Machine learning predicts histologic type and grade of canine gliomas based on MRI texture analysis.

Conventional MRI features of canine gliomas subtypes and grades significantly overlap. Texture analysis (TA) quantifies image texture based on spatial arrangement of pixel intensities. Machine learning (ML) models based on MRI-TA demonstrate high accuracy in predicting brain tumor types and grades in human medicine. The aim of this retrospective, diagnostic accuracy study was to investigate the accuracy of ML-based MRI-TA in predicting canine gliomas histologic types and grades. Dogs with histopathological diagnosis of intracranial glioma and available brain MRI were included. Tumors were manually segmented across their entire volume in enhancing part, non-enhancing part, and peri-tumoral vasogenic edema in T2-weighted (T2w), T1-weighted (T1w), FLAIR, and T1w postcontrast sequences. Texture features were extracted and fed into three ML classifiers. Classifiers' performance was assessed using a leave-one-out cross-validation approach. Multiclass and binary models were built to predict histologic types (oligodendroglioma vs. astrocytoma vs. oligoastrocytoma) and grades (high vs. low), respectively. Thirty-eight dogs with a total of 40 masses were included. Machine learning classifiers had an average accuracy of 77% for discriminating tumor types and of 75.6% for predicting high-grade gliomas. The support vector machine classifier had an accuracy of up to 94% for predicting tumor types and up to 87% for predicting high-grade gliomas. The most discriminative texture features of tumor types and grades appeared related to the peri-tumoral edema in T1w images and to the non-enhancing part of the tumor in T2w images, respectively. In conclusion, ML-based MRI-TA has the potential to discriminate intracranial canine gliomas types and grades.

Grading of oligodendroglioma in dogs based on magnetic resonance imaging.

BACKGROUND: Oligodendroglioma (OG) accounts for 22% of primary brain tumors in dogs. Oligodendroglioma in dogs is graded as low-grade (II) or high-grade (III), based on the presence of microvascular proliferation and necrosis. OBJECTIVE: To investigate if magnetic resonance imaging (MRI) features differ between OG II and III in dogs. ANIMALS: Thirty-two dogs with histological diagnosis of intracranial OG and MRI. METHODS: Retrospective descriptive study. Histology was reviewed to grade OG according to the revised classification. Brain MRI results were reviewed following criteria including contrast enhancement (CE) pattern, presence of cystic structures, gradient-recalled-echo (GRE) signal voids, and necrosis based on signal intensity, as well as diffusion-weighted imaging characteristics. The MRI features were compared between OG II and III using Fisher's exact tests and logistic regression models. RESULTS: Histology identified 8 dogs with OG II (25%) and 24 with OG III (75%). All OG III showed moderate-to-marked CE including 18/24 (75%) with a ring pattern. These features were not seen in OG II. Heterogeneity, cystic structures, GRE signal voids, and necrosis were associated with OG III. No difference in diffusion characteristics was detected between OG II and III. CONCLUSION AND CLINICAL IMPORTANCE: Moderate-to-marked CE and ring pattern were present in dogs with OG III but not in OG II. The presence of cystic structures, GRE signal voids, and necrosis was strongly associated with OG III. Although the importance of brain tumor grading in dogs with regard to prognosis and treatment options remains unknown, the results indicate that MRI reflects the histological features used for grading OG in dogs.

Feline gastrointestinal eosinophilic sclerosing fibroplasia presenting as a rectal mass.

Case summary: A 9-year-old neutered male cat was referred owing to dyschezia and weight loss. Abdominal CT revealed a heterogeneous mass in the rectum and thickening of one caudal mesenteric lymph node. The mass induced a focal rectal obstruction. Cytological evaluation of fine-needle aspirates showed signs of mixed inflammation for the rectal mass and a reactive lymph node. Because a definite diagnosis was not achieved, complete resection of the mass via a dorsal approach to the rectum was attempted. Histopathology confirmed complete removal and diagnosed feline gastrointestinal eosinophilic sclerosing fibroplasia (FGESF). The cat was treated with psyllium husks and lactulose after surgery. In the postoperative year, the owner reported normal behaviour, food intake and defecation of the patient. Dyschezia reoccurred 14 months after surgery. Imaging revealed recurrence of a rectal mass. Owing to clinical deterioration, the owner elected for euthanasia. Relevance and novel information: This is the first report of rectal FGESF with dyschezia and weight loss as the main clinical signs. The case demonstrates an acceptable outcome for more than 1 year without additional immunosuppressive therapy, and emphasises that FGESF must be considered as a differential diagnosis for rectal masses in cats.

