S. Ródenas

Magnetic resonance imaging findings in 40 dogs with histologically confirmed intracranial tumours.

Magnetic resonance (MR) images of 40 dogs with histologically confirmed primary and secondary intracranial tumours were reviewed. Forty-one tumours were diagnosed by means of MR imaging (MRI). MRI findings allowed diagnosis of a neoplastic lesion in 37/41 cases. Based on MRI features, differentiation between neoplastic and non-neoplastic lesions was possible in 24/27 (89%) primary brain tumours and in 13/14 (92%) secondary brain tumours. Diagnosis of tumour type based on MRI features was correct in 19/27 (70%) primary tumours and in 13/14 secondary tumours. The results of this study show that MRI is a good diagnostic imaging modality to detect neoplastic lesions and to diagnose tumour type in dogs. However, as some neoplasms show equivocal MRI features the technique has limitations in the detection of some intracranial tumours and in predicting tumour type.

Acute postretinal blindness: ophthalmologic, neurologic, and magnetic resonance imaging findings in dogs and cats (seven cases)

OBJECTIVE To describe the ophthalmologic, neurologic, and magnetic resonance imaging (MRI) findings of seven animals with acute postretinal blindness as sole neurologic deficit. METHODS Medical records were reviewed to identify dogs and cats with postretinal blindness of acute presentation, that had a cranial MRI performed as part of the diagnostic workup. Only animals lacking other neurologic signs at presentation were included. Complete physical, ophthalmic, and neurologic examinations, routine laboratory evaluations, thoracic radiographs, abdominal ultrasound, electroretinography, and brain MRI were performed in all animals. Cerebrospinal fluid analysis and postmortem histopathologic results were recorded when available. RESULTS Four dogs and three cats met the inclusion criteria. Lesions affecting the visual pathways were observed on magnetic resonance (MR) images in six cases. Location, extension, and MRI features were described. Neuroanatomic localization included: olfactory region with involvement of the optic chiasm (n = 4), pituitary fossa with involvement of the optic chiasm and optic tracts (n = 1), and optic nerves (n = 1). Of all lesions detected, five were consistent with intracranial tumors (two meningiomas, one pituitary tumor, two nasal tumors with intracranial extension), and one with bilateral optic neuritis that was confirmed by cerebrospinal fluid analysis. Histologic diagnosis was obtained in four cases and included one meningioma, one pituitary carcinoma, one nasal osteosarcoma, and one nasal carcinoma. CONCLUSIONS Central nervous system (CNS) disease should be considered in dogs and cats with acute blindness, even when other neurologic deficits are absent. This study emphasizes the relevance of MRI as a diagnostic tool for detection and characterization of CNS lesions affecting the visual pathways.

Myelographic and low-field magnetic resonance imaging findings in dogs with presumptive acute hydrated non-compressive nucleus pulposus extrusion

MRI is considered gold standard for the diagnosis of presumptive acute hydrated non-compressive nucleus pulposus extrusions (AHNCNPE). This retrospective study describes the myelographic findings in dogs with AHNCNPE diagnosed by low-field MRI and their association with neurological grade, need of surgical decompression and outcome. Forty-two myelographies (21 dogs with presumptive AHNCNPE, 21 dogs with Hansen type I disc disease herniation) were blindly evaluated. Site of herniation, compression pattern, ratio of length of the lesion to length of the second lumbar vertebra (LL:L2) and degree of spinal cord compression (SCC) were measured on the myelographies of dogs with presumptive AHNCNPE and were compared with the corresponding MRI features. Percentage of extruded volume of nucleus pulposus (VNP) was calculated on MR images. Myelographic interobserver agreement for presumptive diagnosis of AHNCNPE was almost perfect (κ=0.8). Accuracy of myelography to detect site of herniation was 80.9 per cent and to identify extradural compression was 57.1 per cent. Mean SCC was 5.8±2.6 per cent for myelography and 6.6±3 per cent for MRI. Mean LL:L2 ratio was 1.7±0.9 for myelography and 1.2±0.8 for MRI. Mean percentage of extruded VNP was 40±14 per cent, and it was positively associated with neurological grade.

Clinical Features, Imaging Characteristics, and Long-term Outcome of Dogs with Cranial Meningocele or Meningoencephalocele

Background The term meningoencephalocele (MEC) describes a herniation of cerebral tissue and meninges through a defect in the cranium, whereas a meningocele (MC) is a herniation of the meninges alone. Hypothesis/Objectives To describe the clinical features, magnetic resonance imaging (MRI) characteristics, and outcomes of dogs with cranial MC and MEC. Animals Twenty‐two client‐owned dogs diagnosed with cranial MC or MEC. Methods Multicentric retrospective descriptive study. Clinical records of 13 institutions were reviewed. Signalment, clinical history, neurologic findings and MRI characteristics as well as treatment and outcome were recorded and evaluated. Results Most affected dogs were presented at a young age (median, 6.5 months; range, 1 month – 8 years). The most common presenting complaints were seizures and behavioral abnormalities. Intranasal MEC was more common than parietal MC. Magnetic resonance imaging identified meningeal enhancement of the protruded tissue in 77% of the cases. Porencephaly was seen in all cases with parietal MC. Cerebrospinal fluid (CSF) analysis identified mild abnormalities in 4 of 11 cases. Surgery was not performed in any affected dog. Seventeen patients were treated medically, and seizures were adequately controlled with anti‐epileptic drugs in 10 dogs. Dogs with intranasal MEC and mild neurologic signs had a fair prognosis with medical treatment. Conclusion and clinical importance Although uncommon, MC and MEC should be considered as a differential diagnosis in young dogs presenting with seizures or alterations in behavior. Medical treatment is a valid option with a fair prognosis when the neurologic signs are mild.

Imaging diagnosis-magnetic resonance imaging findings of an intracranial epidural tuberculoma in a dog.

Magnetic resonance (MR) imaging is highly sensitive for detecting tuberculomas in human patients but the specificity of the MR imaging features is low. Misdiagnosis with intracranial neoplasia is common, especially with dural-based lesions or lesions located in the epidural space. We describe the MR imaging characteristics of an intracranial epidural tuberculoma caused by Mycobacterium tuberculosis infection in a dog. The intracranial mass and skull flat bone lysis and erosion are similar to those described in human caseating tuberculomas and can mimic intracranial neoplastic disease.