Introductory Neuroimaging: What you need to know at 3 am And some cool stuff. . .
Outline
Outline
Which study? Acute change
Which study? Vascular
Regarding contrast:
Regarding contrast:
Hounsfield Units (HU)
Outline
Normal Anatomy
Normal Anatomy
Normal Anatomy
Normal Anatomy
Acute Head CT Checklist
Outline
Epidural Hematoma
Acute Subdural Hematoma
Chronic Subdural Hematoma
Isodense Subdural Hematoma
Subarachnoid Hemorrhage
Cerebral Contusion
Subcortical Injury
MRI: Diffuse Axonal Injury
Diffuse Cerebral Edema
Outline
Stroke
Acute Ischemia-Infarction
Diffusion-MRI: Acute Infarct
Acute facial droop, hemiparesis
Angio
Post intervention
Watershed Infarction
Anoxic brain injury
Subacute Infarction
MRI: Enhancing Subacute Infarct
Chronic Infarction
Dural Sinus Thrombosis
Outline
Aneurysmal SAH
Saccular Aneurysm
Fusiform Aneurysm
Active Re-bleeding
Ruptured Aneurysm
Intracerebral Hemorrhage
MRI: Blood Products
MRI: Hemorrhagic Tumor
Parenchymal Hemorrhage with Ventricular Extension
MRI Flow Voids: AVM
8.78M
Category: medicinemedicine

Introductory/ Neuroimaging: What you need to know at 3 am And some cool stuff

1. Introductory Neuroimaging: What you need to know at 3 am And some cool stuff. . .

Kathleen Tozer, MD

2. Outline

• Choosing a study
• Normal anatomy
• Trauma
• Ischemic stroke
• Aneurysm

3. Outline

• Choosing a study
• Normal anatomy
• Trauma
• Ischemic stroke
• Aneurysm

4. Which study? Acute change

• For acute mental status change, first study is
ALWAYS noncontrast head CT
• Brain MR:
– Stroke protocol (noncontrast)
– ICH protocol (with contrast)
– Tumor protocol (with contrast)

5. Which study? Vascular

• CTA:
– Neck: Aortic arch through Circle of Willis.
– Head: Circle of Willis only
• MRA:
– Brain: noncontrast
– Neck: without and with contrast.

6. Regarding contrast:

• Iodinated contrast:
– GFR > 60:
• in the clear
– GFR < 60:
• If acute, tread cautiously, especially if <30
• Hydration, mucomyst, Sodium bicarb protocol
• Decrease dose, Visipaque
– ESRD:
• Coordinate with hemodialysis

7. Regarding contrast:

• Gadolinium contrast:
– GFR > 60:
• in the clear
– GFR 30-60:
• weigh risks.
• Consider noncontrast study first.
• Multihance
– GFR < 30:
• CONTRAINDICATED due to risk of NSF (nephrogenic systemic
fibrosis).
– Try noncontrast.
– Consult radiology for alternative studies.

8. Hounsfield Units (HU)

• CT density scale:







Air = -1000
Fat = -120
Water = 0
Muscle = +40
Blood clot = +65
Bone = +1000
Metal >> +1000

9. Outline

• Choosing a study
• Normal anatomy
• Trauma
• Ischemic stroke
• Aneurysm

10. Normal Anatomy

11. Normal Anatomy

12. Normal Anatomy

13. Normal Anatomy

14. Acute Head CT Checklist


Midline Shift
Mass Effect
Density
CSF Spaces
Vascular Territories
Intra-/Extra-axial
Herniation

15. Outline

• Choosing a study
• Normal anatomy
• Trauma
• Ischemic stroke
• Aneurysm

16.

17. Epidural Hematoma

• Injury to epidural vessel
– Arterial bleeding
• Lentiform shape
• Does not cross sutures
– May cross falx or tentorium
• Look for:
– FRACTURE
– RAPID EXPANSION

18.

19. Acute Subdural Hematoma

• Injury to bridging vessel
– Venous
• Crescent shaped
• May cross sutures
– Does not cross falx or
tentorium
• Does not enter sulci
• Watch for:
– MASS EFFECT
– SLOW EXPANSION

20.