Dilated cardiomyopathy in a cat with congenital hyposomatotropism.

Case summary: A 7-month-old domestic shorthair cat was presented for evaluation of stunted growth, recurrent hypoglycaemia during the first months of its life and altered mentation. Complete blood count and biochemistry were unremarkable, except for mildly elevated serum creatinine concentration (despite low muscle mass) and concurrent isosthenuria. Hyposomatotropism was diagnosed based on persistent low circulating insulin-like growth factor 1 concentrations and a lack of response of circulating growth hormone (GH) concentration after the administration of GH-releasing hormone. Other endocrinopathies such as hypothyroidism and hypoadrenocorticism were excluded. MRI of the brain revealed a fluid-filled empty sella tursica, consistent with a pituitary cyst and atrophy/hypoplasia of the pituitary. Echocardiography was unremarkable at the time of diagnosis of hyposomatotropism. Three months later, ovariohysterectomy revealed immature ovaries, raising the suspicion of luteinising and follicle-stimulating hormone deficiency. At 1 year of age, the cat developed congestive heart failure secondarily to dilated cardiomyopathy (DCM) with severely reduced left ventricular systolic function and died a few days later. Pathology showed atrophy of the adenohypophysis, epithelial delineation of the pituitary cysts, mild cardiomegaly, multifocal fibrosis of the left ventricle and a mild, multifocal, chronic epicarditis. Relevance and novel information: GH deficiency is a very rare endocrinopathy in cats. This is the first case to describe the development of DCM with concurrent hyposomatotropism, which has previously been reported in human medicine. Other notable abnormalities that could be related to GH deficiency are juvenile self-limiting hypoglycaemia, behavioural changes and possible nephropathy.

Clinical signs, MRI findings and long-term outcomes of foraminal and far lateral thoracolumbar intervertebral disc herniations in dogs.

BACKGROUND: As they have been seldomly described in the veterinary literature, the aims of this retrospective study were to describe the clinical presentation, MRI findings and long-term outcome after medical or surgical treatment of dogs presenting with foraminal and far lateral thoracolumbar intervertebral disc herniations. METHODS: Retrospective multicentre study of dogs diagnosed with foraminal and far lateral thoracolumbar intervertebral disc herniations between 2009 and 2020 in seven referral hospitals. RESULTS: Thirty-seven dogs were included. Dachshunds and mixed breeds were most affected. Median age at presentation and duration of clinical signs were 6 years and 14 days, respectively. Pain was the most frequent clinical finding (92%), particularly on spinal palpation and/or hip manipulation, followed by pelvic limb lameness (71%). Eighty-seven percent of herniations occurred at L5-L6 or L6-L7. A good to excellent outcome was seen in 95% of surgically and 90% of medically treated dogs. CONCLUSION: Although much less frequently recognised than herniation affecting the vertebral canal, foraminal and far lateral thoracolumbar intervertebral disc herniations should be considered in the differential diagnosis list of chondrodystrophic dogs presenting with pain and pelvic limb lameness. Most dogs had a good to excellent outcome following medical or surgical treatment.

Clinical and magnetic resonance imaging features of lymphoma involving the nervous system in cats.

