Diagnostic imaging Flashcards
Name the myelographic pattern
extradural/extramedullary mass lesion at C6-7
Differential diagnoses for an extradural/extramedullary lesion?
IVD extrusion
dyscospondilitis
epidural abscess
epidural haemorrhage
vertebral neoplasia (primary and metastatic)
DDs for an intradural/extramedullary lesion?
meningioma
nerve sheet tumour
nephroblastoma
DDs for an intramedullary lesion
neurectodermal neoplasia
metastatic neoplasia
granulomatous inflammation
spinal cord oedema (eg. with FCE)
Name the myelographic pattern
extradural/extramedullary compression from dorsal and ventral C5-6
(Cervical myelogram of a 7-year-old doberman pinscher with an extradural mass lesion causing a dorsal and ventral compression of the spinal cord at the C5–C6 articulation. The lesion is a protrusion of the annulus fibrosis of the intervertebral disc and a proliferation of the articular processes and joint capsules of the synovial joints, the yellow ligament, or both.)
Name the myelographic pattern
intradular/extramedullary
Thoracic myelogram of a 5-month-old Labrador retriever with an intradural-extraparenchymal mass lesion compressing the spinal cord at the level of the T12 vertebra. The lesion is a nephroblastoma growing in the subarachnoid space. Note the cupping shape of the contrast as it attempts to pass by the neoplasm that obstructs the subarachnoid space)
Name the myelographic pattern
intradural-extramedullary
Cervical myelogram of a 6-year-old Labrador retriever with an intradural-extraparenchymal mass lesion compressing and displacing the spinal cord at the level of the C6 vertebra. The mass lesion is a nerve sheath neoplasm involving the C7 spinal roots and nerve on one side. Note the numerous cup shapes made by the contrast as it surrounds the neoplasm that is growing in the subarachnoid space.
Name the myelographic pattern
intramedullary
Lumbar myelogram of a 7-year-old basset hound with an intraparenchymal mass lesion at the level of the L3 vertebra. The contrast lines deviate to the sides of the vertebral foramen in both this lateral view and in the dorsal view. The mass lesion was in the spinal cord parenchyma; at autopsy, it was identified as a hemangioendothelioma.
What is shown in this MRI image of a 10-year-old female spayed mixed-breed dog that presented for obtundation and tetraparesis?
transverse T2-weighted image at the level of the medulla and tympanic cavities. There is marked dilation of the fourth ventricle (asterisk) with expansion of the lateral recesses (arrows). Note the choroid plexus within the lateral recesses of the fourth ventricle (open arrowheads). Between the lateral recesses and the main portion of the fourth ventricle are the cerebellar peduncles.
Which part of the ventricular system is shown dilated in this image of a cat with obstructive hydrocefalus due to FIP infection?
olfactory bulbs
Obstructive hydrocephalus in a 2-year-old cat
subsequently diagnosed with feline infectious peritonitis.
This dorsal T2W image shows bilaterally symmetric dilation
of the recesses of the olfactory bulbs (arrows) along with
generalized ventriculomegaly
What is shown in this FLAIR MRI image of a dog with cryptococcal meningitis?
dilation of the lateral ventricles and periventricular FLAIR hyperintensities
Obstructive hydrocephalus in a 3-year-old Bouvier
des Flandres with cryptococcal meningitis. On this transverse
T2-FLAIR image, CSF in the ventricles is black due to
suppression of fluid signal (asterisk). There is bilateral
periventricular hyperintensity consistent with transependymal
migration of CSF, which was most severe in the rostral part of
the brain in this patient (arrow)
Name MRI findings helpful in discriminating clinically relevant from incidental ventriculomegaly
- A ventricle/brain index >0.6 on dorsal plane images.
The ventricle/brain index is evaluated on dorsal T2
images and defined as the maximum continuous distance
between the internal borders of the ventricles
divided by the maximum width of the brain parenchyma
in the same image. - Elevation of the corpus callosum and dorso ventral
flattening of the interthalamic adhesion, best seen on
sagittal plane images. - Periventricular edema
- Dilation of the olfactory recesses
- Thinning of the cortical sulci and/or sub arachnoid
space. - Disruption of the internal capsule adjacent to the
caudate nucleus.
Imaging diagnosis? 10 MO mix breed dog with seizures
Ethmoidal meningoencephalocele
This sagittal T2W image demonstrates
absence of part of the cribriform plate and herniation of the
olfactory bulb into the caudal nasal cavity (arrowhead), with
concurrent formation of a cyst-like lesion in the most rostral
aspect (arrow).
What is seen on this sagittal MRI image of a young Miniature Schnauzer presenting with hypodipsia?
dysgenesis of the corpus callosum
Imaging diagnosis? 1 YO Chinese Crested dog presenting with abnormal mentation, behavioral abnormalities, visual
problems, and seizures.
