Head CT Basics - Lowther.pdf ct scan basic
- 1. INTRODUCTION TO CT HEAD FOR THE ADVANCED PRACTICE PROVIDER Ervin Lowther, MD Medical Director of Neuroradiology Prisma Health - Upstate
- 5. Can’t miss 4 H’s on a head CT • ? • ? • ? • ?
- 6. Name 3 CT Signs of Early Infarction • ? • ? • ?
- 7. 4 Types Intracranial Hemorrhage
- 8. Outline • CT concepts – Density • Concepts in brain imaging – Gray-white differentiation – Types of cerebral edema – Sulci
- 11. CT Attenuation – Density of tissue Gray scale • air black • fat darker gray • CSF gray • brain lighter gray • acute blood, contrast white • bone very white
- 12. CT HU In The Brain • HU of grey matter (GM) and (WM) – GM ~ 40 – WM ~ 30 • HU of hemorrhage – Hyperacute ~ Hct – Acute ~60-80 – Subacute ~ 40 – Chronic ~ 0-20
- 22. Important CT concepts in Brain Imaging • Attenuation • Gray-white differentiation • Types of cerebral edema – Determine stroke versus stroke mimic • Sulci
- 26. Types of Cerebral Edema Cytotoxic • Brain cells die • Influx of water into GM • Lose GM-WM differentiation Vasogenic • Something irritates the brain • Influx of water in WM • Accentuates GM-WM differentiation GM is the key!
- 27. Types of Cerebral Edema Cytotoxic Vasogenic WM Edema Edema WM GM WM WM Edema WM
- 28. Causes of Cerebral Edema Cytotoxic • Anything that causes the cells to die • Infarcts/Ischemia • Necrotizing infection Vasogenic • Anything that disrupts the blood brain barrier • Neoplasm • Infection • Tumefactive demyelination
- 31. Stroke • Death of brain cells due to lack of oxygen – Caused by blockage of blood flow or rupture of a blood vessel • Stroke is a clinical diagnosis • We see infarcts on imaging
- 32. CT Signs of Infarction • 3 early signs of infarction – Loss of grey-white matter differentiation • Loss of insular ribbon – Sulcal effacement – Hyperdense vessel sign
- 33. Baseline CT < 3 hrs Case
- 34. Day 3 CT s/p t-PA Case
- 35. Identify Vascular Territory • Must identify vascular distribution – Middle cerebral artery (MCA) – Posterior cerebral artery (PCA) – Anterior cerebral artery (ACA) – Basilar artery (BA) – Cerebellar arteries • Superior cerebellar artery (SCA) • Anterior inferior cerebellar artery (AICA) • Posterior inferior cerebellar artery (PICA)
- 37. Bilateral ACA Infarcts And Cerebral Edema
- 38. Day 3 CT s/p TPA MCA infarct with hemorrhage
- 39. diffuse anoxic injury How ‘bout this one?
- 40. Can’t Miss 4 H’s • Hemorrhage • Hydrocephalus • Herpes • Herniation
- 41. Intracranial Hemorrhage • Intraparenchymal • Subarachnoid • Subdural • Epidural • Intraventricular
- 42. Hypertensive Hemorrhage • Most common sites – Basal ganglia • Most common site – Thalamus – Brainstem (pons) – Cerebellum
- 43. HTN Bleed
- 45. Subarachnoid Hemorrhage • Within the subarachnoid spaces – Cisterns – Fissures – Sulci • Most common cause of SAH? – Trauma
- 47. Acute SAH
- 48. Subdural Hemorrhage • Between the dura and arachnoid • Crescentic • Can cross suture lines – Cannot cross the midline • Superior sagittal sinus • Not necessarily associated with a frx – But you’d better still look
- 50. What about this one?
- 51. Epidural Hemorrhage • Between the skull and dura • Lenticular • Does not cross the sutures – Dura is tightly adherent at sutures • Highly associated with a fracture
- 55. HEMORRHAGE IPH SAH SDH EDH
- 57. Which One of the 4 H’s?
- 58. Hydrocephalus • Enlargement of the ventricles due to alteration of CSF flow • Communicating or non-communicating (obstructive) • Look for enlargement of the temporal horns and rounding of the third ventricle!
- 62. Infarct or One of the 4 H’s?
- 64. Infarct or One of the 4 H’s?
- 65. Infarct or One of the 4 H’s? Herpes encephalitis
- 66. Herpes Encephalitis • HSV causes necrotizing encephalitis – Usu HSV-1 • Limbic system – Temporal lobes, insula, hippocampus, subfrontal area, cingulate gyrus • Can be symmetric or asymmetric • Can be hemorrhagic – Necrotizing hemorrhagic encephalitis
- 67. Herniation • Many different types but most commonly – Uncal – Subfalcine – Tonsillar – Transtentorial
- 69. 1. Inferior displacement of sylvian fissure 2. Subfalcine herniation 3. Entrapment of lateral ventricle 4. Compression of ACA 5. Midbrain contusion 6. Duret (midbrain) hemorrhage 7. Descending transtentorial herniation 8. Compression of PCA 9. Widening of ipsilateral CPA 10. Descending tonsillar herniation CEREBRAL HERNIATIONS
- 70. Uncal Herniation Subfalcine Herniation
- 71. Wrap It Up!
- 72. HEMORRHAGE IPH SAH SDH EDH
- 73. Can’t Miss 4 H’s • Hemorrhage • Hydrocephalus • Herpes • Herniation
- 74. Name 3 CT Signs of Early Infarction • Loss of gray-white differentiation • Sulcal effacement • Hyperdense vessel sign
- 75. Take Home Points • Stroke remains a clinical diagnosis • Best initial test = noncontrast head CT • GM is the key to differentiating types of edema
- 76. Take Home Points • Look at insular ribbon for early MCA infarcts • Look at temporal horns for early hydro • Check the interpeduncular fossa for SAH