BACKGROUND: Lymphoma is the most common spinal cord neoplasm and second most common intracranial tumor in cats, but description of specific magnetic resonance imaging (MRI) features is lacking. OBJECTIVE: Describe the clinical and MRI features of lymphoma affecting the central (CNS) or peripheral (PNS) nervous system or both in cats. ANIMALS: Thirty-one cats with confirmed cytological or histopathological diagnosis or both of lymphoma involving the CNS or PNS or both, and MRI findings of the lesions. METHODS: Multicenter retrospective descriptive study. Signalment and medical information were recorded. Magnetic resonance imaging findings were reviewed by 3 observers following a list of predefined criteria and consensus was sought. Frequency distributions of the different categorical data were reported. RESULTS: Median duration of clinical signs at time of presentation was 14 days (range, 1-90). Neurological examination was abnormal in 30/31 cats. On MRI, lesions affecting the CNS were diagnosed in 18/31 cats, lesions in both CNS and PNS in 12/31, and lesions in the PNS only in 1/31. Intracranial lesions were diagnosed in 22 cats (extra-axial, 7/22; intra-axial, 2/22; mixed, 13/22), and spinal lesions were diagnosed in 12 (6/12 involving the conus medullaris and lumbosacral plexuses). Infiltration of adjacent extra-neural tissue was present in 11/31 cases. Contrast enhancement was seen in all lesions, being marked in 25/30. Meningeal enhancement was present in all but 2 cases. Several distinct MRI patterns were observed. CONCLUSIONS AND CLINICAL IMPORTANCE: Nervous system lymphoma in cats has a wide range of MRI features, of which none is pathognomonic. However, together with clinical data and cerebrospinal fluid (CSF) analysis, MRI may provide a strong tentative antemortem diagnosis.

Total laryngectomy in a cat with a laryngeal peripheral nerve sheath tumor.

OBJECTIVE: To report the surgical technique and outcome of total laryngectomy in a single clinical case. STUDY DESIGN: Case report. ANIMAL: A 5-year-old female spayed domestic shorthair cat. METHODS: A cat presented for acute, severe respiratory distress caused by an invasive laryngeal mass. Incisional biopsy was indicative of sarcoma. Computed tomography of head, neck, and thorax was performed revealing no evidence of metastasis. A total laryngectomy and permanent tracheostomy were performed, and the cat could breathe without difficulties immediately postoperatively. Histopathology confirmed a laryngeal low-grade peripheral nerve sheath tumor (PNST). RESULTS: Surgical margins were free of tumor cells. Surgical revision of the tracheostomy stoma due to obstructive granulation tissue was necessary 24 days after the initial surgery. Nine days after revision surgery, the cat was discharged from the hospital. No evidence of local recurrence or metastasis was detected on repeat computed tomography of the head, neck, and thorax at 6 months, nor on chest radiographs at 12 months postoperatively. At the time of writing (13 months postoperatively), the cat is still alive with a good quality of life. CONCLUSION: Total laryngectomy with permanent tracheostomy allowed the complete removal of an obstructive laryngeal PNST and provided a good quality of life in a cat. CLINICAL SIGNIFICANCE: To the authors' knowledge, this case report represents the first detailed description of the surgical procedure and clinical outcome for a total laryngectomy in a cat.

Case report of unilateral retrobulbar hematoma associated with von Willebrand disease in a Doberman Pinscher dog.

A 5-year-old Doberman Pinscher dog was presented with sudden onset left-sided periocular bleeding following third eyelid gland replacement surgery. Left-sided exophthalmos and 360-degrees subconjunctival hemorrhage were present. The ophthalmic examination revealed blindness with absent direct and consensual pupillary light reflexes. A superficial exposure ulcerative keratitis due to exophthalmos was also present. Computed tomography (CT) revealed a large left-sided retrobulbar mass lesion surrounding the optic nerve, compatible with a retrobulbar hematoma. Due to absence of orbital fractures and no history of trauma, a coagulopathy was strongly suspected. The buccal mucosal bleeding time (BMBT) was prolonged (>4 minutes) consistent with a primary hemostatic defect in the absence of thrombocytopenia. Von Willebrand factor antigens levels were decreased (24%- Normal Range: 50%-150%). Surgical drainage of the retrobulbar hematoma was performed uneventfully thirty minutes after subcutaneous injection of desmopressine acetate, Minirin® (1 µg/kg, SC). Von Willebrand disease type I gene mutation was confirmed by PCR amplification of the DNA encoding von Willebrand factor. This case report demonstrates that hemostatic disorders, including von Willebrand Disease (vWD), are a risk factor for orbital bleeding following surgical trauma. Retrobulbar hematoma should be considered as a differential diagnosis in any dog with exophthalmos.

