14. Intro to Neuroradiology Flashcards

1
Q

List the imaging modalities available for neurological imaging.

A
  1. Radiography (X-Ray)
  2. Fluoroscopy
  3. Ultrasound
  4. ComputedTomography(CT)
  5. Magnetic Resonance (MR)
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2
Q

Explain how computed tomography creates images and how these images are read (e.g. are cross sections viewed from an inferior or superior view).

A

CT takes a. series of X-rays that are scanned axially and then lets you digitally re-slive in image in ANY place.

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3
Q

Describe the Hounsfield scale and how adjustments can be made so different tissues and anomalies can best be viewed (e.g. compare a soft tissue window vs a bone window).

A
  • When looking at CT’s, we measure the radiodensity because we are measuring the absorbed radiation. Radiodensity is measured in Hounsfields units (HU) relative to water, which is 0 HU.
    • Hypodense: white/bright
    • Hyperdense: black/dark
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4
Q

Describe the Hounsfield scale and how adjustments can be made so different tissues and anomalies can best be viewed (e.g. compare a soft tissue window vs a bone window).

A

To look at tissue or bone, you can adjust the window and level.

  • Window is the width of the HU.
    • Wider windows are used to compare areas with different HU (bone vs. air),
    • Smaller windows are used to measure things with similar H.Us (brain vs. blood)
  • Level is the center of the window.
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5
Q

Window of bones, air and tissue?

A
  1. +1000 HU
  2. -1000 HU
  3. +30-40
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6
Q

Bone window: most common

A

W: 1000HU L:400HU

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7
Q

Soft tissue window: most common

A

W:350HU

L:40HU

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8
Q

Explain how magnetic resonance imaging is utilized to produce an image.

A
  • Patients lies in a large magnet, which aligns all the protons (i.e. Hydrogen or water molecules) in the body
  • Radiowaves are then passed through the patient and returning signals are converted into an image.
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9
Q

How do we describe MRIs?

A
  1. Hyperintense: white/bright
  2. Hypointense: black/dark
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10
Q

Explain the difference between T1 and T2 weighted MR.

A

T1 is good for looking at anatomy.

  • CSF is dark (hypointense)
  • White matter is bright (hyperintense)

T2

  • CSF is bright (hyperintense)
  • White matter is dark. (hypointense)
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11
Q

What is a T2 FLAIR (FLuid Attenuated Inversion Recovery)?

A

Removes CSF from a T2 image and leave you with soft tissue.

This enhances the fluid that is NOT CSF; that with a different protein coponent.

This is good for looking at edema and strokes.

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12
Q

Identify the primary differences between plain film X-ray and fluoroscopy and when one is preferred over the other.

A
  • Fluoscopy has the same process as a X-ray. However, it is a real time x-ray.
  • Continuous X-ray radiation passes through the body only a fluroscent screen to creat. a. moveing X-ray image.
  • Also causes contrast
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13
Q

Identify the primary differences between plain film X-ray and fluoroscopy and when one is preferred over the other.

A

Xrays: use for

  1. trauma (fracture),
  2. degenerative diseases (RA),
  3. post-op checks

Fluroscopy: used for

  1. diagnosis and intervention;
    1. swallow studies,
    2. angiography
    3. myelography
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14
Q

List the different types of contrast used in neurological imaging.

Base?

Fx:

Cons:

A
  1. CT contrast is iodine based.
  • absorbs X rays
  • Con: risk of anaphylaxis, allergic reactions or contrast induced neuropathy
  1. MRI contrast is gadolinium based
    * Gadolinium is a paramagnetic metal that increases T1 relaxation of nearby water

protons (bright on MRI).

  • Cons: If a person has renal insuffiency and gadolinium is aborbed by. kidneys -> causes systemic fibrosis
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15
Q

what structures are enhanced with IV contrast.

REMEMBER: only tissue that gets brighter with CONTRAST enhances; it reflects that vascularity of the tissue.

