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Neuroradiology > Quick stuff > Flashcards

Quick stuff Flashcards

1
Q

Classification of the traumatic primary hemorrhages caused directly and immediately by the impact

A
  • Epidural hematoma (arterial/venous) , more acute
  • Subdural hematoma (Extra-axial), more chronic
  • Intracerebral hematoma
  • Intraventricular hemorrhage
  • Subarachnoid hemorrhage
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2
Q

What can epidural and subdural hematoma be classified as?

A

Primary extra-axial traumatic injury

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3
Q

What causes epidural hematoma?

A

Caused by the tearing of (arterial) vessels (more often middle meningeal artery caused by trauma on the temporal or fronto-parietal bone) by depressed bone planks

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4
Q

Which preceding event is associated with development of epidural hematoma?

A

Almost always associated with
fractures

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5
Q

Epidural hematoma incidence bilateral vs unilateral

A

Generally, it is monolateral but it can exceptionally be bilateral but there would need to be 2 fractures on each side

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6
Q

Where does blood collect in epidural hematoma?

A

Blood collects between the internal skull surface and the outer layer of the dura mater (endosteal layer)

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7
Q

Location of epidural hematoma

A
  • Supratentorial in 95% of cases
  • Temporoparietal: 60%
    frontal: 20%
    parieto-occipital: 20%
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8
Q

How does epidural hematoma appear on CT scan?

A
  • Hyperdense, somewhat heterogeneous, and sharply demarcated
  • Hypodense areas in hyper-acute stage are indicative of active bleeding (not yet coagulated
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9
Q

Shape of epidural hematoma

A

Typically biconvex in shape (biconcave lens)

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10
Q

Which imaging for epidural hematoma

A

Both CT and MRI (rarely necessary and done0 are suitable to evaluate EDHs

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11
Q

How does epidural hematoma appear on MRI?

A
  • Acute EDH appears isointense on T1 and shows variable intensities from hypo- to hyperintense on a T2 sequence
  • Early subacute EDH appears hypointense on T2 while late subacute and chronic EDH are hyperintense on both T1 and T2 sequences
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12
Q

What causes subdural hematoma?

A
  • Caused by the tearing of cortical veins, which are the ones connecting the Dural sinuses, adjacent to bone, with the small veins inside the brain parenchyma
  • The blood accumulates in the subdural space (normally virtual) between the dura mater and the arachnoid
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13
Q

What event leads to subdural hematoma?

A

Mainly due to head trauma

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14
Q

Imaging choice for subdural hematoma?

A

CT is usually sufficient to make diagnosis

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15
Q

Bilateral vs unilateral subdural hematoma incidence?

A
  • Most are unilateral in adults
  • Most are bilateral in infants
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16
Q

Site of subdural hematoma

A
  • They are mainly supratentorial (like epidural ones), staying along the frontoparietal area
  • Frontoparietal convexities and the middle cranial fossa
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17
Q

Subdural hematoma appearance on CT

A
  • The appearance of SDHs on CT varies with clot age and organization.
  • Shift of the midline can be seen
  • Hyperacute (first hour or so): relatively isodense to the adjacent cortex, with a swirled appearance due to a mixture of the clot, serum and ongoing unclotted blood
    Acute: Crescent-shaped homogeneously hyperdense extra-axial collection that spreads diffusely over the affected hemisphere
    Up to 40% of SDHs have mixed hyper- or hypodense areas that reflect unclotted blood, serum extruded during clot retraction, or CSF within the subdural hematoma due to an arachnoid laceration.
    Subacute
    typically 10-14 days, the density become isodense to the adjacent cortex, making identification potentially tricky. Contrast-enhanced CT is often useful in this instance if MRI is unavailable
    Chronic (at least 3 weeks old): The subdural collection becomes hypodense to the adjacent cortex with possibility of reaching isodensity to CSF, and mimic a subdural hygroma.
    Acute on chronic
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18
Q

What is acute on chronic subdural hematoma?