Aventriculi associated with holoprosencephaly in a dog.

CASE DESCRIPTION: A 10-month-old neutered male mixed breed dog was presented for assessment of poorly controlled seizures. CLINICAL FINDINGS: Magnetic resonance imaging of the brain disclosed complete absence of the lateral and third ventricles and mesencephalic aqueduct. Postmortem computed tomographic (CT) imaging and positive contrast cisterno-ventriculography confirmed the lack of a contiguous ventricular system. However, histopathology identified the presence of vestigial lateral and third ventricles with hypoplastic choroid plexus, atresia of the third ventricle, and fused thalami, consistent with a diagnosis of lobar holoprosencephaly (HPE). CLINICAL RELEVANCE: To our knowledge, this report is the first case of radiographically confirmed aventriculi associated with HPE, a rare congenital malformation previously reported in people, to be described in veterinary medicine.

Traumatic skull fractures in dogs and cats: A comparative analysis of neurological and computed tomographic features.

BACKGROUND: Traumatic skull fractures (TSF) are relatively frequent in dogs and cats, but little information is available regarding their clinical and imaging features. HYPOTHESIS/OBJECTIVES: To describe the neurological and computed tomographic (CT) features of a large cohort of dogs and cats with TSF. ANIMALS: Ninety-one dogs and 95 cats with TSF identified on CT. METHODS: Multicenter retrospective comparative study. Signalment, cause of trauma, fracture locations and characteristics, presence of neurological deficits, and 1-week survival were recorded. Fractures were classified according to the extent of fragmentation and displacement. RESULTS: The cranial vault was affected more frequently in dogs (P = .003), whereas the face and base of the cranium more often was affected in cats (P < .001). Cats presented with multiple fractures more frequently (P < .001). All animals with TSF in the cranial vault were more likely to develop neurological signs (P = .02), especially when depressed fractures were present (95% confidence interval [CI], 1.7-8.2; P = .001). Animals with TSF located only in the facial region were less likely to have neurological signs (odds ratio with Mantel-Haenszel's method [ORMH ], 0.2; 95% CI, 0.1-0.6; P = .004). Most affected animals (84.9%) survived the first week post-trauma. Death was more likely with fractures of the cranial vault (P = .003), especially when fragmented (P = .007) and displaced (P = .004). CONCLUSIONS AND CLINICAL IMPORTANCE: Traumatic skull fracture distribution and patterns are different between dogs and cats. Cranial vault fractures were associated with neurological deficits and worse survival. The presence of TSF alone should not be considered a negative prognostic factor because most affected animals survived the first week.

Minimally invasive spine surgery in dogs: Evaluation of the safety and feasibility of a thoracolumbar approach to the spinal cord.

OBJECTIVE: To describe the safety and feasibility of a minimally invasive spine surgery technique to access the thoracolumbar vertebral canal in dogs. STUDY DESIGN: Prospective study. ANIMALS: Six healthy research dogs. METHODS: Dogs were placed under anesthesia for MRI to evaluate vertebral column and spinal cord integrity. Minimally invasive surgery was performed at multiple sites. Access to the vertebral canal was achieved by means of foraminotomy, discectomy, and lateral minicorpectomy by using minimally invasive access and a surgical microscope. Sequential neurological examinations, pressure algometry pain quantification, and creatine kinase levels were evaluated before and after surgery for 7 days. Magnetic resonance imaging, computed tomography, and histopathology were performed on day 6 postoperatively after animals were humanely killed to evaluate the impact of surgery on spinal cord, muscles, and bone. RESULTS: The vertebral canal was successfully accessed, and the ventral aspect of the spinal cord was identified at all sites. No neurological deterioration was observed. Postoperative pain was not different compared with baseline except in one dog on the day after surgery. CONCLUSION: Minimally invasive spine surgery was a safe and feasible technique to access the thoracolumbar vertebral canal and the ventral aspect of the spinal cord in dogs. Findings supported postoperative pain benefits. CLINICAL SIGNIFICANCE: Minimally invasive spine surgery is a valid surgical technique to access the thoracolumbar vertebral canal at single or multiple sites in dogs.

