MRI features of CNS lymphoma in dogs and cats

The magnetic resonance (MR) imaging features of central nervous system lymphoma in eight dogs and four cats are described. Intracranial lesions affected the rostrotentorial structures in six dogs and caudotentorial structures in two cats. Lesions affected the spinal cord in two dogs and in two cats. One dog and one cat with intracranial lymphoma had signs of local extracranial extension and lymphadenopathy. Lesions were considered extraparenchymal in four dogs and three cats, intraparenchymal in two dogs and one cat, and appeared to have both intra- and extraparenchymal components in two dogs. All lesions were hyperintense in T2-weighted images when compared to white matter, most were hypointense in T1-weighted images (7/12), and most were hyperintense in fluid-attenuated inversion recovery (FLAIR) images (5/9). When compared to grey matter, these lesions appear either isointense (5/12) or hyperintense (7/12) on T2-weighted images, half of them were hypointense in T1-weighted images (6/12), and most were isointense in FLAIR images (7/9). Lesion margins were usually indistinct in T2-weighted images (10/12) and had perilesional hyperintensity in FLAIR images (7/9). The majority of lesions (10/12) had abnormal meninges around the lesion and half (6/12) had generalized contrast enhancement. Mass effect was evident in all lesions. Although not specific, when combined with the history and neurologic signs, MR features aid presumptive diagnosis that should be confirmed by cytology or histopathology.     

Characteristics of magnetic resonance images of granulomatous meningoencephalomyelitis in 11 dogs

The characteristics of magnetic resonance imaging (mri) of the brains and spinal cords of 11 dogs with histologically confirmed granulomatous meningoencephalomyelitis (gme) were determined. The lesions were in the brain of eight of the dogs, in the brain and spinal cord of two, and in the spinal cord alone in one dog. A single lesion was present in four of the dogs and multiple lesions were found in six. In one dog with intracranial signs, no visible lesions could be detected on mri. No meningeal enhancement was detected in T1-weighted images post-contrast, or in fluid attenuation inversion recovery (flair) images, but there were histological lesions in the meninges in nine of the dogs. The T2-weighted images and flair sequences were characterised in all cases by hyperintensity, whereas the signal intensity of the lesions on T1-weighted images was variable. After the administration of paramagnetic contrast, some of the lesions showed no enhancement, but others showed marked patterns of enhancement. The lesions in 10 of the dogs were easily identifiable by mri and the images had several unifying characteristics, but they could not be considered disease-specific.     

Intramedullary epidermoid cyst in the thoracic spine of a dog

A 5 yr old female spayed mastiff was evaluated for a 3-4 mo history of paraparesis and 3 days of acutely worse paraparesis and incontinence. On magnetic resonance imaging, a spinal cord lesion was present at the ninth thoracic vertebra. The lesion was hyperintense on T2-weighted images (T2-W), and a hyperintense rim was present on T1-weighted postcontrast images. Histologic examination showed a cystic mass lined by squamous epithelial cells. Histopathologic diagnosis was an intramedullary epidermoid spinal cyst. Epidermoid cyst should be a differential diagnosis in young dogs with a myelopathy and an intramedullary spinal cord lesion on magnetic resonance imaging examination.     

MRI of a split cord malformation in a german shepherd dog

A 9 yr old spayed female German shepherd dog was referred for MRI of the thoracic and lumbar spine because she had clinical signs of chronic neurogenic bladder dysfunction of an unknown cause. Transverse T2-weighted images identified a type II split cord malformation (i.e., diastematomyelia) in the thoracic spine. Split cord malformations are forms of spinal dysraphism where the abnormal development of spinal cord results in sagittal splitting of a portion of the cord into two hemicords. The location of the lesion in the thoracic spine was consistent with the dog's clinical signs of an upper motor neuron bladder. Split cord malformations that occur in humans have similar MRI characteristics and can result in similar clinical signs as those identified in the dog described in this report.     

