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Radiology Journal Club > More brain > Flashcards

More brain Flashcards

1
Q

What are imaging characteristics of a mucocele?

Imaging diagnosis - IC mucocele in a dog. VRU 49.6

A

Similar to an abscess
T2/FLAIR hyperintense
T1 - isointense
Peripheral ring enhancement

Abscesses generally have more perilesional edema, cystic core

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2
Q

Why do mucoceles form?

Imaging diagnosis - IC mucocele in a dog. VRU 49.6

A

buildup of mucus secretions with cyst formation
Occur secondary to occlusion of nasofrontal duct caused by inflammation, fibrosis, trauma, congenital abnormality or neoplasia

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3
Q

What is an empty sella? how was it graded?

MRI features of empty sella in dogs. VRU 49.4

A

Absent or reduced pitutiary siz.
Hypophyseal tissue filling more than 50% of the sella - normal
30-50% - partial empty sella

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4
Q

In humans, what clinical symptoms correspond with empty sella syndrome?

Do dogs have similar symptoms?

MRI features of empty sella in dogs. VRU 49.4

A

pituitary insufficiency, hypertension, headache, CSF leakage (hydrocephalus), increased, benign intracranial pressure

Dogs did not have similar symptoms or evidence of pituitary insufficiency

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5
Q

What are the different forms of empty sella syndrome?

MRI features of empty sella in dogs. VRU 49.4

A

Primary - incomplete formation

Secondary - adenoma with necrosis, infarction, infection, autoimmune disease, iatrogenic

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6
Q

Is there an association with empty sella syndrome and ventriculomegaly?

MRI features of empty sella in dogs. VRU 49.4

A

No.

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7
Q

How is normal ventricle size measured via US or MRI?

Is there clinical signs associated with degree of ventriculomegaly?

MRI features of empty sella in dogs. VRU 49.4
US imaging of the lateral cerebral ventricles in dogs VRU 31.2

A

Ratio between ventricular height and height of brain
25% - severe ventriculomegaly

No association between ventriculomegaly and clinical signs.

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8
Q

What is the normal width and height of a dog pituitary gland?

Is there association between body weight, brain size and pituitary size?

Mensuration of normal pituitary gland from MRI in 96 dogs. VRU 42.2.

A

5mm height
6.5mm width

No association between pituitary size, body weight, brain volume/size.

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9
Q

What is normal width, height and length of a cat pituitary gland?

What is normal volume?

Is there significance between age, body weight, and pituitary size?

Mensuration of normal pituitary gland from MRI in 17 cats. VRU

A

Width: 5mm
Height: 3.4mm
Length: 5.5mm

Volume: 0.05cm^3

No association

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10
Q

What percentage of cats will have multiple meningiomas?

Imaging diagnosis - synchronous primary brain tumors in a dog VRU 48.6

A

17%

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11
Q

What are primitive neuroectodermal tumors?

Imaging diagnosis - synchronous primary brain tumors in a dog VRU 48.6

A

Another term for medulloblastoma

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12
Q

What is Dandy-walker malformation?

Imaging diagnosis - dandy walker malformation VRU 49.3

A

Congenital malformation of the CNS - most notably the cerebellum and adjacent tissues

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13
Q

What characteristics do most Dandy-walker malformations have?

Imaging diagnosis - dandy walker malformation VRU 49.3

A

Absent/small cerebellar vermis
Cystic malformation of the fourth ventricle
Enlargement of the posterior fossa

Other variants: cystic malformation of 4th ventricle without enlargement of posterior fossa, enlargement of cisterna magna with compression/atrophy of cerebellum

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14
Q

What is the triad of findings associated with Dandy-Walker Syndrome?

US appearance of Dandy-walker-like syndrome in a boston terrier. VRU 45.4

A

Hydrocephalus
Vermian hypoplasia
Cysts associated with the fourth ventricle

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15
Q

What breed may be predisposed to Dandy-walker syndrome?

A

Boston terriers

US appearance of Dandy-walker-like syndrome in a Boston terrier. VRU 45.4

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16
Q

What is characteristic signalment/history of feline hippocampal necrosis?

MRI of feline hippocampal necrosis VRU 49.4

A

Animals of any age
Cats from switzerland or italy
Generalized/complex seizures

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17
Q

What is appearance of hippocampal necrosis on MRI in felines?

