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Ct brain presentation

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easy interpretation of ct brain for medicine and neurology residents

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Ct brain presentation

  1. 1. CT BRAIN for Medical and Neurology residents Qamar zaman FCPS,SCE(NEUROLOGY)
  2. 2. Terminology used in CT. • Section of the study (most commonly axial is used). • Right and left side of the image. • Density of a structure is taken relative to the density of water and described as isodense, hyperdense and hypodense. • Location and anatomical structures involved. • Should be able to formulate radiological differentials.
  3. 3. Which one is CT brain
  4. 4. How to differentiate CT from MRI • Bone is dense(white) on CT brain while hypo intense(dark) on MRI(outer bright signals on MRI are due to subcutaneous fats). • Grey-white matter differentiation is clear on MRI compared to the CT. • Presence of periventricular lucent areas in MRI. • MRI usually have multiple films compared to commonly single in CT
  5. 5. CT machine
  6. 6. Mechanism • X-ray emitter and detector rotate in circular fashion. • When radiation pass through exposed structure they behave differently depending on the density and physical properties. • A visual representation of the raw data obtained is called a sinogram which is raw form. • The data must be processed using a form of tomographic reconstruction which produces a series of cross-sectional images.
  7. 7. Image acquisition • Unit used to measure the density are called as Hounsfield. • It can range on a scale from +3071 (most attenuating) to −1024 (least attenuating) on the Hounsfield scale.
  8. 8. Tissue densities on CT
  9. 9. • Contrast used for X-ray CT, as well as for plain film X-ray, are called radiocontrasts. Radiocontrasts for X-ray CT are, in general, iodine-based. Often, images are taken both with and without radiocontrast
  10. 10. Precautions • If you are pregnant or suspect that you may be pregnant, you should notify your doctor. Radiation exposure during pregnancy may lead to birth defects • Nursing mothers may want to wait 24 hours after contrast material is injected before resuming breastfeeding. • there is a risk for allergic reaction to the dye
  11. 11. • Patients with kidney failure or other kidney problems should notify their doctor. • patients taking the diabetes medication metformin (Glucophage) should alert their doctors before having IV contrast as it may cause a rare condition called metabolic acidosis.
  12. 12. When to prefer CT over MRI • Trauma or acute emergency settings where time is important. • When ruling out bony injuries and bleeds that are easily picked. • Contraindications to MRI eg metallic objects. • Claustrophobic patients. • Cost and availibilty factors.
  13. 13. Various sections
  14. 14. Axial section
  15. 15. saggital
  16. 16. coronal
  17. 17. Modalities of CT used in brain • Plain non contrast CT (with parenchymal and bone windows). • CT with contrast. • CT perfusion. • CT Angiogram. • CT Venogram. • CT with special cuts like orbit, Pituatrity fossa.
  18. 18. Anatomical Land marks. • Cortex and division into various lobes. • Subcortical structures including basal ganglia,thalamus . • Pituatry area and cavernous sinus region. • Brainstem. • CSF system. • Arterial and venous system.
  19. 19. Central Sulcus
  20. 20. Brain lobes
  21. 21. Fig 2a: T1 MRI axial projection. 1: inter- hemispheric scissure; 2: lateral sulcus; 3: frontal lobe; 4: insula lobe; 5: temporal lobe; 6: occipital lobe.
  22. 22. Antero-medial temporal lobes
  23. 23. Pituitary area
  24. 24. Dural sinuses
  25. 25. Sigmiod sinus
  26. 26. Transverse sinus
  27. 27. Straight sinus
  28. 28. Deep cerebral veins
  29. 29. Superior saggital sinus
  30. 30. orientation • Two-dimensional CT images are conventionally rendered so that the view is as though looking up at it from the patient's feet. • Hence, the left side of the image is to the patient's right and vice versa, while anterior in the image also is the patient's anterior and vice versa.
  31. 31. Approach to CT • Check name ,identification and date of study, orientation. • Start from upper most or lower most cuts. • Look from outside to inside or inside to outside. • Look for bones, sinuses,orbits. • Extradural, subdural and meningeal details and enhancement if contrast film.
  32. 32. Approach to the CT • Look parenchyma for hypodensities ,hyperdensities, their location, shape, homogenous/heterogenous,any mass effect or odema. • Grey-white matter differentiation, any enhacement if contrast film. • Ventricles symmetry and cisterns any effacement.
  33. 33. Density of various structures