MRI characteristics of suspected acute spinal cord infarction in two cats, and a review of the literature

A 10-year-old neutered male Persian cat and a 4-year-old spayed female domestic shorthair (DSH) cat were evaluated for acute-onset severe lateralising tetraparesis and hemiplegia, respectively. Both cats also had left-sided Horner's syndrome. Neurological examination of the cats localised the lesion to cranial to C5 in the Persian and the left cervical intumescence (C6-T2) in the DSH. Physical examinations were otherwise generally unremarkable. Routine laboratory tests and spinal radiography were normal for the Persian cat and were not performed for the DSH cat. A cerebrospinal fluid (CSF) tap was attempted for the Persian cat but aborted because of gross blood contamination, and was not performed for the DSH cat. Magnetic resonance imaging (MRI) of the Persian cat revealed a lesion within the spinal parenchyma at segments C1 to C3 (slightly more left-sided) which was iso- to hypointense on T1-weighted scans and hyperintense on T2-weighted scans, and which enhanced slightly with gadolinium. MRI of the DSH cat revealed a lesion within the spinal parenchyma at segment C7 (predominantly left-sided) which was hypointense on T1-weighted scans and hyperintense on T2-weighted gradient echo scans. Contrast was not administered. The MRI findings in both cases were highly suggestive of acute spinal cord infarction, based upon comparison to human cases. Both cats made full neurological recoveries with supportive treatment only. This paper describes two cases of suspected acute spinal cord infarction in the cat, demonstrates the potential diagnostic value of MRI, and discusses the clinical syndrome of this condition with a brief review of published cases.     

Brain and spinal cord haemorrhages associated with Angiostrongylus vasorum infection in four dogs

Multifocal haemorrhages associated with Angiostrongylus vasorum infection were observed in the central nervous system of four dogs with neurological signs including depression, seizures, spinal pain and paresis. In magnetic resonance images the majority of the lesions were isointense or slightly hyperintense in T1-weighted images, hyperintense in T2-weighted images and hypointense in T2*-weighted (gradient echo) images, compatible with haemorrhages more than seven days old. Lesions were found in the brain of three of the dogs and in the spinal cord of two. The cerebrospinal fluid contained high concentrations of protein and evidence of erythrophagia. All the dogs had coagulopathy and pulmonary haemorrhage of varying severity. A vasorum larvae were detected in the faeces of each of the dogs. Neural A vasorum was confirmed at postmortem examination in two dogs.     

Magnetic resonance imaging features of spinal epidural empyema in five dogs.

Spinal epidural empyema is defined an accumulation of purulent material in the epidural space of the vertebral canal. Spinal epidural empyema should be considered as a differential diagnosis in dogs with pyrexia, spinal pain, and rapidly progressing myelopathy. Magnetic resonance (MR) imaging is the imaging test of choice in humans. Here, we describe the MR imaging features of five dogs with confirmed spinal epidural empyema. The epidural lesions appeared as high or mixed signal masses in T2-weighted (T2W) images. Increased signal within the spinal cord gray matter at the site of the lesion was detected in T2W images in all dogs. Two patterns of enhancement were detected on postcontrast T1-weighted (T1W) images. Mild to moderate peripheral enhancement was seen in three dogs and a diffuse pattern of enhancement was seen in one. Discospondylitis was identified in three dogs on T1W postcontrast images. Decompressive spinal surgery was performed in all dogs. Bacteria isolated from the abnormal epidural tissue were Enterobacter cloacae, coagulase-positive Staphylococci, Pasteurella multocida, and Escherichia coli. In one dog bacteria were not isolated. These MR imaging features, along with appropriate clinical signs, can allow prompt diagnosis and appropriate treatment planning.     

MAGNETIC RESONANCE IMAGING AND PATHOLOGIC FINDINGS ASSOCIATED WITH NECROTIZING ENCEPHALITIS IN TWO YORKSHIRE TERRIERS

Two young adult Yorkshire terriers had neurologic signs consistent with forebrain and brainstem involvement or forebrain involvement alone. On magnetic resonance imaging studies there were asymmetric bilateral lesions mainly in the cerebral cortex, and in the diencephalon. These areas were hyperintense on T2-weighted and FLAIR images, but hypointense or isointense on T1-weighted images. Lesions had a varying degree of contrast enhancement. Areas which were isointense on T1-weighted images had no contrast enhancement or only foci of contrast enhancement. Lesions with hypointensity in T1-weighted images had no enhancement or more frequently ring-like enhancement around the lesion. Necrotizing encephalitis was confirmed pathohistologically in both dogs. The degree of contrast enhancement appeared to be related to the degree of lymphohistiocytic inflammation on histologic examination.     

