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CT BRAIN - BASICS

CT BRAIN - BASICS. Dr Mohamed el Safwany , MD. Intended learning outcome. The student should learn at the end of this lecture CT brain basics. CT Principle. RING OF XRAY DETECTORS. Frankfurt plan e. HOUNSFIELD UNITS. Numeric information in each pixel of ct image

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CT BRAIN - BASICS

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  1. CT BRAIN - BASICS Dr Mohamed el Safwany, MD.

  2. Intended learning outcome The student should learn at the end of this lecture CT brain basics.

  3. CT Principle RING OF XRAY DETECTORS

  4. Frankfurt plane

  5. HOUNSFIELD UNITS • Numeric information in each pixel of ct image • Related to composition & nature of tissue • Represent the density of tissue • Also called as CT NUMBER

  6. CT /MRI • CT PICTURE • WHITE MATTER IS DARKER THAN GREY MATTER SINCE LIPID CONTAINING MATERIAL IS RADIOLUCENT • CSF IS BLACK • MR PICTURE

  7. Step wise approach • Ventricles/ cisterns • Cortex • Deep gray matter • Focal lesions • Bone • Extracranial soft tissue • Para nasal sinuses

  8. LV FRONTAL HORN 3V OCCIPITAL HORN FORAMEN OF MONRO trigone TEMBORAL HORN 4 V AQUEDUCT OF SYLVIUS

  9. COMMON SECTIONS

  10. ABOVE THE LEVEL OF FORAMEN MAGNUM VA MEDULLA 4 V TONSIL INT OCC PROT

  11. LEVEL OF FOURTH VENTRICLE Optic nerve CPCISTERN TEM HORN PONS 4V MCP

  12. LEVEL ABOVE FOURTH VENTRICLE OLF SULCUS SYLV FISSURE SUPRA SELLAR CISTERN AMB CIST MB 4V vermis

  13. THIRD VENTRICULAR LEVEL

  14. LOW VENTRICULAR

  15. Above ventricle level

  16. Cerebral Arterial Territory • MCA-most of lateral hemisphere, Basal ganglia, insula, • ACA-Inferomedial basal ganglia,ventromedial frontal lobes, anterior 2/3rd medial cerebral hemispheres, 1 cm supero medial brain convexity • PCA-Thalami, midbrain, posterior 1/3of medial hemisphere, occipital lobe, postero medial temporal lobe

  17. ACA MCA PCA

  18. AICA-inferolateral part of pons, middle cerebellar peduncle, floccular region, anterior petrosal surface of cerebellar hemisphere • PICA-posteroinferior surface of cerebellar hemisphere , ipsilateral part of inferior vermis, • Superior cerebellar artery-superior aspect of cerebellar hemisphere (tentorial surface), ipsilateral superior vermis, largest part of deep white matter including dentate nucleus, pons

  19. Water shed infarct

  20. CEREBRAL ISCHEMIA

  21. Cerebral ischemia • Significantly diminished blood supply to all parts(global ischemia) or selected areas(regional or focal ischemia) of the brain • Focal ischemia- cerebral infarction • Global ischemia-hypoxic ischemic encephalopathy(HIE),hypotensive cerebral infarction

  22. Goal of imaging • Excludehemorrhage • Identify the presence of an underlying structural lesion such as tumour , vascular malformation ,subdual hematoma that can mimic stroke • Identify stenosis or occlusion of major extra- and intracranial arteries • Differentiate between irreversibly affected brain tissue and reversibly impaired tissue (dead tissue versus tissue at risk)

  23. Infarct vspneumbra • In the central core of the infarct, the severity of hypoperfusion results in irreversible cellular damage . • Around this core, there is a region of decreased flow in which either: • The critical flow threshold for cell death has not reached • Or the duration of ischemia has been insufficient to cause irreversible damage.

  24. Hyper acute infarct(<12 hours) • Acute infarct(12 - 48 hours) • Subacute infarct(2 - 14 days) • Chronic infarct(>2 weeks) • Old infarct(>2 months)

  25. CT-Hyperacute infarct • Hyperdense MCA sign-acute intraluminal thrombus • Attenuation of lentiform nulei • Dot sign-occluded MCA branch in sylvian fissure • Insular ribbon sign –grey white interface loss along the lateral insula

  26. Dense mca sign

  27. ‘ loss of insular ribbon’

  28. M C A DOT SIGN

  29. ATTENUATION OF LENTICULAR NUCLEUS

  30. CT- Acute infarct • Low density basal ganglia • Sulcal effacement • Wedge shaphed parenchymal hypo density area that involves both grey and white matter • Increasing mass effect • Hemorrhagic transformation may occur -15 to 45% ( basal ganglia and cortex common site) in 24 to 48 hours

  31. CT-chronic infarct • Plain ct • Focal, well-delineated low-attenuation areas in affected vascular distribution • sulci become prominent; ipsilateral ventricle enlarges • Dystrophic Ca++ may occur in infarcted brain but is very rare • CECT: No enhancement

  32. INFARCT / TUMOUR • CLINICAL HISTROY • DISTRIBUTION • SHAPES • GRAY / WHITE INVOLVEMENT • ADVANCED IMAGING

  33. VENOUS INFARCT • HISTROY • BEYOND VASCULAR DISTRIBUTION • HAEMORRHAGIC INFARCT • THORMBUS IN VENOUS SINUSES • SYMMETRICAL LOW ATTENUATION IN DEEP GRAY MATTER - DEEP CEREBRAL VEIN THORMBUS

  34. EDEMA/ INFARCT • INFARCT TYPICAL VASCULAR DISTRIBUTION GRAY MATTER INVOLVEMENT • EDEMA NOT CONFINED TO VASCULAR DISTRIBUTION MOSTLY INVOLVES WHITE MATTER

  35. PCA INFARCT

  36. MCA INFARCT

  37. ACA INFARCT

  38. WATERSHED INFARCT

  39. Old infarct

  40. H’gic infarct

  41. Text Book David Sutton’s Radiology Clark’s Radiographic positioning and techniques

  42. Assignment Two students will be selected for assignment.

  43. Question Describe CT of acute brain infarction?

  44. Thank u

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