemia -- cytotoxic edema -- cellular swelling -- mass effect --straightening the normal waving insular ribbon

38 CT of Cerebral Ischemia (Hyper-dense vascular sign) Ischemia --blood stasis in great vessel such as M1 - -blood clot --high density

39 Biological and Anatomical Characteristics Hemangioblastoma hemoglobin, hematocrit, erythropoietin Craniopharyngioma anterior 3rd ventricle to nasopharynx

40 Clinical Information in CT Acute, progressive or stationary Timing important in ischemic disease previous history of irradiation or operation

PE finding: Left side extremities mild weakness No traumatic wound No bloody otorrhea, nor rhinorrhea

PE finding: Left side extremities mild weakness No traumatic wound No bloody otorrhea, nor rhinorrhea Case report A 82-year-old man was suffered from sudden onset spasm of extremities then he fell down to the ground with loss of consciousness. He recovered his consciousness 7-8 mins later but his conscious