A

Acute on chronic subdural hematomas refers to a second episode of acute hemorrhage into a pre-existing chronic subdural hematoma. It typically appears as a hypodense collection with a hematocrit level (located posteriorly). A similar appearance can be seen in patients with clotting disorders or on anticoagulants

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19
Q

MRI subdural hematoma

A

Hyperacute
T1: isointense to grey matter
T2: iso- to hyperintense
FLAIR: hyperintense to CSF
Acute
T1: iso- to hypointense to grey matter
T2: hypointense to grey matter
FLAIR: hyperintense to CSF

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20
Q

CT findings subarachnoid hemorrhage

A

acute blood is hyperdense (bright) on CT
blood in the basal cisterns and sulci

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21
Q

What is the most common tumor of the meninges?

A

Meningiomas

22
Q

What are meningiomas?

A

Non-glial neoplasm that originates from the meningocytes or arachnoid cap cells

23
Q

How many subtypes of meningiomas exist?

A

15 subtypes

24
Q

How do meningiomas appear on imaging?

A

Typical meningiomas appear as dural-based masses isointense to grey matter on both T1 and T2 weighted imaging enhancing vividly on both MRI and CT

25
Q

Location of meningiomas

A
  • Can occur anyhwere along meninges
  • Most are supratentorial
26
Q

Choice of imaging for meningiomas and why?

A
  • MRI is the investigation of choice for the diagnosis and characterization of meningiomas
  • Best imaged with MRI with contrast as this most accurately delineates the tumor, presence of intra- and trans-osseous extension and relationship to the underlying brain
  • CT, however, is useful if bony anatomy is required (e.g. at the base of skull), when patients cannot have MRI, and especially when the meningioma is entirely ossified/calcified
27
Q

Appearance of meningiomas on MRI

A
  • Extra-axial masses with a broad dural base
  • They are usually homogeneous and well-circumscribed, although many variants are encountered
    correlates with the histological subtypes
  • T1: usually isointense to grey matter (60-90%)
    hypointense to grey matter (10-40%): particularly fibrous, psammomatous variants
  • T1 C+ (Gd): usually intense and homogeneous enhancement
  • T2: It seems that the signal intensity of meningiomas on T2-weighted images correlates with the histological subtypes. usually isointense to grey matter (~50%),
    hyperintense to grey matter (35-40%) (microcystic, secretory, cartilaginous (metaplastic), chordoid and angiomatous variants),
    hypointense to grey matter (10-15%)
  • Dural tail is seen in 60-72% (note that a dural tail is also seen in other processes)
  • white matter buckling sign
28
Q

Which intracranial intra axial tumor is most common?

A

Gliomas

29
Q

Location of gliomas

A

1/2 are supratentorial, ¼ are infratent

30
Q

Primary vs metastatic glioma incidence

A

60% or less are primary, 40% of them are metastatic.

31
Q

WHO classification of gliomas

A

Four grades:
1- Pilocytic astrocytoma
2- Fibrillary astrocytoma
3- Anaplastic astrocytoma
4- Glioblastoma (glioblastoma multiforme represents 50% of all gliomas and 25% of primitive tumors of the brain

32
Q

What can gliomas of the cerebral hemispheres be divided into?

A

Circumscribed (grade 1) and diffuse (or infiltrative)

33
Q

What is included in circumscribed glioma?

A

Pilocytic astrocytoma, subependymal giant cell astrocytomas, and desmoplastic infantile ganglioma

34
Q

What is included in the diffuse gliomas?

A
  • Fibrillary astro-oligodendroglioma (and protoplasmic) grade II
  • Anaplastic astro-oligodendroglioma (and gemistocytic) grade III
  • Glioblastoma (GBM) grade IV (worse of all)
35
Q

Purpose and targets of radiology in cerebral gliomas

A

Neuroradiological purpose and targets of cerebral gliomas are:
* Identification and localization for surgical treatment
* Extension evaluation
* Hypothesis on origin and grading
* Risk evaluation and neurosurgical options
* Follow-up after treatment. This is important to know whether the tumor remain stable
or there is evidence of regrowth.