Lissencephaly
* This disorder of cortical neuronal migration is characterized
by paucity, absence, and/or hypoplasia of cerebral
gyri (pachygyria) and thickening of the cerebral
cortex
* The disease has been reported in dogs and cats and it
appears to be hereditary in Lhasa Apsos.
* Clinical signs can range from mild to severe and include
abnormal mentation, behavioral abnormalities, visual
problems, and seizures. Affected animals present from
less than 1 to several years of age.
* MRI findings include:
* A smooth cerebral surface and a thick neocortex with
absence of the corona radiata
* Less commonly, concurrent anomalies such as cerebellar
hypoplasia, corpus callosum abnormalities,
ventriculomegaly, or arachnoid cysts.
Imaging diagnosis and typical breed of dog?
Polymicrogyria
- This is a disorder of cerebrocortical development resulting
in an increased number of small, disorganized gyri in
the dorsal and lateral cerebral cortex. - It has been reported in Standard Poodles, in which a
hereditary basis is suspected.63,64 - Affected dogs present with cortical blindness and other
neurologic abnormalities including gait and behavioral
changes. Age at presentation ranges from 7 weeks to 5 years. - MRI findings include:
- Increased numbers of disorganized shallow gyri in
the occipital lobes, most easily visualized on dorsal
plane T2W images ( - Less common MRI findings include ventriculomegaly/
hydrocephalus63 and thinning of the subcortical white
matter in the occipital lobes.
Imaging diagnosis?
4 YO cat presenting with new onset of seizures
Dyke–Davidoff–Masson-like syndrome
Dyke–Davidoff–Masson-like syndrome is a syndrome
described in people with intrauterine or early childhood
loss of unilateral brain parenchyma and subsequent
asymmetric changes to the cranium.
* A few cases of this condition have been reported in a cats presented with new-onset seizures.
* MRI findings include:
* Hypoplasia/partial absence of a cerebral hemisphere.
* Changes in the overlying cranium including hyperostosis
and expansion of the diploic space and ventriculomegaly
MRI diagnosis?
6 MO West Highland White Terrier with L circling and behaviour abnormalities.
Hydranencephaly
- In hydranencephaly, there is near complete destruction
and/or lack of development of the neocortex due to a
destructive process occurring in utero, typically associated
with viral infection (e.g., panleukopenia), although
other etiologies including hypoperfusion/hypoxia have
been proposed. - Unless other brain lesions are present, clinical signs reflect
the loss of cerebral cortex (circling, behavioral abnormalities,
seizures, lethargy, blindness) while gait is maintained. - Age at presentation in naturally affected dogs and cats
ranges from 8 weeks to 13 months. - MRI findings include:
- Uni- or bilateral reduction of size of the cerebral cortex
to a thin mantle surrounding a large fluid-filled cavity
contiguous with the lateral ventricle - Total loss of parietal and temporal lobes and partial
loss of frontal and occipital lobes on the affected side
are reported in dogs.
MRI diagnosis?
5 YO Old English Sheepdog with seizures.
Porencephaly
* In porencephaly, cystic cavities are present in the cerebrum due to cell destruction or failure of development.
* Affected animals may be asymptomatic, present with
clinical signs related to the affected area of the brain
including seizures, or, surprisingly, may show neurologic signs not normally localized to the forebrain such as nystagmus. Clinical signs may not become apparent until later in life, and age at presentation reported in the
literature ranges from 12 weeks to 7 years.
* MRI findings include:
* Cerebral cavities of variable size with MRI signal
identical to CSF
* Lesions may be unilateral or bilateral, single or multiple, and are commonly wedge shaped.
* Cavities may communicate with the ventricles or subarachnoid space.
Radiografic diagnosis?
10-year-old male Gordon setter, who experienced 1 month of progressive gait abnormality in the right pelvic limb showing “skipping gait” of the RPL
Soft tissue mass ventral to the L6, L7
The skipping-type gait, which is characteristic of a sciatic nerve dysfunction and is caused by the brisk, unopposed flexion of the hip. Weight support is normal, but during weight support the tarsus is overflexed, and the hind paw is occasionally placed on its dorsal surface. Remember the course of the nerves that form the sciatic nerve along the medial side of the ilium to cross the body at the greater ischiatic notch.
Dysfunction of which cranial nerve is most likely here, based on the findings pointed to by the arrows?
Sagittal T2-weighted image of an 11-year-old mixed-breed dog with a nerve sheath neoplasm arising from cranial nerve V on the left side. Note the atrophy and T2 hyperintensity of the rostral belly (white arrow) in contrast to the caudal belly (black arrow) of the digastricus muscle. Recall the rostral belly of the digastricus muscle is innervated by cranial nerve V, whereas the caudal belly is innervated by cranial nerve VII. The myotendinous junction demarks the separation between the rostral and caudal bellies of the digastricus muscle (arrowhead). Additionally, there is effusion in the tympanic cavity (open arrow) secondary to paralysis of the tensor veli palatini muscle. There also is severe atrophy of the temporalis muscle.
