Diagnostic imaging Flashcards
Name the myelographic pattern
extradural/extramedullary mass lesion at C6-7
Differential diagnoses for an extradural/extramedullary lesion?
- IVD extrusion
- discospondylitis
- 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 hydrocephalus due to FIP infection?
olfactory recesses within the 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.
- Affected dogs present with cortical blindness and otherneurologic 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/hydrocephalus 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
Which MRI signs are typical for canine Chiari-like malformation?
MRI features of the condition are typically best appreciated on T2W sagittal images, and include:
- Crowding of the caudal fossa with indentation of the caudal margin of the cerebellum by the occipital bone, causing the caudal margin of the cerebellum to become concave rather than flattened or convex
- Attenuation of the subarachnoid space caudal to the cerebellum and at the foramen magnum (impaction)
- Note that cerebellar indentation and impaction have a prevalence of 37%–51% and 16%–28%, respectively, in non-Cavalier King Charles Spaniels without signs of Chiari-like malformation, and therefore may not in isolation constitute accurate MRI indicators of this anomaly.
- Herniation of the cerebellar vermis into or through the foramen magnum, which is exacerbated by neck flexion. The degree of cerebellar herniation is not associated with the presence or absence of concurrent syringomyelia
- ‘Kinking’ of the medulla or cranial cervical spinal cord at the craniocervical junction.
- Secondary syringomyelia, identified as a linear T2 hyperintensity of variable width oriented along the long axis of the cord.
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.
pathology of which muscle is shown in the image?
Which nerve innervates this muscle?
Caudal belly of the digastricus -> CN VII
(the rostral belly of the digastricus is normal -> CN V mandibular branch)
Dysfunction of which nerve is shown here? Which muscles are atrophied?
Craniocaudal view of the larynx of a horse with a left-side paralysis that resulted in severe denervation atrophy of all the intrinsic muscles of the larynx except for the cricothyroid. This is especially evident here in the cricoarytenoideus dorsalis muscle
Most likely Dx?
Sagittal T2-weighted magnetic resonance image of the neck and cranial thorax of a 7-year-old male Shetland sheepdog that became tetraparetic after being attacked by a larger dog, grasped by the neck, and shaken.
ANNPE
- loss of hyperintensity of the nucleus pulposus of the intervertebral disc between the C6 and C7 vertebral bodies
- interruption of the adjacent subarachnoid space but without significant evidence of extradural extruded intervertebral disc
- hyperintensity of the adjacent spinal cord parenchyma (sugg. of oedema or ischemia or necrosis)
What is shown in the image? 5 YO thoroughbred with a history of 3 weeks of ataxia of all 4 limbs
Lateral cervical radiograph showing degenerative joint disease of the synovial joints at the C5–C6 and C6–C7 articulations.
What is shown in the image? 6 YO warmblood horse with a history of 1 week of ataxia of all 4 limbs
Lateral radiograph of the C6–C7 articulation
extensive degenerative joint disease of the synovial joints at the articular processes.
Which CN is affected (arrow)?
What is shown with the asterix?
6-year-old male neutered Beagle presented with internal ophthalmoplegia and external ophthalmoparesis of the right eye
There is marked enlargement of the right oculomotor nerve with isointensity
on T2W (arrow; A), hypointensity on FLAIR (arrow; B), and isointensity on T1W precontrast (arrow; C) with marked focal homogeneous enhancement
following contrast administration (arrow; D).
Calculating the intravertebral and intervertebral ratio of the cervical spine in horses?
The intravertebral sagittal ratio is calculated by dividing the minimum height of the
spinal canal (dotted line) by the maximum height of the cranial aspect of the same vertebral
body (double arrowed line). The intervertebral ratio is calculated by dividing the minimum
intervertebral distance (solid line) by the maximum height of the cranial aspect of the
caudal vertebral body (double arrowed line).
1) intravertebral cut off: Rush Moore et al.
recommended using a cut off value of 0.52 for C3-4, C4-5, C5-6, and a cut off value of 0.56 for C6-C7 to determine sites of possible spinal cord compression
2) intervertebral: Hahn et al.
recommended using a cut off value of 0.485 for all sites from C3-C7.
Calculating the dorsal column and dural diameter measurements in equine cervical spine X-ray myelography
50% reduction in the height of the dorsal contrast column as compared with the height
of the dorsal contrast column in the cranial vertebra and a 20% reduction in the total
dural diameter of the contrast column as compared with the total dural diameter of the
contrast column in the cranial vertebra
HU units of acute haemorrhage in non-contrast CT?
acute hemorrhage (40–60 HU)
compared to gray (39 HU)
or white (32 HU) matter
Within hours of the onset of hemorrhage, attenuation of the hematoma rapidly increases up to 60–80 HU due to the formation of a fibrin and globulin meshwork, and remain visible on NCT for approximately 1 week
Difference between SWI and T*GRE?
Currently, T2 -GRE is the most commonly used sequence for evaluating hemorrhage in dogs and has been demonstrated to be the most accurate of all MR pulse sequences and more accurate than CT in dog models in predicting the extent of hemorrhage. T2 -GRE sequences are not 100% sensitive for the detection of all stages of intracranial hemorrhage because after erythrolysis, methemoglobin moves into the extracellular space and becomes homogeneously distributed in plasma. This means that the magnetic field within the voxel also becomes homogeneous, which causes loss of susceptibility artifact. Furthermore,
the artifact distortion is directly proportional to the magnetic field strength, so the size of hemorrhage can vary between scanners.
Subsequently, SWI has been demonstrated to be more reliable for cerebral microbleeds than T2 -GRE
Causes of T2 shine-through?
- vasogenic oedema,
- pyogenic abscesses,
- highly cellular tumors,
- status epilepticus,
- global ischemia,
Reversal of DWI and ADC abnormalities - when does it appear?
Over time, the appearance of the DWI and ADC
abnormalities reverse as the stroke moves into a subacute phase within 24 h to 5 days. This progression makes it possible to estimate the age of the infarct core to some degree
Percentage
