T2*-weighted gradient-echo MRI images at high field (≥ 7 Tesla) have shown rich image contrast within and between brain regions. The source for these contrast variations has been primarily attributed to tissue magnetic susceptibility differences. In this study, the contribution of myelin to both T2* and frequency contrasts is investigated using a mouse model of demyelination based on a cuprizone diet. The demyelinated brains showed significantly increased T2* in white matter and a substantial reduction in gray-white matter frequency contrast, suggesting that myelin is a primary source for these contrasts. Comparison of in-vivo and in-vitro data showed that, although tissue T2* values were reduced by formalin fixation, gray-white matter frequency contrast was relatively unaffected and fixation had a negligible effect on cuprizone-induced changes in T2* and frequency contrasts.

No abstract

ABSTRACT. Administration of immunosuppressive doses of glucocorticosteroids is the traditional primary treatment in necrotizing meningoencephalitis (NME) in dogs. However, response is variable and clinical signs often recur quickly with tapering dosage. Prognosis is poor and long-term therapy causes many complications. In the present study, we compared the long-term effects of combination (cyclosporine plus prednisolone) therapy with sole prednisolone therapy in management in dogs with NME. All NME cases in this study were examined with magnetic resonance imaging and cerebrospinal fluid analysis, and confirmed by histopathologic examination. The mean survival time of combination therapy group was 305.7 ± 94.7 days. The mean survival time of sole prednisolone therapy group was 58.3 ± 30.5 days. This case report demonstrates that combination treatment of cyclosporine with prednisolone is more effective in survival time than administration of only prednisolone in NME cases.

The prevalence of feline herpesvirus-1 (FHV-1), feline calicivirus (FCV), and Chlamydophila (C.) felis was studied in cats of an animal shelter in Korea. Total 78 cats without ocular and upper respiratory tract disease were examined. Specimens were obtained from ocular conjunctiva and oropharynx. Using multiplex polymerase chain reaction (PCR) and reverse transcription PCR, three pathogens were simultaneously detected. In examined 78 cats, 49 (63%) cats were positive for FHV-1. However, all specimens were negative for C. felis and FCV. In conclusion, many cats recovered from FHV-1 infection remain subclinical carriers in shelter environment.

ABSTRACT. A 7-year-old castrated male mixed-breed dog was presented with a complaint of acute pain. The dog had suffered from isolated seizures for two years. Magnetic resonance imaging (MRI) of the brain revealed a smooth brain surface due to lack of gyri and sulci formation of the cerebrum and thick cortical grey matter. Additionally, ventriculomegaly and an arachnoid cyst were noted. Multiple spinal cord compressions induced by intervertebral disc protrusion were observed on a cervical MRI. Based on these findings, the dog was diagnosed as having lissencephaly concurrent with intervertebral cervical disease. After therapy for seizure and cervical pain, the clinical signs were completely resolved. To the author's knowledge, this is the case report to diagnose lissencephaly in a mixedbreed dog.

The aim of the present study was to assess the clinical and histopathological findings in a canine model of ischemic stroke. Cerebral ischemic stroke was induced by middle cerebral artery occlusion in four healthy beagle dogs using silicone plugs. They showed neurological signs of forebrain dysfunction such as reduced responsiveness, head turning, circling, postural reaction deficits, perceptual deficits, and hemianopsia. These signs gradually regressed within 4 weeks without therapy. On magnetic resonance imaging, T2 hyperintensity and T1 hypointensity were found in the cerebral cortex and basal ganglia. These lesions were well-defined and sharply demarcated from adjacent brain parenchyma with a homogenous appearance. No abnormalities of the cerebrospinal fluid were observed. At necropsy, atrophic and necrotic lesions were observed in the cerebral cortex. The cerebral cortex, basal ganglia, and thalamus were partially unstained with triphenyl-tetrazolium chloride. Histopathologically, typical features of infarction were identified in cortical and thalamic lesions. This study demonstrates that our canine model resembles the conditions of real stroke patients.

ABSTRACT. A 14-year-old male miniature schnauzer was referred to us because it was circling to the right. A mass in the diencephalon was noted on brain magnetic resonance images. The dura was thickened with marked linear enhancement after contrast administration. Based on diagnostic image analysis, this lesion strongly suggested meningioma. The patient's symptoms were well controlled by a combination therapy of prednisolone and lomustine (CCNU), and survived for thirteen months after diagnosis. This case was diagnosed as a meningioma based on histopathological findings. This report describes the clinical findings, imaging characteristics, and pathologic features of a diencephalic and mesencephalic meningioma and long-term survival after lomustine and prednisolone therapy. KEY WORDS: lomustine (CCNU), magnetic resonance imaging (MRI), meningioma.J. Vet. Med. Sci. 68(4): 383-386, 2006 Primary brain tumors include neoplasms that arise from brain parenchymal tissue, cells comprising the outer and inner lining of the brain, and vascular elements. Intracranial neoplasia is well described in the dog, and the incidence of brain tumors in this species may approach 3.0%. It has been reported that primary central nervous system tumors arising from mesodermal origin (meningioma) are the most common intracranial tumors in dogs, followed by neuroectoderm a l ( g l i a l ) t u m o r s ( e . g . , a s t r o c y t o m a a n d oligodendroglioma) [2,9,12].Diagnosis of specific tumor types from magnetic resonance imaging (MRI) characteristics is sometimes difficult in both people and animals, and a definitive diagnosis may depend upon incisional or excisional biopsies. Brain tumors exert their pathologic effects both by directly encroaching on and/or invading brain tissue and by such secondary effects as peritumoral edema, inflammation, obstructive hydrocephalus, and hemorrhaging. Treatment of dogs and cats with primary brain tumors can be divided conceptually into supportive and definitive therapy [2].A 14-year-old male miniature schnauzer with body weight of 5.8 kg was presented to the Veterinary Medical Teaching Hospital of Konkuk University due to a 4-week history of circling to the right and anorexia. Intermittent circling was observed first, and clinical signs worsened progressively. Neurological examination revealed continuous clock-wise circling. Cranial nerve deficits included both bilaterally decreased menace response (MR) and pupillary light reflex (PLR). Based on the neurological examination, clinical signs were likely due to a structural brain lesion. The results of complete blood count (CBC) profiles were within the reference range. Serum chemistry profiles showed increased alkaline phosphatase (581 U/L; reference range: 0 to 142 U/L) and alanine aminotransferase (82 U/L; reference range: 13 to 53 U/L).Thus, we performed a brain MR scan (E-scan; ESAOTE, Italy) using 0.2T unit. T1-and T2-weighted images and postcontrast T1-weighted images were obtained. MR scanning confirmed a mass in diencephalon and mesencephalon ...

A Yorkshire terrier and a Chihuahua were referred for acute onset, generalized tonic-clonic seizures and were suspected to have meningoencephalitis based on magnetic resonance (MR) imaging findings. Brain lesions appeared hyperintense with T2-weighted imaging and hypointense with T1-weighted imaging, and were characteristic of necrotizing meningoencephalitis. Both dogs were diagnosed with necrotizing meningoencephalitis based on pathologic findings. Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) was performed on both animals before euthanasia with the permission of the owner. In FDG-PET images, these lesions seen in MR images were characterized by multifocal or diffuse hypometabolism. Our FDG-PET results provided evidence of glucose hypometabolism in areas of necrosis and cavitation associated with necrotizing meningoencephalitis. FDG-PET has the potential to provide valuable diagnostic information in dogs with suspected necrotizing encephalitis.