METRIZAMIDE MYELOGRAPHY IN FIVE DOGS AND TWO CATS WITH SUSPECTED SPINAL CORD NEOPLASMS

Metrizamide myelography was used in five dogs and two cats with signs of spinal cord disease. The history, clinical signs, cerebrospinal fluid examination, and myelography supported a presumptive diagnosis of spinal cord neoplasia in all seven animals. Myelography demonstrated a deviation of the subarachnoid space in each of them. Five of the animals had an expansile intramedullary spinal cord lesion causing thinning and peripheral deviation of the subarachnoid space. Two had extramedullary lesions causing a central deviation of the subarachnoid space. Spinal cord tumors in six of the seven animals were confirmed by necropsy or surgical excision and histopathologic examination. In the seventh animal, a spinal cord fungal grapuloma was diagnosed by necropsy.     

QUANTITATIVE MAGNETIC RESONANCE IMAGING OF THE NORMAL FELINE CRANIAL ABDOMEN

Magnetic resonance images of the cranial abdomen were acquired from 15 clinically normal cats. All cats had T1-weighted images, 8 cats had T2-images made and 7 cats had T1-weighted post Gd-DTPA images acquired. Signal intensity measurements for T1, T2, and T1 post contrast sequences were calculated for liver, spleen, gallbladder, renal cortex, renal medulla, pancreas, epaxial muscles, and peritoneal fat. On T1-weighted images the epaxial muscle had the lowest signal intensity, followed by renal medulla, spleen, renal cortex, pancreas, liver and fat, respectively. On T2-weighted images, epaxial muscle had the lowest signal intensity followed by liver, spleen, fat, and gallbladder lumen. Calculations of specific organ percent enhancement following contrast medium administration were made and compared with that reported in humans. A brief review of the potential clinical uses of MR in cats is presented.     

Cervical vertebral malformation-malarticulation syndrome in the Bernese mountain dog: clinical and magnetic resonance imaging features

O bjectives : To describe the clinical and magnetic resonance imaging features of cervical vertebral malformation-malarticulation in Bernese mountain dogs.
M ethods : Seven Bernese mountain dogs (four males and three females) were diagnosed with cervical vertebral malformation-malarticulation by magnetic resonance imaging. The following data were evaluated retrospectively: (1) abnormalities of the cervical vertebral column and spinal cord, (2) spinal cord compression, (3) intervertebral disc degeneration and herniation, (4) severity of clinical signs pretreatment and after treatment, (5) type of treatment and (6) outcome.
R esults : Spin echo T1-weighted and T2-weighted images disclosed multi-level, extradural compressive spinal cord lesions (ventral, dorsolateral or both) spanning from intervertebral disc spaces C3-4 to C6-7. In all seven dogs, T2-weighted images disclosed one or more intramedullary hyperintensities associated with extradural spinal cord compression. Surgery was performed in five dogs. Two dogs were managed medically. The prognosis for surgical or conservative management in Bernese mountain dogs was similar to cervical vertebral malformation-malarticulation in other breeds.
C linical S ignificance : Cervical vertebral malformation-malarticulation is an important differential diagnosis for young to middle-aged Bernese mountain dogs with a C1-5 or C6-T2 neuroanatomic localisation. Dorsolateral spinal cord compression associated with articular process hypertrophy was the most common feature of cervical vertebral malformation-malarticulation in the seven Bernese mountain dogs evaluated.     

Suspected fibrocartilaginous embolism in a cat

A 12-year-old cat was presented to the University of Queensland's Small Animal Teaching Hospital with a 1-day history of left hemiparesis of acute onset, with no evidence of trauma or toxin exposure. Neurological examination findings were consistent with a lesion in the caudal left cervical spinal cord (C6 to C8), which was non-painful and had not progressed since the onset of clinical signs. No other abnormalities were found, although myelography showed a mild swelling involving the caudal cervical and cranial thoracic spinal segments. A diagnosis of suspected fibrocartilaginous embolism was made on the basis of the history, clinical presentation and diagnostic tests results, making this case the first report of a suspected fibrocartilaginous embolism in a cat that returned to normal function.     

Fibrocartilaginous emboli in a tayra (Eira barbara): a case report.

