Neuroradiology Flashcards

1
Q

Computed Tomography

A

–Ionizing radiation (x-rays)

–Measuresattenuation of radiation by tissues

–Revolutionized the practice of modern medicine

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2
Q

What are the risk of a CT scan?

A
  • Cancer induction
  • Contrast nephropathy
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3
Q

What are the color densities of CT scan?

A

–CSF

•Dark

–Grey matter

•Light grey

–White matter

•Dark grey

–Bone (Skull)

Bright (white)

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4
Q

Density of blood depends on age. What is the difference between acute bleed and chronic bleed?

A

Acute Bleed - Bright

Chronic - Dark

Epidural hematoma: acute bleed (Left picture)

Subdural hematoma: Chronic bleed (right picture)

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5
Q

Intravenous Contrast is used for CT scans. It is Iodinated, causes high attenuation of x-rays. How does it appear?

A

Appears bright

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6
Q

What Intravenous Contrast not used for?

A

Not used for head trauma

  • Acute hemorrhage and contrast both appear bright
  • Want to avoid confusing one for the other
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7
Q

What is Intravenous Contrast helpful for?

A

Intracranial infection or tumor

  • Inflammation from infection and tumor disrupts the blood-brain barrier
  • Contrastenters into diseased areas of brain and causes them to become brighter and easier to detect
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8
Q

What is the difference between these two images?

Images of Abscess

A

Left image = Without contrast

Right image - With contrast

CT scan

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9
Q

This is an image of?

A

Glioblastoma Multiforme

CT scan w/ contrast

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10
Q

Magnetic Resonance Imaging

A

–Uses large magnetic field

–No known increased cancer risk

–Complex physics; measures radiofrequency signal from protons

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11
Q

What are the imaging sequences of an MRI?

A

–T1weighted

•Fatis bright, water is dark (fat has lots of H1)

–T2weighted

•Wateris bright (think H2O)

–Diffusion weighted imaging (DWI)

•Acute stroke is bright

–Susceptibility weighted imaging (SWI)

•Blood is very dark

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12
Q

What are the strengths of T1 compared T2?

A

–T1weighted

  • Anatomy
  • Bone marrowpathology (such as tumor)

–T2 weighted

  • Pathology
  • Edema (increased water content) - bright

Infection, tumor, inflammation (good for detecting this)

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13
Q

Which image was done with T1 weighed and which one is done with T2 weighed?

A

Left image = T1 (Cerebrospinal fluid is dark)

Right image = T2 (Cerbrospinal fluid is bright)

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14
Q

What type of MRI was this image obtained from?

A

T1

Bright fatty bone marrow of the skull

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15
Q

How does blood appear on MRI?

A

– Appearance depends on ageand composition of blood products

–SWI sequence

•Very dark in most stages of blood

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16
Q

IV contrast w/ MRI

A

•Intravenous contrast

–Gadolinium; large radiofrequency signals

–Appears very bright

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17
Q

Using IV contrast w/ MRI is helpful for?

A

–intracranial infection or tumor

  • Inflammation from infection and tumor disrupts the blood-brain barrier
  • Contrastenters into diseased areas of brain and causes them to become brighter and easier to detect
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18
Q

This radiographic test was used to obtain this image?

A

MRI w/ contrast

Image of Abscess

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19
Q

This is an image of ?

A

Glioblastoma Multiforme

Done with MRI w/ contrast

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20
Q

CT vs MRI

Which is which?

A

LEft

CT: Bone bright, scalp fat dark

Right

MRI: Bone bright + dark, scalp fat bright

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21
Q

What are the two different type of stroke a person could have?

A

•Hemorrhagic stroke

–Bleeding in the brain

–Usually due to hypertension

•Ischemic stroke

–Lack of blood flow to the brain

–Usually due to clot

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22
Q

Acute Ischemic Stroke

Timing?

Physiology?

A

•Timing

–Less than 2 weeks old (including acute and subacutestages)

•Physiology

–Cytotoxic edema

•Increased intracellular fluid

Decreased extracellular fluid

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23
Q

On CT scan, How does Acute Ischemic Stroke appear?

A

–Increased water in brain tissue

–Affected tissue becomes darker with time

–Very early stroke is difficult to detect

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24
Q

If 6 past after an Acute Ischemic Stroke, how does that affect the CT scan?

A

– At 6 hours, 60% of patients will have CT abnormality

–At 24 hours, all patient will have CT abnormality

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25
Q

Image of CT scan

Acute Left middle Cerebral Artery territory Ischemic Stroke

A
26
Q

Image of CT scan

Acute Brainstem Ischemic Stroke

A
27
Q

How does an Acute Ischemic Stroke appear on MRI? and what technique is used?

A

•Diffusion weighted imaging (DWI)

–Acute ischemic stroke is bright

28
Q

What radiological testing is excellent for detecting very early ischemic strokes?