  34. 34. Hyperdensities • Blood. • Clot • Calcium. • Prosthesis. • Contrast uptake. • Choriod plexsus calcification and bone are the do main hyperdensities that are present in normal CT.
  35. 35. Hypodense • Most commonly odema secondary to: • Infection • Inflamation. • Stroke. • Mass lesion. • Fat containing structures. • Air • Paranasal sinuses and mastiod are structures that are hypodense in normal cases.
  36. 36. Approach to the CT • Explain the findings in systematic manner. • Mention the Shape, size, density, location and extent and any mass effects related to the findings. • Compare to the other side if applicable. • Any contrast uptake. • Formulate major or likely differentials related to observed findings. • What further imaging or test may be helpful to clear likely diagnosis.
  37. 37. Causes of air • Air filled spaces. • Base of the skull fracture. • Craniotomy or after other surgeries
  38. 38. Disorders of Sinuses • Acute bacterial sinusistis. • Chronic purulent sinusitis. • Fungal infection. • Mucocoele. • Tumors.
  39. 39. Maxillary sinus
  40. 40. Maxillary sinus disease
  41. 41. Spheniod Mucocoele
  42. 42. Maxillary,ethmiod and spheniod disease
  43. 43. Frontal sinus disease
  44. 44. Sinus tumor with widespread intracranial extension
  45. 45. Sinus disease with orbital extension
  46. 46. Left Mastiod disease
  47. 47. Rt mastiod disease
  48. 48. Right Mastioditis
  49. 49. Grey and white matter differentiation • Normally Grey matter is outer denser structure and white matter in inner hypodenser. • Grey matter contains neurons cell bodies while white matter contain axons with rich fatty myelin sheath making it hypodense. • This differentiation is loss in case of cerebral odema.
  50. 50. Normal Grey white matter
  51. 51. Causes of cerebral odema • Infection. • Mass lesion. • Stroke. • Metabolic causes.
  52. 52. • In true isolated cytotoxic oedema little change is evident on CT as a mere redistribution of water from extracellular to intracellular compartments does not result in attenuation changes. The changes colloquially ascribed to 'cytotoxic oedema' are in fact mostly due to ionic oedema, and are described separately. This is why brain CT is often normal in patients with an acute ischaemic stroke.
  53. 53. Cytotoxic
  54. 54. • grey-white matter differentiation is maintained and the oedema involves mainly white matter, extending in finger-like fashion • secondary effects of vasogenic oedema are similar to cytotoxic oedema, with effacement of cerebral sulci, with or without midline shift
  55. 55. Vasogenic
  56. 56. Interstitial odema
  57. 57. Disoders of CSF spaces • Hydrocephalus communicating and non communicating including IIH,NPH. • Loss of csf spaces usually secondary to degenerative and other secondary processes.
  58. 58. CNS herniations • There are a number of different patterns of cerebral herniation which describe the type of herniation occurring: • subfalcine herniation • transalar herniation: ascending and descending • transtentorial herniation – downward: uncal herniation – upward: ascending transtentorial herniation* • tonsillar herniation* • extracranial herniation
  59. 59. Subfalcine herniation
  60. 60. Uncal herniation
  61. 61. Foraminal herniation
  62. 62. Extracranial herniation
  63. 63. Midline shift
  64. 64. Trauma • Soft tissue injuries. • Skull fractures. • Extradural,subdural and subarachniod hemorrhage. • Contusions and diffuse axonal injury with associated cerebral odema.
  65. 65. Skull fracture with extradural hematoma
  66. 66. Skull fracture
  67. 67. Basilar fracture
  68. 68. Skull base fracture with pneumocephalus
  69. 69. Hemorrhagic contusions
  70. 70. Diffuse axonal injury
  71. 71. EDH
  72. 72. SDH
  73. 73. Chronic SDH
  74. 74. Traumatic SAH
  75. 75. Vascular Insults • Subarachniod Hemorrhage. • Lobar and basal ganglia bleeds. • Ischemic strokes. • Venous infarcts. • Disections
  76. 76. Aneurysmal SAH
  77. 77. SAH
  78. 78. Putamen bleed
  79. 79. Pontine bleed
  80. 80. Intraventricular bleed
  81. 81. RT MCA infarct
  82. 82. RT MCA infarct
  83. 83. Dense MCA sign
  84. 84. Left Subcortical infarct
  85. 85. ACA
  86. 86. ACA
  87. 87. Cerebellar infarct with hemorrhagic conversion
  88. 88. PCA
  89. 89. PCA
  90. 90. Venous infarct
  91. 91. Venous infarct
  92. 92. Infections • Meningial enhancement and thickness, extradural and subdural collection, with associated communicating hydroceph. • Focal parenchymal injury and abscess, mass lesions with mass affects. • Ventriculitis and diffuse cerebral odema.
  93. 93. • Tumors and masses. • Congenital abnormalities. • Toxic metabolic insults. • Disections and aneurysms. • Hypoxic injury. • States where CT is useless.

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