MRI of feline hippocampal necrosis VRU 49.4

A

Hippocampus and piriform lobe T2 hyperintense, T1 hypointense and various degrees of contrast enhancement

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18
Q

What are MRI characteristics of an epidermoid cyst?

Imaging diagnosis - IC epidermoid cyst in a Doberman pinscher - VRU 48.3

A

This is different from other article: Canine IC epidermoid cyst VRU 40.4

T2: hyperintense - similar to CSF
FLAIR: hyperintense
No edema
T1 - hypointense
T1 +C - +/- rim enhancement
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19
Q

Where do epidermoid cysts most commonly occur?

Imaging diagnosis - IC epidermoid cyst in a Doberman pinscher - VRU 48.3

A

cerebellopontine angle - 40-50%
4th ventricle - 15%
sellar fossa - 10-15%

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20
Q

What are imaging differences between epidermoid cysts vs dermoid cyst vs arachnoid cyst?

Imaging diagnosis - IC epidermoid cyst in a Doberman pinscher - VRU 48.3

A 
Epidermoid cyst:
T2: hyperintense - similar to CSF
FLAIR: hyperintense
No edema
T1 - hypointense
T1 +C - +/- rim enhancement

Dermoid cyst: Hyperintense in T1 and T2 due to high fat content

Arachnoid cyst: hypointense on FLAIR, similar to CSF.

Epidermoid cysts have higher signal on FLAIR due to protein/cholesterol content

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21
Q

What are imaging characteristics of a dermoid cyst within the medulla?

MRI of a medullary dermoid cyst with secondary hydrocephalus in a dog. VRU 40.1

A

T1 - dramatically hyperintense (pre-contrast)
T2 - hyperintense
**both T1 and T2 had patchy regions of low signal - likely due to presence of hair, sweat, glandular tissue
Post contrast - no enhancement
No edema

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22
Q

Why are dermoid cysts hyperintense on T1 weighted images?

MRI of a medullary dermoid cyst with secondary hydrocephalus in a dog. VRU 40.1

A

Presence of fat

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23
Q

What are reasons for hyperintense on pre contrast T1 images?

MRI of a medullary dermoid cyst with secondary hydrocephalus in a dog. VRU 40.1

A

Fat
Slow flowing blood
Melanin
Hemorrhage - early/late subacute phase - due to methemoglobin

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24
Q

How do you differentiate between pure fat lipomas and dermoid cysts?

MRI of a medullary dermoid cyst with secondary hydrocephalus in a dog. VRU 40.1

A

Lipomas are more uniform -will completely suppress with STIR images
Can be difficult if dermoids are highly fatty

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25
Q

How do you weed out why a lesion may be hyperintense on T1 pre contrast images?

MRI of a medullary dermoid cyst with secondary hydrocephalus in a dog. VRU 40.1

A

Hemorrhage - rule out with T2 - will generally be hypointense, or by using the STIR image - dermoid will suppress

Melanin - will be hypointense on T2 images

Pure fat lipomas are generally more homogeneous than dermoid cysts

Slow flowing blood - flow-sensitive imaging techniques

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26
Q

What are the imaging characteristics of an intracranial epidermoid cyst?

Canine IC epidermoid cyst VRU 40.4

A

T2 hyperintense
T1 - hypointense
+/- hydrocephalus
+/- rim enhancement

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27
Q

How do dermoid and epidermoid cysts form?

Canine IC epidermoid cyst VRU 40.4

A

During fusion of the neural tube - the non-neuroectoderm components (epithelial stuff) are not fully separated

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28
Q

How frequently do dogs with IC epidermoid cysts exhibit clinical signs.. and if so - which CN are affected?

Canine IC epidermoid cyst VRU 40.4

A

Previous reports - 50% cysts were incidental findings

Cranial nerve 8 is most common, often have 5 involvement

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29
Q

What are secondary complications associated with IC epidermoid cysts?

Canine IC epidermoid cyst VRU 40.4

A

Chemical meningitis, malignant transformation into SCC, foreign body giant cell reactions

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30
Q

What are MR characteristics of an IC intra-arachnoid cyst

MRI and CT characteristics of intracranial intra-arachnoid cysts in 6 dogs VRU 38.3

A

Hyperintense on T2 - similar to CSF
T hypointense
No enhancement post contrast (including walls or contents)

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31
Q

Where are intra-arachoid cysts most commonly found?