36
Q

Neuroradiological features of glioblastoma multiforme

A
  • White matter localization (because it comes from the glial cells)
  • Extremely heterogeneous MRI signal with central necrosis
  • It shows hyperintense signal on T2-weighted image, but the peripheral portion shows
    lower signal intensity.
  • It shows irregular margin and contrast enhancement, which tends to circumscribe the
    necrosis.
  • Common features: various stages of hemorrhage (time framed), high vascularization,
    and adjacent blood vessel dilation.
  • The use of PWI and DWI allow us to see increased cerebral blood volume and high
    cellularity of solid components respectively.
  • The use of MRS shows elevated Choline and lactate/Lip (necrosis)
37
Q

DTI usefulness in glioblastoma

A

see tumor’s influence on fiber tracts and plan for surgery

38
Q

Differential diagnosis between grade 2 and 3 and 4 glioma

A
  • The differential diagnosis between grade II astrocytoma and glioblastoma is easy and it’s based on: T2 signal, contrast enhancement and morphological characteristics. The difficult one is the differential diagnosis between grade II and grade III.
  • We look for presence of contrast enhancement in tumors. When we find the glioma with contrast enhancement (as shown on the right), it’s generally grade III already.
  • Up to 25% malignant gliomas without contrast enhancement can be seen. In some rarer cases low grade diffuse gliomas can show contrast enhancement.
  • With the perfusion-weighted images, we see that blood uptakes on both sides are similar in benign tumor, but they are different in the malignant tumors (increased inner vascularization)
  • Grade II gliomas perfusion will be stable over time.
39
Q

Clinical importance of differentiating between grade 2 and 3 gliomas?

A

Important clinical impact: malignant gliomas need aggressive treatments, but low-grade gliomas, in young adult patients without neurologic signs, do not justify the risk for surgery.

40
Q

Progressive supranuclear palsy

A
  • The prevalent MRI finding is midbrain atrophy, with dilation and downwards expansion of the third ventricle.
  • Flattening or concave outline to the superior aspect of the midbrain, which should be upwardly convex, and reduction of the roof thickness makes the “hummingbird” or “penguin” sign
  • The prevalent MRI finding is midbrain atrophy, with dilation and downwards expansion of the third ventricle.
     Flattening or concave outline to the superior aspect of the midbrain, which should be upwardly convex, and reduction of the roof thickness makes the “hummingbird” or “penguin” sign
41
Q

Parkinson’s disease imaging findings

A
  • Reduced thickness of substantia nigra pars compacta
  • common finding is the reduction of thickness of the pars compacta of the substantia nigra (T2/T2*w)
  • Absent swallow tail sign (SWI protocol)
42
Q

Role of imaging in Parkinson’s disease

A
  • In idiopathic forms usually there are not specific findings
  • The role of neuroradiology consists mainly in the evaluation of atrophy and of the overall parenchymal vascular lesion load”,and in the exclusion of secondary forms
43
Q

How much does schwannoma account for intracerebral tumors?

A
  • Represent the vast majority (70%) of lesions in the
    cerebellopontine cisterns and 5-10% of all intracerebral tumors
  • Most common extracranial tumors in
    the posterior cranial fossa
44
Q

Origin of schwannoma

A

In most cases originates from the vestibular branch of the eight cranial nerve, arising generally within the internal acoustic canal, and is centered on IAC

45
Q

Age of occurence of Schwannoma

A

Mainly between 30 and 60 years and could be
bilateral.

46
Q

Imaging characteristics of schwannoma

A
  • Common to see an ice cream cone shape when the tumor is inside the IAC
  • No hyperostosis or calcification
  • Variable MRI signal: Sometimes it’s hypointense on T1 weighted images and hyperintense on T2-WI
47
Q

Where would bilateral schwannomas be typically seen?

A

Neurofibromatosis 2

48
Q

CPA cisternal tumors types

A
  • Schwannoma 70%
  • Meningioma 15-20%
49
Q

CPA meningioma imaging

A
  • It produces obtuse angles with the petrous part of the temporal bone. The common shape is “mushroom cap-shaped.”
  • Generally, on CT, we look for the presence of calcifications inside the tumor or possible hyperostosis of the surface of the bone where benign tumor is located, while aggressive meningiomas (grade 2/3) tend to infiltrate. Isointense MRI signal in T1 and T2 weighted images
50
Q

Location of CPA meningioma

A

It tends to be based on the petrous part of the
temporal bone or on tentorium or on petroclinoid ligament;

Neuroradiology (1 decks)

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