A

Diffusion weighted imaging (DWI)

Catches stroke between 10-60 min

29
Q

Image of DWI Sequence

Left Image: Acute Right Cerebellar Ischemic Stroke

Right Image: Acute left middle cerebral artery ischemic stroke

A
30
Q

What causes the bright signal in a diffucion weighed image?

A
  • Brain cells swell, taking in extracellular water
  • Restricted motion of free water outside cells causes the bright signal
31
Q

This is an image of a Acute Ischemic Stroke done by T2 sequence MRI. WHat is the radiological test detecting?

A

It detects increased water in the brain, which appears as a bright signal.

32
Q

How long does it take for increased water in brain tissue to appear after an ischemic stroke?

A

3 hours

(image of Acute Stroke MRI T2)

33
Q

What is a Hemorrhagic transformation?

A

–Usually occurs 2-5 days after ischemic stroke onset

–Related to reperfusion of infarcted brain

–Occasionally spontaneous

34
Q

Treatment with thrombolytic drugs is the most common cause of what?

A

Hemorrhagic transformation

35
Q

Image of Hemorrhagic Transformation

A

Left image: Acute left middle cerebral artery territory stroke

Right image: Acute hemorrhage in infarcted tissue

36
Q

Chronic Ischemic Stroke

Timing?

Physiology?

A

•Timing

–Greater than 2 weeks old

•Physiology

–Edema resolved

-Dead tissue is removed and is replaced by fluid

37
Q

How does a Chronic Ischemic Stroke appear on CT scan compaired to MRI?

A

CT: it is very dark (near water) density

MRI: Very bright (near water) signal of T2 sequence

38
Q

These are images of Chronic Ischemic Strokes (Left image = Old right middle cerebral artery stroke and Right= Old right basal ganglia stroke). What imaging test was used?

A

Note that the fluid is dark

CT scan

39
Q

This is an image of a Chronic Stroke (Left = Old left occipital stroke and right= Old left middle cerebral artery stroke). What imaging study was used?

A

MRI (T2)

40
Q

Image of Stroke Territories

A
41
Q

These are images of what type of test?

A

CT angiogram on the left and CT Venogram on the right

42
Q

What is occuring in these images and what test is being used?

A

Left image: Noncontrast CT sca

Bright clot in left middle cerebral artery

CT angiogram

Left middle cerebral artery occlusion

43
Q

What is occuring in these images and what test are being used?

A

Left: CT angiogram

Left middle cerebral artery occlusion

Right: DWI (bright signal)

left middle cerebral artery territory

44
Q

What is occuring in these images and what test are being used?

A

Left: CT scan

Acute Left middle cerebral artery territory stroke

Right Cerebral Blood Flow map (CT perfusion imaging)

Decreased flow to left middle cerebral artery territory

45
Q

What is occuring in these images and what test are being used?

A

Left: CT angiogram

Occlusion of basilar artery

Right: CT scan

Acute brainstem stroke

46
Q

This is an image of what type of test?

A

MR Angiogram

47
Q

What type of damge occured in this image?

A

Left middle cerebral artery occlusion

48
Q

What are the two types of Hydrocephalus

A

Communicating and Non-communicating

49
Q

What is Communicating Hydrocephalus?

A

–All ventricles enlarged

–Usually caused by hemorrhage or infection

50
Q

Whats is non-communicating hydrocephalus?

A

–Not all ventricles enlarged

–Structural CSF flow obstruction

–Causes include brain mass or developmental anomaly

51
Q

The right image is a picture of a normal head. What is occuring in the left image? What test was used to capture this image?

A

Communicating Hydrocephalus

MRI: Sagittal T1

Decreased CSF absorption by arachnoid granulations – blood from subarachnoid hemorrhage, or meningitis scarring)

Normal pressure hydrocephalus – wet, wobbly, and wacky.

52
Q

This is an image of what?

A

Communicating Hyrdocephalus

MRI: Axial T1

Looks like a Rosarch Test

53
Q

This is an image of what?

A

Communicating Hydrocephalus

MRI: Axial T2

54
Q

This is an image of?

A

Non-communicating Hydrocephalus

55
Q

This is an image of? Also, what is the arrow pointing to?

A

Non-communicating Hydrocephalus

It is pointing to a large mass in posterior fossa

56
Q

Fat appears bright on T1 weighed. What is it good for?

A

Good for detecting bone marrow pathology

57
Q

DWI (MRI)

A

–Acute stroke is bright

–Great for detecting very early acute infarct (within 10 to 60 minutes)

58
Q

SWI (MRI)

A

•Susceptabilityweighted

–Blood is very dark

–Very good for detecting hemorrhage

59
Q

Chronic Stroke taken by MRI T2

A
60
Q

CT angiogram

A