Quick stuff

Question 1

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

Answer 1

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

Question 2

What can epidural and subdural hematoma be classified as?

Answer 2

Primary extra-axial traumatic injury

Question 3

What causes epidural hematoma?

Answer 3

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

Question 4

Which preceding event is associated with development of epidural hematoma?

Answer 4

Almost always associated with
fractures

Question 5

Epidural hematoma incidence bilateral vs unilateral

Answer 5

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

Question 6

Where does blood collect in epidural hematoma?

Answer 6

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

Question 7

Location of epidural hematoma

Answer 7

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

Question 8

How does epidural hematoma appear on CT scan?

Answer 8

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

Question 9

Shape of epidural hematoma

Answer 9

Typically biconvex in shape (biconcave lens)

Question 10

Which imaging for epidural hematoma

Answer 10

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

Question 11

How does epidural hematoma appear on MRI?

Answer 11

• 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

Question 12

What causes subdural hematoma?

Answer 12

• 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

Question 13

What event leads to subdural hematoma?

Answer 13

Mainly due to head trauma

Question 14

Imaging choice for subdural hematoma?

Answer 14

CT is usually sufficient to make diagnosis

Question 15

Bilateral vs unilateral subdural hematoma incidence?

Answer 15

• Most are unilateral in adults
• Most are bilateral in infants

Question 16

Site of subdural hematoma

Answer 16

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

Question 17

Subdural hematoma appearance on CT

Answer 17

• 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

Question 18

What is acute on chronic subdural hematoma?

Answer 18

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

Question 19

MRI subdural hematoma

Answer 19

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

Question 20

CT findings subarachnoid hemorrhage

Answer 20

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

Question 21

What is the most common tumor of the meninges?

Answer 21

Meningiomas

Question 22

What are meningiomas?

Answer 22

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

Question 23

How many subtypes of meningiomas exist?

Answer 23

15 subtypes

Question 24

How do meningiomas appear on imaging?

Answer 24

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

Question 25

Location of meningiomas

Answer 25

- Can occur anyhwere along meninges - Most are supratentorial

Question 26

Choice of imaging for meningiomas and why?

Answer 26

- 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

Question 27

Appearance of meningiomas on MRI

Answer 27

- 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

Question 28

Which intracranial intra axial tumor is most common?

Answer 28

Gliomas

Question 29

Location of gliomas

Answer 29

1/2 are supratentorial, ¼ are infratent

Question 30

Primary vs metastatic glioma incidence

Answer 30

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

Question 31

WHO classification of gliomas

Answer 31

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

Question 32

What can gliomas of the cerebral hemispheres be divided into?

Answer 32

Circumscribed (grade 1) and diffuse (or infiltrative)

Question 33

What is included in circumscribed glioma?

Answer 33

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

Question 34

What is included in the diffuse gliomas?

Answer 34

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

Question 35

Purpose and targets of radiology in cerebral gliomas

Answer 35

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.

Question 36

Neuroradiological features of glioblastoma multiforme

Answer 36

- 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)

Question 37

DTI usefulness in glioblastoma

Answer 37

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

Question 38

Differential diagnosis between grade 2 and 3 and 4 glioma

Answer 38

* 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.

Question 39

Clinical importance of differentiating between grade 2 and 3 gliomas?

Answer 39

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.

Question 40

Progressive supranuclear palsy

Answer 40

- 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

Question 41

Parkinson's disease imaging findings

Answer 41

- 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)

Question 42

Role of imaging in Parkinson's disease

Answer 42

- 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

Question 43

How much does schwannoma account for intracerebral tumors?

Answer 43

- 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

Question 44

Origin of schwannoma

Answer 44

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

Question 45

Age of occurence of Schwannoma

Answer 45

Mainly between 30 and 60 years and could be bilateral.

Question 46

Imaging characteristics of schwannoma

Answer 46

- 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

Question 47

Where would bilateral schwannomas be typically seen?

Answer 47

Neurofibromatosis 2

Question 48

CPA cisternal tumors types

Answer 48

- Schwannoma 70% - Meningioma 15-20%

Question 49

CPA meningioma imaging

Answer 49

- 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

Question 50

Location of CPA meningioma

Answer 50

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