development of a deep convolutional neural network to predict grading of canine meningiomas from magnetic resonance images

Abstract An established deep neural network (DNN) based on transfer learning and a newly designed DNN were tested to predict the grade of meningiomas from magnetic resonance (MR) images in dogs and to determine the accuracy of classification of using pre- and post-contrast T1-weighted (T1W), and T2-weighted (T2W) MR images. The images were randomly assigned to a training set, a validation set and a test set, comprising 60%, 10% and 30% of images, respectively. The combination of DNN and MR sequence displaying the highest discriminating accuracy was used to develop an image classifier to predict the grading of new cases. The algorithm based on transfer learning using the established DNN did not provide satisfactory results, whereas the newly designed DNN had high classification accuracy. On the basis of classification accuracy, an image classifier built on the newly designed DNN using post-contrast T1W images was developed. This image classifier correctly predicted the grading of 8 out of 10 images not included in the data set

The binary progenitors of short and long GRBs and their gravitational-wave emission

We have sub-classified short and long-duration gamma-ray bursts (GRBs) into seven families according to the binary nature of their progenitors. Short GRBs are produced in mergers of neutron-star binaries (NS-NS) or neutron star-black hole binaries (NS-BH). Long GRBs are produced via the induced gravitational collapse (IGC) scenario occurring in a tight binary system composed of a carbon-oxygen core (COcore) and a NS companion. The COcore explodes as type Ic supernova (SN) leading to a hypercritical accretion process onto the NS: if the accretion is sufficiently high the NS reaches the critical mass and collapses forming a BH, otherwise a massive NS is formed. Therefore long GRBs can lead either to NS-BH or to NS-NS binaries depending on the entity of the accretion. We discuss for the above compact-object binaries: 1) the role of the NS structure and the nuclear equation of state; 2) the occurrence rates obtained from X and gamma-rays observations; 3) the predicted annual number of detections by the Advanced LIGO interferometer of their gravitational-wave emission

Thiamine deficiency in a cat: resolution of MRI abnormalities following thiamine supplementation

Thiamine (vitamin B(1)) is an essential component of a number of metabolic pathways and thiamine deficiency results in a progressive encephalopathy in both humans and animals. Confirming thiamine deficiency is problematic and relies on demonstrating reduced red blood cells transketolase activity, or indirect methods including urinary organic acid analysis and dietary analysis. The characteristic and selective vulnerability of different brain regions in carnivores has been demonstrated by magnetic resonance (MR) imaging in the dog and cat as an aid to diagnosis. A 2-year-old, female, domestic shorthair cat was presented with an acute onset of seizures and ataxia. MR imaging was consistent with thiamine deficiency and supplementation resulted in a progressive clinical improvement. Repeated MR imaging 4 days after starting thiamine supplementation revealed near complete resolution of the MR abnormalities. Repeated MR imaging following appropriate therapy may be useful to further confirm thiamine deficiency

Convergence-Retraction Pulses in a Dog With Ischaemic Encephalomyelopathy

Convergence-retraction pulses (or “nystagmus) are a highly localizing saccadic abnormality of the dorsal midbrain syndrome in humans and dogs. Ischaemic encephalomyelopathy attributed to presumptive fibrocartilaginous embolism (FCE) has been reported in human, dog and lamb, whilst FCE encephalopathy was reported recently in a cat. The aim of this study is to report the clinical and imaging findings of a rare case of ischaemic encephalomyelopathy due to presumptive FCE with manifestation of convergence-retraction pulses and an excellent outcome. A 6.5-year-old client-owned male neutered Trailhound was admitted for hyperacute non-progressive non-painful left-sided hemiparesis developed during exercise. Physical examination revealed obesity and bilateral conjunctival hyperaemia. Neurological examination revealed non-painful left-sided poorly-ambulatory hemiparesis; decreased left-sided postural reactions and left thoracic limb spontaneous knuckling; thoracic limbs hyporeflexia; and no evidence of spinal pain. Neuroanatomical localisation was consistent with C6-T2 myelopathy. Haematology revealed stress-leukogram, whilst serum biochemistry revealed mild stress-hyperglycaemia, hypotriglyceridemia and mildly decreased alkaline phosphatase. The patient underwent a low-field magnetic resonance imaging (MRI) of the C1-T2 spinal segments which revealed a focal intramedullary lesion at C6-C7 spinal segments compatible with FCE. On the second day of hospitalisation, the patient suddenly developed “nystagmus”. Neurological examination revealed spontaneous-and-positional convergence-retraction pulses accompanied by synchronous blinking, mydriasis and upward gaze palsy (Collier’s sign) bilaterally. Ambulation and postural reactions were unchanged. The neuroanatomical localisation now was consistent with an additional dorsal midbrain syndrome. MRI of the brain revealed a focal, poorly-marginated, left-lateralized, hyperintense lesion on T2-weighted and fluid fluid-attenuated inversion recovery (FLAIR) sequences, at the level of the rostral midbrain. In transverse images, this lesion was visible adjacent to the midline (left-sided) and lateral to the rostral part of the mesencephalic aqueduct. This area was hyperintense on diffuse-weighting imaging (DWI) sequence, but did not suppress on apparent diffusion coefficient (ADC) mapping or uptake contrast. These findings were compatible with an ischaemic infarct in the rostral aspect of the dorsal midbrain. Cisternal cerebellomedullary cerebrospinal fluid (CSF) analysis revealed albuminocytological dissociation, with occasional monocytes, rare neutrophils and small lymphocytes. The finding of neutrophils in the absence of pleocytosis could be associated with cerebrovascular accident. Oscillometric arterial blood pressure revealed an average of 147/93 (mean106) mmHg. Ophthalmological examination, ophthalmoscopy, endocrine profile (TT4, TSH, basal cortisol, ACTH stimulation test), coagulation profile (BMBT, PT, APTT, D-dimers), ANA serology, extended infectious agents panel (blood serology and CSF PCR), urinalysis, urine culture, abdominal ultrasound and thoracic computed tomography were all unremarkable. Consequently, ischaemic encephalomyelopathy due to presumptive multifocal FCE was diagnosed. The dog was kept hospitalised for one week while received physiotherapy. At the time of discharge, the dog was ambulatory hemiparetic with normal haematology. On a three-week follow-up the dog was normal. The “nystagmus” was reported to have resolved within two weeks from onset. This is a rare report of a dog with multiple simultaneous central nervous system ischaemic infarctions which manifested convergence-retraction pulses and had an excellent outcome. This neuro-ophthalmological sign should be considered as a guide to localise precisely. FCE should be considered in the differential diagnoses for a dog with ischaemic encephalomyelopathy