An 8-yr-old male tayra (Eira barbara) was presented with acute onset of pelvic limb paralysis. Radiography was unremarkable. Neurologic examination showed signs consistent with an intramedullary lesion between the second thoracic and fifth lumbar spinal cord segments. The animal's condition did not improve after 4 days of aggressive glucocorticoid therapy, and euthanasia was performed. Histologic examination of the spinal cord showed amorphous emboli suggestive of cartilaginous fragments within spinal veins. A diagnosis of fibrocartilaginous emboli was made, the first known case in a mustelid.     

Fibrocartilaginous embolism in a cat

A nine-year-old cat was presented with a history of an acute onset of paraplegia. On the basis of the neurological examination, the lesion was localised between the fourth lumbar and third sacral segments (L4 to S3) of the spinal cord. Investigations included radiography, myelography, cerebrospinal fluid analysis, routine haematology and biochemistry, feline leukaemia virus testing and urinalysis. A definitive diagnosis was not achieved and the cat was euthanased 12 days after presentation. Post mortem examination revealed infarction of the spinal cord secondary to fibrocartilaginous embolisation. This is the first reported case of fibrocartilaginous embolism in the cat in the UK.     

Prognostic value of magnetic resonance imaging in dogs with paraplegia caused by thoracolumbar intervertebral disk extrusion: 77 cases (2000-2003)

OBJECTIVE: To determine whether magnetic resonance imaging findings in dogs with paraplegia caused by thoracolumbar intervertebral disk extrusion were predictive of clinical outcome. DESIGN: Retrospective case series. ANIMALS: 77 dogs. PROCEDURE: Medical records and magnetic resonance images were reviewed; clinical outcome was classified as successful (regained ability to walk with no more than mild neurologic deficits) or unsuccessful (severe neurologic deficits persisted). The prognostic value of magnetic resonance imaging was compared with prognostic value of deep pain perception, duration of clinical signs, and rate of onset of clinical signs. RESULT: 33 (43%) dogs had areas of hyperintensity of the spinal cord greater than or equal to the length of the L2 vertebral body on T2-weighted magnetic resonance images. All 44 dogs without areas of hyperintensity on T2-weighted images had a successful outcome, but only 18 of the 33 (55%) dogs with an area of hyperintensity did. Only 5 of 16 dogs with an area of hyperintensity that had also lost deep pain perception had a successful outcome. The odds ratio for an unsuccessful outcome for a dog with an area of hyperintensity (29.87) was higher than the odds ratio for a dog that had lost deep pain perception (5.24). Duration and rate of onset of clinical signs were not associated with clinical outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Findings suggest that results of magnetic resonance imaging can be used to predict clinical outcome in dogs with paraplegia caused by intervertebral disk extrusion.     

MAGNETIC RESONANCE IMAGING FEATURES OF TUMORS OF THE SPINE AND SPINAL CORD IN DOGS

Twenty-one dogs with confirmed tumors of the spinal cord or paraspinal tissues were imaged with magnetic resonance (MR) imaging. Anatomical location, location in relation to the dura and the medulla (spinal cord), and bone infiltration were assessed on the MR images and compared to findings at surgery or necropsy. Localization of tumors in the intradural-extramedullary compartment was not always possible. Bone infiltration was correctly assessed in all but one dog, and the anatomical locations involved were accurately determined in all dogs. Sagittal T2-weighted images were helpful to determine the anatomical location. Transverse T1-weighted images pre and post Gd-DTPA administration were helpful for additional localization and definition of tumor extension.     

Association of spinal cord compression seen on magnetic resonance imaging with clinical outcome in 67 dogs with thoracolumbar intervertebral disc extrusion

OBJECTIVES: To determine whether there is an association between the degree of transverse spinal cord compression detected by magnetic resonance imaging following thoracolumbar Hansen type 1 intervertebral disc disease in dogs and their presenting and postsurgical neurological status. METHODS: Medical records of 67 dogs with surgically confirmed Hansen type 1 intervertebral disc disease (2000 to 2004) were reviewed to obtain the rate of onset of disease, duration of clinical signs and presurgical and postsurgical neurological grade. Percentage of spinal cord compression was determined on transverse T2-weighted magnetic resonance images. Linear regression was used to examine the association between spinal cord compression and each of the above variables. Chi-squared tests were used to examine associations among postsurgical outcome and presurgical variables. RESULTS: Eighty-five per cent (57 of 67) of dogs were chondrodystrophoid. Mean spinal cord compression was 53 per cent (sd=219.7, range 14.3 to 84.9 per cent). There was no association between the degree of spinal cord compression and the neurological grade at presentation, rate of onset of disease, duration of clinical signs or postsurgical outcome, with no difference between chondrodystrophoid and non-chondrodystrophoid dogs. CLINICAL SIGNIFICANCE: The degree of spinal cord compression documented with magnetic resonance imaging in dogs with thoracolumbar Hansen type 1 intervertebral disc disease was not associated with the severity of neurological signs and was not a prognostic indicator in this study.     