A major facilitator superfamily domain 8 frameshift variant in a cat with suspected neuronal ceroid lipofuscinosis.

A 2-year-old male domestic shorthair cat was presented for a progressive history of abnormal posture, behavior, and mentation. Menace response was absent bilaterally, and generalized tremors were identified on neurological examination. A neuroanatomical diagnosis of diffuse brain dysfunction was made. A neurodegenerative disorder was suspected. Magnetic resonance imaging findings further supported the clinical suspicion. Whole-genome sequencing of the affected cat with filtering of variants against a database of unaffected cats was performed. Candidate variants were confirmed by Sanger sequencing followed by genotyping of a control population. Two homozygous private (unique to individual or families and therefore absent from the breed-matched controlled population) protein-changing variants in the major facilitator superfamily domain 8 (MFSD8) gene, a known candidate gene for neuronal ceroid lipofuscinosis type 7 (CLN7), were identified. The affected cat was homozygous for the alternative allele at both variants. This is the first report of a pathogenic alteration of the MFSD8 gene in a cat strongly suspected to have CLN7.

Clinical and magnetic resonance imaging findings of a cerebellar medulloblastoma in a heifer.

Reports of medulloblastoma in cattle are scarce; however, this neoplasm should be included as a differential diagnosis in cases of cerebellar or central vestibular signs in young cattle. The MRI appearance of the medulloblastoma reported here, previously unreported in cattle, consisted of a T1-weighted hypointense and T2-weighted heterogeneously hyperintense intra-axial mass.

Cryptococcosis with ocular and central nervous system involvement in a 3-year-old dog.

To date, cryptococcosis remains sporadic in Europe, and this is a case of canine cryptococcosis with ocular and CNS involvement in continental Europe with identification of the organism on cerebral spinal fluid (CSF) cytology and description of the clinical and MRI features, and outcome.

Use of computed tomography to define a sacral safe corridor for placement of 2.7 mm cortical screws in feline sacroiliac luxation.

Objectives This study aimed to define a safe corridor for 2.7 mm cortical sacroiliac screw insertion in the dorsal plane (craniocaudal direction) using radiography and CT, and in the transverse plane (dorsoventral direction) using CT in feline cadavers. A further aim was to compare the values obtained by CT with those previously reported by radiography in the transverse plane. Methods Thirteen pelvises were retrieved from feline cadavers and dissected to expose one of the articular surfaces of the sacrum. A 2.7 mm screw was placed in the sacrum to a depth of approximately 1 cm in each exposed articular surface. Dorsoventral radiography and CT scanning of each specimen were performed. Multiplanar reconstructions were performed to allow CT evaluation in both the dorsal and transverse planes. Calculations were made to find the maximum, minimum and optimum angles for screw placement in craniocaudal (radiography and CT) and dorsoventral (CT) directions when using a 2.7 mm cortical screw. Results Radiographic measurement showed a mean optimum craniocaudal angle of 106° (range 97-112°). The mean minimum angle was 95° (range 87-107°), whereas the mean maximum angle was 117° (108-124°). Measurement of the dorsal CT scan images showed a mean optimum craniocaudal angle of 101° (range 94-110°). The mean minimum angle was 90° (range 83-99°), whereas the mean maximum angle was 113° (104-125°). The transverse CT scan images showed a mean dorsoventral minimum angle of 103° (range 95-113°), mean maximum angle of 115° (104-125°) and mean optimum dorsoventral angle of 111° (102-119°). Conclusions and relevance An optimum craniocaudal angle of 101° is recommended for 2.7 mm cortical screw placement in the feline sacral body, with a safety margin between 99° and 104°. No single angle can be recommended in the dorsoventral direction and therefore preoperative measuring on individual cats using CT images is recommended to establish the ideal individual angle in the transverse plane.

Vertebral venous system abnormalities identified with magnetic resonance imaging in sighthounds.