21. Chronic Subdural Hematoma

• HYPODENSE
– (blood degradation)
• MIXED
– (Acute-on-chronic)

22.

23. Isodense Subdural Hematoma

• ISODENSE
– Coagulopathy
– Anemia
– Evolution of blood
products
• Look for:
– Sulcal Effacement
– Subtle Mass Effect

24.

25. Subarachnoid Hemorrhage

• Subarachnoid
– Sulci
– Cisterns
– Ventricles
• Trauma
– lateral convexities
• Aneurysm
– basal cisterns
• Interpeduncular Cistern
– most sensitive

26.

27. Cerebral Contusion

• Intraparenchymal
• “Coup-Contrecoup”
– Blow to head
– Sudden deceleration
– Brain impacts inner table
(contralateral side)
• Look for:
– Scalp contusion
– Halo of edema

28.

29. Subcortical Injury

• Shear-Strain forces
– Penetrating vessels
– Axonal injury
• “Tip of the iceberg”
– Consider MRI
• Neurological deficits may
be out of proportion to
degree of injury visible on
CT

30. MRI: Diffuse Axonal Injury

31.

32.

33. Diffuse Cerebral Edema

• Grey-white interface often
obscured
• Sulcal effacement
• Focal subtypes:
– Vasogenic
• Extracellular
• White matter > GM
– Cytotoxic
• Intracellular
• Grey matter > WM

34. Outline

• Choosing a study
• Normal anatomy
• Trauma
• Ischemic stroke
• Aneurysm

35. Stroke

36.

37. Acute Ischemia-Infarction

• Subtle HYPODENSITY
– Vascular distribution
– Loss of grey-white margin
• CT often NEGATIVE
• Early CT signs
– “Hyperdense MCA”
– “Insular ribbon”
• Role of CT: EXCLUDE
BLEED
• MRA or CTA useful
• DSA for intervention
• Early treatment may
improve outcome

38. Diffusion-MRI: Acute Infarct

39.

40. Acute facial droop, hemiparesis

41.

42.

CTA

43. Angio

44. Post intervention

45. Watershed Infarction

46.

47.

48.

15 hours
later

49. Anoxic brain injury

• Loss of Gray-White
• Progresses with
worsening edema
• PseudoSAH
• Hydrocephalus
• Cisterns
compressed

50. Subacute Infarction


2-14 days out
Hypodensity
ENHANCEMENT
Hemorrhagic
transformation

51. MRI: Enhancing Subacute Infarct

52. Chronic Infarction

• VOLUME LOSS
– Ex vacuo dilatation
• Hypodensity
– encephalomalacia

53. Dural Sinus Thrombosis

• Occlusive thrombosis
• Subtle early signs
– Bilateral infarcts
– Hemorrhages
• CTV or DSA
– Filling defect
• MRI/MRV

54.

55. Outline

• Choosing a study
• Normal anatomy
• Trauma
• Ischemic stroke
• Aneurysm

56.

57. Aneurysmal SAH

• Sudden severe headache
• HYPERDENSE CSF spaces
• Location
– Interhemispheric: ACoA
– Sylvian: MCA
• HYDROCEPHALUS,
VASOSPASM and
ISCHEMIA
– MUST find the aneurysm!
• DSA, CTA and/or MRA

58. Saccular Aneurysm

59. Fusiform Aneurysm

60. Active Re-bleeding

61. Ruptured Aneurysm

62.

63. Intracerebral Hemorrhage

• Hypertension
– Most common
– Characteristic Locations
• IF LOBAR BLEED:
– SEARCH for underlying
cause!
– MRI/MRA/MRV
– DSA or CTA
– Repeat imaging if negative
initially
• Look for:
– EXPANSION
– UNDERLYING LESION

64. MRI: Blood Products

65. MRI: Hemorrhagic Tumor

66.

67. Parenchymal Hemorrhage with Ventricular Extension

68. MRI Flow Voids: AVM

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