Convergence-Retraction Pulses in a Dog With Ischaemic Encephalomyelopathy

Convergence-retraction pulses (or “nystagmus) are a highly localizing saccadic abnormality of the dorsal midbrain syndrome in humans and dogs. Ischaemic encephalomyelopathy attributed to presumptive fibrocartilaginous embolism (FCE) has been reported in human, dog and lamb, whilst FCE encephalopathy was reported recently in a cat. The aim of this study is to report the clinical and imaging findings of a rare case of ischaemic encephalomyelopathy due to presumptive FCE with manifestation of convergence-retraction pulses and an excellent outcome. A 6.5-year-old client-owned male neutered Trailhound was admitted for hyperacute non-progressive non-painful left-sided hemiparesis developed during exercise. Physical examination revealed obesity and bilateral conjunctival hyperaemia. Neurological examination revealed non-painful left-sided poorly-ambulatory hemiparesis; decreased left-sided postural reactions and left thoracic limb spontaneous knuckling; thoracic limbs hyporeflexia; and no evidence of spinal pain. Neuroanatomical localisation was consistent with C6-T2 myelopathy. Haematology revealed stress-leukogram, whilst serum biochemistry revealed mild stress-hyperglycaemia, hypotriglyceridemia and mildly decreased alkaline phosphatase. The patient underwent a low-field magnetic resonance imaging (MRI) of the C1-T2 spinal segments which revealed a focal intramedullary lesion at C6-C7 spinal segments compatible with FCE. On the second day of hospitalisation, the patient suddenly developed “nystagmus”. Neurological examination revealed spontaneous-and-positional convergence-retraction pulses accompanied by synchronous blinking, mydriasis and upward gaze palsy (Collier’s sign) bilaterally. Ambulation and postural reactions were unchanged. The neuroanatomical localisation now was consistent with an additional dorsal midbrain syndrome. MRI of the brain revealed a focal, poorly-marginated, left-lateralized, hyperintense lesion on T2-weighted and fluid fluid-attenuated inversion recovery (FLAIR) sequences, at the level of the rostral midbrain. In transverse images, this lesion was visible adjacent to the midline (left-sided) and lateral to the rostral part of the mesencephalic aqueduct. This area was hyperintense on diffuse-weighting imaging (DWI) sequence, but did not suppress on apparent diffusion coefficient (ADC) mapping or uptake contrast. These findings were compatible with an ischaemic infarct in the rostral aspect of the dorsal midbrain. Cisternal cerebellomedullary cerebrospinal fluid (CSF) analysis revealed albuminocytological dissociation, with occasional monocytes, rare neutrophils and small lymphocytes. The finding of neutrophils in the absence of pleocytosis could be associated with cerebrovascular accident. Oscillometric arterial blood pressure revealed an average of 147/93 (mean106) mmHg. Ophthalmological examination, ophthalmoscopy, endocrine profile (TT4, TSH, basal cortisol, ACTH stimulation test), coagulation profile (BMBT, PT, APTT, D-dimers), ANA serology, extended infectious agents panel (blood serology and CSF PCR), urinalysis, urine culture, abdominal ultrasound and thoracic computed tomography were all unremarkable. Consequently, ischaemic encephalomyelopathy due to presumptive multifocal FCE was diagnosed. The dog was kept hospitalised for one week while received physiotherapy. At the time of discharge, the dog was ambulatory hemiparetic with normal haematology. On a three-week follow-up the dog was normal. The “nystagmus” was reported to have resolved within two weeks from onset. This is a rare report of a dog with multiple simultaneous central nervous system ischaemic infarctions which manifested convergence-retraction pulses and had an excellent outcome. This neuro-ophthalmological sign should be considered as a guide to localise precisely. FCE should be considered in the differential diagnoses for a dog with ischaemic encephalomyelopathy