MRI and CT characteristics of intracranial intra-arachnoid cysts in 6 dogs VRU 38.3

A

Quadrigeminal cistern

Cerebellomedullary angle

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32
Q

What are CT characteristics of IC intra-arachnoid cysts?

MRI and CT characteristics of intracranial intra-arachnoid cysts in 6 dogs VRU 38.3

A

Cysts were isodense to CSF

No enhancement of the cyst walls

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33
Q

What other differentials for a cystic lesion in caudal fossa should you have?

MRI and CT characteristics of intracranial intra-arachnoid cysts in 6 dogs VRU 38.3

A

Cystic neoplasms (gliomas, meningiomas, astrocytomas, metastatic tumors)
Cysts with infectious disease (abscess, hydatid cyst)
Non-neural epithelial cysts (epidermoid/dermoid)
Dysgenic (Dandy walker)
Porencephalic cysts

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34
Q

What are typical post-ictal changes seen on MRI of dogs, and why do they think they occur?

Reversible MRI abnormalities in dogs following seizures VRU 40.6

A

Bilateral/symmetrical T2 hyperintense/T1 hypointense changes associated with the temporal and piriform lobes with no mass effect

+/- enhancement

Associated with cytotoxic/vasogenic edema. Gliosis in humans

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35
Q

What are other changes seen on recheck MRIs on dogs with changes in piriform lobe/temporal lobe?

Reversible MRI abnormalities in dogs following seizures VRU 40.6

A

Cystic structures in frontal lobes/olfactory bulbs - not sure why they occur.

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36
Q

Common findings of intracranial blastomycosis?

Clinical and MRI features of CNS blastomcyosis in 4 dogs JVIM 24

A

T2 hyperintense (majority) - most commonly extra-axial
T2 rim enhancement with central region (due to clusters of organisms)
T1 hypointense
Marked perilesional edema
Contrast enhancement

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37
Q

In contrast to previous reports which only describe mass-like lesions, what other MR findings can be seen with intracranial blastomycosis?

A

Periventricular edema, periventricular and meningeal contrast enhancement of the rostral horns, lateral ventricles, and third ventricle.

Ependymal and periventricular MRI changes in 4 dogs with CNS blastomycosis VRU 54.5

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38
Q

What disease processes have described periventricular/ependymal hyperintensities on MR?

A 
Blastomycosis
Necrotizing encephalitis in Yorkies
Bacterial infections
FIP
Cryptococcus
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39
Q

Previous reports described what changes in cases of Neospora?

MRI characteristics in 4 dogs with CNS neosporosis VRU 55.4

A

bilateral, symmetrical cerebellar atrophy (prominent folia)

T2 hyperintensity and contrast enhancement of temporalis and masseter muscles

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40
Q

What were common findings in the dogs reported in this article:
MRI characteristics in 4 dogs with CNS neosporosis VRU 55.4

A

Bilateral, symmetrical cerebellar atrophy
Multifocal, intra-axial T2 hyper/T1 hypo, with peripheral enhancement with small amount of peri-lesional edema
Intramedullary spinal cord lesions with similar characteriscs

41
Q

Where are common locations for gliomatosis cerebri and how does this compare to humans?

MRI features of gliomatosis cerebri in a dog VRU 53.2

A

Cerebellum and cerebrum.

Humans - generally affect the cerebrum and portions of brainstem

42
Q

What are common imaging features of gliomatosis cerebri?

MRI features of gliomatosis cerebri in a dog VRU 53.2

A

Ill-defined T2/FLAIR hyperintensity of cerebrum/cerebellum
Iso/hypointense T1
Generally absent contrast enhancement. If there is enhancement - suggests severe/advanced disease

43
Q

What are other differential diagnoses for a gliomatosis cerebri lesion?

MRI features of gliomatosis cerebri in a dog VRU 53.2

A

Diffuse astrocytoma, oligodendroglioma, infectious/inflammatory , demyelinating disease (multiple sclerosis), leukoencephalopathies

44
Q

What is type 1 vs type 2 gliomatosis cerebri?