In humans, abnormalities of the vertebral venous system are considered rare but significant causes of radiculopathy and myelopathy. Published information on abnormalities of the canine vertebral venous system is currently lacking. Aims of this retrospective descriptive study were to characterize magnetic resonance imaging (MRI) abnormalities of the vertebral venous system in a population of sighthounds, report prevalence of vertebral venous system abnormalities within that population and explore possible clinical significance. Our hospital database was searched over the period of 2002-2013 for sighthounds with MRI studies of the vertebral column. Medical records and MRI studies for included dogs were retrieved and findings were recorded by a single observer. A total of 92 sighthounds were sampled. Eleven cases (prevalence 12%) showed abnormal enlargement of the internal vertebral venous plexus (10/11 unilaterally, 1/11 bilaterally), external vertebral venous plexus (7/11 cases unilaterally), and/or intervertebral veins (8/11 unilaterally, 2/11 bilaterally, and 1/11 unilaterally and bilaterally at different sites). The majority of the abnormalities were right sided and the most common location for abnormalities was C6/7. Of the 11 cases, nine did not have a definitive diagnosis. Seven of those nine cases had an abnormality in a neuroanatomical localization that could wholly or partly explain the clinical signs. Findings indicated that, while the prevalence of vertebral venous system abnormalities was low in this sample of sighthounds, the majority of dogs with these abnormalities had clinical signs that matched the location of the abnormalities. Further prospective research is needed to investigate potential underlying aetiologies for vertebral venous system abnormalities in dogs and clarify their clinical significance.

Establishment of normal anatomical radial angles in cats.

OBJECTIVES: 1) To describe a radiographic method for determination of joint orientation lines and anatomical joint angles in orthogonal planes of feline radii; 2) to establish a range of normal radial joint orientation angles and anatomical axes in a feline population; and 3) to assess the repeatability and reliability of this methodology. METHODS: The radial anatomical axis, elbow and carpal joint reference lines, and the intersecting angles of each: anatomical medial proximal (aMPRA) and lateral distal radial angles (aLDRA), anatomical caudal proximal (aCdPRA) and distal radial angles (aCdDRA), and sagittal procurvatum (SP) were determined on the orthogonal radiographs of 14 feline limbs. Intra- and inter-observer agreement was determined based on repeated independent readings by two observers using Bland-Altman plots. RESULTS: The mean ± standard deviation (SD) and 95% confidence interval (CI) for the feline radii were: aMPRA 70.97 ± 3.38° (70.07 - 71.88°), aLDRA 91.72 ± 3.26° (90.84 - 92.59°), aCdPRA 100.5 ± 3.14° (99.62 - 101.3º), aCdDRA 79.95 ± 3.77° (78.94 - 80.96°) and SP 11.07 ± 1.87° (10.57 - 11.58°). The highest mean bias found for both observers was -1.6 to -1.8° for the angle aCdDRA. Sagittal procurvatum had the lowest mean bias for intra- and inter-observer. CLINICAL SIGNIFICANCE: The results obtained showed that the methodology used in our study was repeatable and reliable. The values established for the normal radial anatomical angles are relevant for future use as a reference for surgical treatment of angular deformities, malunions, non-unions, comminuted fractures, and future orthopaedic research.

Intra-parenchymal brainstem haemorrhage secondary to iatrogenic needle injury after a parenteral injection in a cat.

CASE SUMMARY: A 6-month-old female domestic shorthair cat was presented with acute onset non-ambulatory right hemiparesis and horizontal nystagmus following an injection attempt in the neck, during which the cat did not cooperate. Magnetic resonance imaging (MRI) revealed a well-defined intra-axial lesion on the right side of the myelencephalon. The lesion was T2-weighted hypointense and T1-weighted hypointense to isointense to grey matter, non-contrast enhancing, with perilesional oedema and signal void on T2*-weighted images. A linear hyperintense lesion in the muscles of the right dorsolateral aspect of the neck on short tau inversion recovery images was also observed. These MRI findings were consistent with iatrogenic brainstem haemorrhage and a muscle needle tract. The cat made a good recovery with just mild residual neurological deficits 6 weeks after the injury. RELEVANCE AND NOVEL INFORMATION: To our knowledge, this is the first report of an iatrogenic brainstem needle injury in a cat and the first report of a central nervous system iatrogenic trauma after a parenteral injection. Care should be taken with neck parenteral injections, especially in the cranial cervical area.