The Cutaneous Trunci Reflex as a Localizing and Grading Tool in Dogs with Thoracolumbar Spinal Cord Injuries

No abstract available

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

Neurological abnormalities in 97 dogs with detectable pituitary masses

Background: Pituitary tumours are common neoplasms of the sellar region in small animals. However, detailed information regarding the spectrum and severity of possible neurological signs are lacking. Objective: To retrospectively describe the neurological abnormalities in a population of dogs with a detectable pituitary mass (DPM) and relate them with the size of the mass and magnetic resonance imaging (MRI) signs of brain compression (BC). Client-owned dogs were included in the study if they had MRI showing a DPM and a detailed neurological examination. The neurological signs were evaluated in relation to the pituitary height/brain ratio (P:B ratio) and the presence/absence of brain compression. Results: Ninety-seven dogs were enrolled. Besides abnormal mentation and behavior (77%), gait (61%) and cranial nerve abnormalities (44%), other unreported neurological signs observed included postural abnormalities (21%), pain and/or hyperesthesia (25%) and abnormal postural and proprioceptive reactions (49%). The majority of dogs with DPM had signs of BC. The presence of a high pituitary height/brain area and BC represented a risk factor for developing mental status abnormalities. Conclusion: Neurological signs recorded in DPM-affected dogs include not only the typical forebrain signs but also gait disturbances and hyperesthesia. Neurological signs are positively associated with increased P:B ratio and MRI signs of brain compression

Clinical features of muscle cramp in 14 dogs

Background: Muscle cramps (MCs) are prolonged, involuntary, painful muscle contractions characterized by an acute onset and short duration, caused by peripheral nerve hyperactivity. Objectives: To provide a detailed description of the clinical features and diagnostic findings in dogs affected by MCs. Animals: Fourteen dogs. Methods: Multicenter retrospective case series. Cases were recruited by a call to veterinary neurologists working in referral practices. Medical records and videotapes were searched for dogs showing MCs. The follow-up was obtained by telephone communication with the owner and the referring veterinarian. Results: Three patterns of presentation were identified depending on the number of affected limbs and presence/absence of migration of MCs to other limbs. In 9/14 (64%) of dogs, MCs were triggered by prompting the dogs to move. 8/14 (58%) dogs were overtly painful with 6/14 (42%) showing mild discomfort. The cause of MCs was hypocalcemia in 11/14 (79%) dogs: 9 dogs were affected by primary hypoparathyrodism, 1 dog by intestinal lymphoma and 1 dog by protein losing enteropathy. In 3/14 cases (21%) the cause was not identified, and all 3 dogs were German Shepherds. Conclusions and Clinical Importance: Muscle cramps can manifest in 1 of 3 clinical patterns. Muscle cramps are elicited when dogs are encouraged to move and do not always appear as painful events, showing in some cases only discomfort. The main cause of MCs in this study was hypocalcemia consequent to primary hypoparathyroidism. In dogs having MCs of unknown etiology, idiopathic disease or paroxysmal dyskinesia could not be ruled out

On the rate and on the gravitational wave emission of short and long GRBs

International audienceOn the ground of the large number of gamma-ray bursts (GRBs) detected with cosmological redshift, we classified GRBs in seven subclasses, all with binary progenitors which emit gravitational waves (GWs). Each binary is composed of combinations of carbon–oxygen cores (COcore), neutron stars (NSs), black holes (BHs), and white dwarfs (WDs). The long bursts, traditionally assumed to originate from a BH with an ultrarelativistic jetted emission, not emitting GWs, have been subclassified as (I) X-ray flashes (XRFs), (II) binary-driven hypernovae (BdHNe), and (III) BH–supernovae (BH–SNe). They are framed within the induced gravitational collapse paradigm with a progenitor COcore–NS/BH binary. The SN explosion of the COcore triggers an accretion process onto the NS/BH. If the accretion does not lead the NS to its critical mass, an XRF occurs, while when the BH is present or formed by accretion, a BdHN occurs. When the binaries are not disrupted, XRFs lead to NS–NS and BdHNe lead to NS–BH. The short bursts, originating in NS–NS, are subclassified as (IV) short gamma-ray flashes (S-GRFs) and (V) short GRBs (S-GRBs), the latter when a BH is formed. There are (VI) ultrashort GRBs (U-GRBs) and (VII) gamma-ray flashes (GRFs) formed in NS–BH and NS–WD, respectively. We use the occurrence rate and GW emission of these subclasses to assess their detectability by Advanced LIGO-Virgo, eLISA, and resonant bars. We discuss the consequences of our results in view of the announcement of the LIGO/Virgo Collaboration of the source GW 170817 as being originated by an NS–NS