MRI features of gliomatosis cerebri in a dog VRU 53.2

A

Type 1 - classic form - CNS infiltration of neoplastic cells without formation of a focal mass
Type 2 - diffuse infiltration accompanied by a focal mass (high grade glioma)

45
Q

What are the types of CVA?

Comparative MRI findings between gliomas and presumed CVA in dogs. VRU 52.1

A

Ischemic and hemorrhagic
Ischemic are most common: non-hemorrhagic and hemorrhagic (hemorrhage is secondary to reperfusion and damaged endothelium of vessels)

46
Q

What are the causes of different types of CVA?

Comparative MRI findings between gliomas and presumed CVA in dogs. VRU 52.1

A

Ischemic: disturbance to arterial supply/venous drainage by thrombus, embolus, or secondary to vessel abnormalities, hypoperfusion

Hemorrhagic: hypertension, aneurysm

47
Q

Where do gliomas vs CVA most commonly occur?

Comparative MRI findings between gliomas and presumed CVA in dogs. VRU 52.1

A

Gliomas: Most common in cerebrum. Not seen in cerebellum

CVA: cerebellum is most common, but can also occur in brainstem, cerebrum, thalamus,

48
Q

What are major imaging differences that may lead you to diagnose glioma vs CVA?

Comparative MRI findings between gliomas and presumed CVA in dogs. VRU 52.1

A

Glioma - marked perilesional edema, round/ovoid in shape (never wedged)

CVA - less edema, round/ovoid/wedge,

Biggest difference was in ADC maps:
CVA - DWI: bright, ADC: dark
Glioma - Bright on both

49
Q

What is reasoning between why CVA imaging changes on DWI and ADC

What about gliomas?

Comparative MRI findings between gliomas and presumed CVA in dogs. VRU 52.1

A

Most common finding: DWI (dark), ADC (bright) - consistent with cytotoxic edema - reduced Brownian motion

Mixed intensities on ADC - due to reperfusion - creates higher signal on ADC - vasogenic edema - increased water content, with no decrased motion of water

Glioma - Bright on both - due to T2 shine through from necrosis, degeneration, hemorrhage

50
Q

What imaging sequence helped determine between glioma and CVA?

How much did this help?

Comparative MRI findings between gliomas and presumed CVA in dogs. VRU 52.1

A

DWI and ADC

10-47% CVA were mis-diagnosed as gliomas
0-12% gliomas were mis-diagnosed as CVA

with ADC
11-33% CVA were mis-diagnosed as glioma
0% gliomas were mis-diagnosed as CVA

51
Q

What two main blood vessels supply the brain in the dog?
Where do these vessels originate?

MRI findings of presumed cerebllar CVA in 12 dogs VRU 46.1

A

Internal carotid - common carotid branches into external and internal at approximately the retropharyngeal LN

Basilar artery - formed by terminal branches of vertebral arteries

52
Q

Which type of brain tissue do CVA most common affect?

Comparative MRI findings between gliomas and presumed CVA in dogs. VRU 52.1

A

Gray matter

53
Q

When do CVA cause mass effects?

Comparative MRI findings between gliomas and presumed CVA in dogs. VRU 52.1

A

When vasogenic edema develops - 3-5d after event

54
Q

What vessels make up the circle of willis?

A

Basilar artery - caudally
Internal carotid artery - caudal communicating arteries - lateral/caudal and anastomose with basilar artery
Internal carotid artery - rostral cerebral arteries - rostra portion

55
Q

What prouces a dark signal on T2* and T2 weighted image?

Comparative MRI findings between gliomas and presumed CVA in dogs. VRU 52.1

A

Hemorrhage, mineralization, gas, fibrous tissue, iron deposits

56
Q

Describe physics behind DWI and water motion?

Comparative MRI findings between gliomas and presumed CVA in dogs. VRU 52.1

A

Tw sequence with gardient pulses around 180 degree refocusing pulse

Static protons dephase and rephase - and appear as they would if symmetrical gradient had not been applied

Brownian motion results in phase change = loss onf DWI.

Acute infarction results in water trapping and reduced diffusion = increased signal on DWI

57
Q

How quickly can changes be seen on DWI/ADC maps?

Comparative MRI findings between gliomas and presumed CVA in dogs. VRU 52.1

A

DWi within 1 hour

ADC within 2 minutes

58
Q

What is internal vs external hydrocephalus?