Magnetic resonance imaging findings and clinical associations in 52 dogs with suspected ischemic myelopathy

BACKGROUND: The magnetic resonance imaging (MRI) features of ischemic myelopathy have been described in the human literature and in a small number of cases in the veterinary literature. HYPOTHESIS: The aims of this study were to identify associations among MRI findings, timing of imaging, and presenting neurologic deficits in a large series of dogs with a presumptive diagnosis of ischemic myelopathy. ANIMALS AND METHODS: The medical records and MR images of dogs with a presumptive diagnosis of ischemic myelopathy (2000-2006) were reviewed retrospectively. Inclusion criteria were acute onset of nonprogressive and nonpainful myelopathy, 1.5-tesla MRI of the spine performed within 7 days of onset, and complete medical records and follow-up information. Presumptive diagnosis was based on history, as well as clinical, MRI, and cerebrospinal fluid (CSF) findings. The extent of the lesion on MRI was assessed as the following: (1) the ratio between the length of the hyperintense area on sagittal T2-weighted images and the length of C6 or L2 vertebral body, and (2) the maximal cross-sectional area of the hyperintense area on transverse T2-weighted images as a percentage of cross-sectional area of the spinal cord. RESULTS: Fifty-two dogs met the inclusion criteria. MRI findings were abnormal in 41 dogs and normal in 11 dogs. The presence of MRI abnormalities was not significantly associated with the timing of imaging (P = .3) but was associated with ambulatory status on presentation (P = .04). Severity of signs on presentation was associated with extent of the lesion on MRI (P = .02). CONCLUSION AND CLINICAL IMPORTANCE: The severity of signs on presentation is associated with the presence and the extent of the lesion on MRI.     

COMPARISON OF MAGNETIC RESONANCE IMAGING AND MYELOGRAPHY IN 18 DOBERMAN PINSCHER DOGS WITH CERVICAL SPONDYLOMYELOPATHY

Eighteen Doberman pinscher dogs with clinical signs of cervical spondylomyelopathy (wobbler syndrome) underwent cervical myelography and magnetic resonance (MR) imaging. Cervical myelography was performed using iohexol, followed by lateral and ventrodorsal radiographs. Traction myelography was performed using a cervical harness exerting 9 kg of linear traction. MR imaging was performed in sagittal, transverse, and dorsal planes using a 1.5 T magnet with the spine in neutral and traction positions. Three reviewers independently evaluated the myelographic and MR images to determine the most extensive lesion and whether the lesion was static or dynamic. All reviewers agreed with the location of the most extensive lesion on MR images (100%), while the agreement using myelography was 83%. The myelogram and MR imaging findings agreed in the identification of the affected site in 13-16 dogs depending on the reviewer. MR imaging provided additional information on lesion location because it allowed direct examination of the spinal cord diameter and parenchyma. Spinal cord signal changes were seen in 10 dogs. Depending on the reviewer, two to four dogs had their lesions classified as dynamic on myelography but static on MR images. Myelography markedly underscored the severity of the spinal cord compression in two dogs, and failed to identify the cause of the signs in another. The results of this study indicated that, although myelography can identify the location of the lesion in most patients, MR imaging appears to be more accurate in predicting the site, severity, and nature of the spinal cord compression.     

Clinical signs,MRI features,and outcomes of two cats with thiamine deficiency secondary to diet change

Two cats were presented with vestibular signs and seizures. Both cats were diagnosed with thiamine deficiency. The transverse and dorsal T2-weighted magnetic resonance (MR) images revealed the presence of bilateral hyperintense lesions at specific nuclei of the midbrain, cerebellum, and brainstem. After thiamine supplementation, the clinical signs gradually improved. Repeated MR images taken 3 weeks after thiamine supplementation had started showed that the lesions were nearly resolved. This case report describes the clinical and MR findings associated with thiamine deficiency in two cats.