A
  1. Cerebral blood vessels
  2. Meninges
  3. Pineal gland
  4. Pituiary. gland
  5. Choroid plexus
  6. Use when performing fluroscopy
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16
Q

When do we do CT w or w/o contrast

A
  1. Non-contrast CT use used in patients with head/spine trauma or acute stroke. It is the fastest test in MRGNC situations. It is the preferred test within 3 hours of acute symptom onset.
  2. Contrast CT is used when sx last longer than 3 hours: neoplasm, infection, vascular disease, inflammatory disease.
17
Q

YES OR NO CT WITH IV CONTRAST

  1. Trauma
  2. neoplasm
  3. infection
  4. Rule out Hemorrhage
  5. vascular disease
  6. Hydrocephalus
  7. Dementia
  8. inflammatory disease
  9. Epilepsy
A

NO IV contrast:

  1. Trauma
  2. Rule out Hemorrhage
  3. Hydrocephalus
  4. Dementia
  5. Epilepsy

YES IV contrast:

  1. Neoplasm
  2. infection
  3. Vascular disease
  4. Inflammartory disease
18
Q

What. happens if brain parenchyma is enhanced

A
  • Enhancement in brain parenchyma is indicative the BBB is absent or dysfunctional (tumors, inflammation, infarction).
19
Q

Compare and contrast the various neuroimaging modalities in regards to indications, advantages and disadvantages.

  1. Xrays (radiography)
    1. Use for:
    2. Pro:
    3. Con:
  2. Fluroscopy (barium swallow, angiography, myelography)
A

X rays are used for: trauma (fractures), degenerative diseases, post-op checks

Pro: cheap and fast

Cons: uses radiation and cant see detail of soft tissue

Fluorscopy:

  1. Barium swallow test
    1. Used: dysphagia, epigastric pain, GERD
    2. Pro: shows us live swallowing
    3. Cons: time consuming, uses contrast, radiation
  2. Angiography
    1. Used: aneurisms, vascular malformations, stenosis, thrombosis, stenting, embolization, thrombylysis
    2. Pro: can intervene and fast
    3. Con: invasive, uses contrast. and radiation
  3. Myelography (cervical or lumbar puncture to inject contrast -> follow with CT to eval)
    1. Used for: spinal stenosis, nerve root compression, CSF leak, if MRI is contraindicated
    2. Pro: defines our subarachnoid space and identifies spinal block
    3. Cons: invasive, complications (CSF leak-> HA), radiation (bc must follow up with CT) , contrast
20
Q

Compare and contrast the various neuroimaging modalities in regards to indications, advantages and disadvantages.

US

Use for:

Pro:

Con:

A

Use for: carotid stenosis, brain imaging for BBs

Pro: non-invasive, cheap and fast. Quantitates blood velocity

Con: operator must learn to use with experience, limited penetration through air or bone

21
Q

Compare and contrast the various neuroimaging modalities in regards to indications, advantages and disadvantages.

CT

Use for:

Pro:

Con:

A

Used for:

  1. Trauma, bone lesions of skull and vertebrea
  2. Ventricles: Hydrocephalus, masses, mass effect
  3. Intracrania lmasses,mass effect; if pt comes in with N/V, HA, vzn problems
  4. Hemorrhage, ischemia (stroke, mental status change,
  5. Calcification

Pros: FAST and Cheap

Cons:

  1. Less detail
  2. Radiation
  3. Low sensitivity in posterior fossa
22
Q

MRI

Used for:

Pros:

Cons:

A

Used for:

    1. further evaluate findings in CT;
    1. chronic, subacute sx
    1. Tumors, masses
    1. Infections (absess, meningitis, encephalitiis

Pro: more detail, safe in pregnancy, no constrast

Cons: slower, more contraindications (metal in body), expensive, patient must hold still

23
Q

What provides the GREATEST AMOUNT OF DETAIL (better than contrast enhanced CT when evaluating ischemia)?

A

MRI

24
Q

What is the most beneficial for ruling out large pathology (bleed, large ischemic stroke, mass, abscess, hydrocephalus)?

A

CT; bc fast and cheap.

However, MRI provides the greatest detail, just is slower, more contraindications, expensive.

25
Q
A