MRI of intracranial malformations in dogs and cats. VRU 52.1

A

Internal hydrocephalus: Excess of CSf accumulated within the ventricular system

External hydrocephalus: excess of CSF in subarachnoid space, surrounding the brain

59
Q

What are two categories of hydrocephalus? What are examples of each?

MRI of intracranial malformations in dogs and cats. VRU 52.1

A

Obstructive - stenosis or blockage to CSF within the ventricular system, insufficient CSF resorption by arachnoid villi, or overproduction of CSF secondary to choroid plexus neoplasia/hyperplasia

Compensatory/Non-obstructive: following cerebral atrophy, degenerative encephalopathy

60
Q

What is the narrowest point within the ventricular system?

MRI of intracranial malformations in dogs and cats. VRU 52.1

A

Mesencephalic aqueduct - leads to obstructive hydrocephalus within the lateral and 3rd ventricles

61
Q

What is hydrancephaly?

MRI of intracranial malformations in dogs and cats. VRU 52.1

A

Abnormality in which the cerebrum is destroyed in utero and replaced by CSF filled cavity without residual neural parenchyma

62
Q

What is porencephaly?

MRI of intracranial malformations in dogs and cats. VRU 52.1

A

CSF-filled cavity within the brain that communicates with the ventricular system or subarachnoid space

63
Q

What is holoprosencephaly?

MRI of intracranial malformations in dogs and cats. VRU 52.1

A

failure of the forebrain to bifurcate normally into two discrete cerebral hemispheres

64
Q

What are 3 forms of holoprosencephaly?

MRI of intracranial malformations in dogs and cats. VRU 52.1

A

Alobar - complete lack of separation into two cerebral hemispheres - single lateral ventricle, all midline structures are fused, single cycloptic globe

Semi-lobar: rostral cerebral hemispheres fail to separate, but occipital lobes are distinct

Lobar: least severe, only most rostral and ventarl portions of the cerebral hemispheres are non-separated

65
Q

What other malformation is agenesis or dysgenesis of the corpus callosum associated with?

MRI of intracranial malformations in dogs and cats. VRU 52.1

A

holoprosencephaly

66
Q

What is lissencephaly?

What breed is this commonly seen in?

MRI of intracranial malformations in dogs and cats. VRU 52.1

A

Complete absence of gyri, or a reduction in the number of gyri

Lhasa apsos

67
Q

What is polymicrogyria?

What breed is this commonly seen in?

MRI of intracranial malformations in dogs and cats. VRU 52.1

A

Ecessive # of small, histologically anomalous gyri

Standard poodles

68
Q

What is the difference between a meningocele and meningoencephalocele?

MRI of intracranial malformations in dogs and cats. VRU 52.1

A

Meningoencephalocele - congenital protrusion of brain tissue covered by skin through a defect in the skull

Meningocele: fluid filled sac of meniges withou any brain parenchyma protruding through the skull

69
Q

What are intracranial arachnoid cysts usually due to?
Where are they most commonly found?
MRI of intracranial malformations in dogs and cats. VRU 52.1

A

Secondary to meningoencephalitis, trauma, subarachnoid hemorrhage

Most commonly seen in the caudal cranial fossa (quadrigeminal cistern)

70
Q

What are different imaging characteristics between epidermoid cysts and intra-arachnoid cysts?

MRI of intracranial malformations in dogs and cats. VRU 52.1

A

Both are hyperintense on T2, hypointense on T1

Epidermoid cyst - hyperintense on FLAIR
IAC - hypointense on FLAIR

71
Q

Differences between Dermoid and epidermoid cysts?

MRI of intracranial malformations in dogs and cats. VRU 52.1

A

Dermoid cysts will be heterogeneously hyperintense on T1 and T2 due to the high fat content

72
Q

What are common MR imaging features of CNS lymphoma?

MRI features of CNS lymphoma in dogs and cats VRU 53.1

A

Intra or extraparenchymal (brain - with mass effect), extraparenchymal only (spinal cord)
T2 hyperintense - indistinct margins
T1 hypointenese
FLAIR hyperintense - with perilesional hyperintensity
Strong contrast enhancement
Contrast enhancing meninges - around the abnormal area, or diffuse

73
Q

What are common MR imaging features of CNS lymphoma when compared to grey matter?

MRI features of CNS lymphoma in dogs and cats VRU 53.1

A

T2 - 50% iso/hyper
T1 - hypointense
FLAIR - most were isointense

74
Q

What are common MR imaging features of CNS lymphoma when compared to white matter?

MRI features of CNS lymphoma in dogs and cats VRU 53.1

A

T2 - hyperintense
T1 - hypointense
FLAIR - hyperintense

75
Q

What is prevalence of CNS lymphoma in dogs? cats?

MRI features of CNS lymphoma in dogs and cats VRU 53.1

A

Cats - #1 most common tumor in spinal cord, and 2nd most common IC tumor
Dogs - CNS lymphoma is 3rd most common secondary IC tumor (only accounts for 4% of total intracranial tumors)

76
Q

What are differential diagnoses for CNS lymphoma?
How may you differentiate between them?

MRI features of CNS lymphoma in dogs and cats VRU 53.1

A

Non-infectious/inflammatory - usually do not enhance, are mostly localized to the white matter
Meningioma - distinct margins, cyst/fluid
Oligo/astrocytomas - hemorrhage/necrosis, variable contrast enhancement
Histiocytic sarcoma - can look like anything, should always be a differential (intra/extra, dural tail, +/- contrast, singular/multifocal)
Metastatic tumors - can be associated with brain parenchyma r meninges, with associated edema and peripheral enhancement (rather than diffuse enhancement)

77
Q

When comparing the brain and spinal cord, what are the differences between location of lymphoma?

MRI features of CNS lymphoma in dogs and cats VRU 53.1

A

Brain - intraparenchymal, extraparenchymal, or both

Spinal cord - extraparenchymal only (dogs), can be intraparenchymal in cats

78
Q

What characteristics may a CNS lymphoma have on DWI?

MRI features of CNS lymphoma in dogs and cats VRU 53.1

A

Restricted diffusion - hyperintense on DW and hypointense on ADC images

79
Q

What is the ratio of the pituitary gland to brain area that makes a pituitary tumor likely?

CT and low field MRI of the pituitary gland in dogs with pituitary dependent hyperadrenocorticism JAVMA 235.4

A

> 0.31 - tumor

80
Q

What is the pituitary flush that is seen on dynamic CT?

MR?

CT and low field MRI of the pituitary gland in dogs with pituitary dependent hyperadrenocorticism JAVMA 235.4

A

Early enhancement of the neurohypophysis from the portal blood.

On MR - T1 - the vasopressin cells are hyperintense to the remaining pituitary parenchyma

81
Q

What other change, besides the increased pituitary: brain ratio that may indicate a tumor?

CT and low field MRI of the pituitary gland in dogs with pituitary dependent hyperadrenocorticism JAVMA 235.4

A

Displacement of the pituitary flush to the side (mass effect)

82
Q

What are differential diagnoses for pituitary masses?

A

adenomas
invasive adenomas
adenocarcinomas

Cross-sectional imaging characteristics of pituitary adenomas, invasive adenomas and adenocarcinomas in dogs: 33 cases JVIM 24

83
Q

How often do each type of pituitary tumor occur (adenoma, invasive adenoma, adenocarcinoma)?

Cross-sectional imaging characteristics of pituitary adenomas, invasive adenomas and adenocarcinomas in dogs: 33 cases JVIM 24

A

Adenoma - 61%
Invasive adenoma - 33%
Adenocarcinoma - 6%

84
Q

What are some clinical/imaging characteristics that can help distinguish between the types of pituitary masses?

Cross-sectional imaging characteristics of pituitary adenomas, invasive adenomas and adenocarcinomas in dogs: 33 cases JVIM 24

A

Invasive - dogs who are less than 7.7y of age
>1.9cm in height
Mineralization

85
Q

In the article:

Cross-sectional imaging characteristics of pituitary adenomas, invasive adenomas and adenocarcinomas in dogs: 33 cases JVIM 24

What was the prevalence of bony invasion?

A

0%

86
Q

Which type of pituitary mass had the worst clinical outcome?

Cross-sectional imaging characteristics of pituitary adenomas, invasive adenomas and adenocarcinomas in dogs: 33 cases JVIM 24

A

Invasive adenomas

87
Q

What is myelinolysis?

A

myelin loss secondary to rapid correction of hyponatremia

Myelinolysis after correction of hyponatremia in 2 dogs. JVIM 8.1

88
Q

What is difference between myelinolysis in humans and dogs?

Myelinolysis after correction of hyponatremia in 2 dogs. JVIM 8.1

A

Location of the lesions
Humans - almost all have pontine lesions. 50% will have pontine and extra-pontine lesions

Dogs - all have been extra-pontine - seen in the thalamus

89
Q

What is appearance of myelinolysis in the dog?

Myelinolysis after correction of hyponatremia in 2 dogs. JVIM 8.1

A

bilaterally symmetric, T2 hyperintensities in the central thalamic nuclei

No enhancement with contrast

These lesions get more apparent during treatment

90
Q

What is pathophysiology for why myelinolysis occurs?

Myelinolysis after correction of hyponatremia in 2 dogs. JVIM 8.1

A

Hyponatremia - causes movement of cations and amino acids out of the cell - including cerebrum.

When hyponatremia is rapidly corrected - this does not allow time for cells to take up these ions, and more fluid will rush out of the cells causing dehydration of the brain cells - and separation of the myelin from the oligodendrocytes

91
Q

What occurs with rapid correction of hypernatremia vs hyponatremia?

Myelinolysis after correction of hyponatremia in 2 dogs. JVIM 8.1

A

Hypernatremia - cerebral edema - swelling of cells

Hyponatremia - myelinolysis - dehydration of cells

92
Q

What lesions occur on MR in hypoglycemic patients?

A

Crescent shaped T2 and T1 hyperintense lesions in the caudate nucleus. On T1 images, the central region is hypointense.

No contrast enhancement

Insulinoma with basal ganglion involvement detected by MRI in a dog J Vet Med Sci 71.5

93
Q

What is the difference between before and after MRI for dogs with hypoglycemia?

Insulinoma with basal ganglion involvement detected by MRI in a dog J Vet Med Sci 71.5

A

Before: Crescent shaped T2 and T1 hyperintense lesions in the caudate nucleus. On T1 images, the central region is hypointense.
No contrast enhancement

After: T2/FLAIR remains hyperintense, T1 - no longer hyperintense, but central hypointense portions remains unchanged

94
Q

Described anatomy of quadrigeminal cistern and the closely associated ventricular system

MDCT and low-field MRI anatomy of the quadrigeminal cistern and characterization of supracollicular fluid accumulations in dogs VRU 57.3

A

3rd ventricle, aqueduct and quadrigeminal cistern are all separated by a thin ST membrane that is isoechoic/attenuating to surrounding soft tissues - best seen on sagittal images

QC - thin, linear, fluid accumulation dorsal to quadrigeminal plate (the mermaid arm) and rostral to the cerebellum

95
Q

Described appearance of quadrigeminal cistern ons agittal/dorsal view

MDCT and low-field MRI anatomy of the quadrigeminal cistern and characterization of supracollicular fluid accumulations in dogs VRU 57.3

A

Sagittal : QC - thin, linear, fluid accumulation dorsal to quadrigeminal plate (the mermaid arm) and rostral to the cerebellum

Dorsal images - H-shaped fluid accumulation caudal to interthalamic adhesion and cranial to cerebellum

96
Q

What are the 3 categories of supracollicular fluid accumulation?

Which was most common

MDCT and low-field MRI anatomy of the quadrigeminal cistern and characterization of supracollicular fluid accumulations in dogs VRU 57.3

A 
#1 (most common) - SFA-III - diverticulum/dilation of the 3rd ventricle
#2 - SFA-III + QC - dilation of both third ventricle and QC
#3 - SFA-QC - dilation of only the quadrigeminal cistern
97
Q

What breeds are predisposed to Supracollicular fluid accumulation?

MDCT and low-field MRI anatomy of the quadrigeminal cistern and characterization of supracollicular fluid accumulations in dogs VRU 57.3

A

Shih-tzu
Maltese
Yorkies

98
Q

What type of cerebellar compression did each category of SFA cause?

MDCT and low-field MRI anatomy of the quadrigeminal cistern and characterization of supracollicular fluid accumulations in dogs VRU 57.3

A

SFA-III - cranial compression of the cerebellum

SFA-QC - dorsoventral compression

Radiology Journal Club (19 decks)

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