Contrast-enhanced fluid-attenuated inversion recovery vs. contrast-enhanced spin echo T1-weighted brain imaging

In humans, contrast-enhanced fluid-attenuated inversion recovery (FLAIR) imaging plays an important role in detecting brain disease. The aim of this study was to define the clinical utility of contrast-enhanced FLAIR imaging by comparing the results with those with contrast-enhanced spin echo T1-weighted images (SE T1WI) in animals with different brain disorders. Forty-one dogs and five cats with a clinical suspicion of brain disease and 30 normal animals (25 dogs and five cats) were evaluated using a 0.2 T permanent magnet. Before contrast medium injection, spin echo T1-weighted, SE T1WI, and FLAIR sequences were acquired in three planes. SE T1WI and FLAIR images were also acquired after gadolinium injection. Sensitivity in detecting the number, location, margin, and enhancement pattern and rate were evaluated. No lesions were found in a normal animal. In affected animals, 48 lesions in 34 patients were detected in contrast-enhanced SE T1WI whereas 81 lesions in 44 patients were detected in contrast-enhanced FLAIR images. There was no difference in the characteristics of the margins or enhancement pattern of the detected lesions. The objective enhancement rate, the mean value between lesion-to-white matter ratio and lesion-to-gray matter ratio, although representing an overlap of T1 and T2 effects and not pure contrast medium shortening of T1 relaxation, was better in contrast-enhanced FLAIR images. These results suggest a superiority of contrast-enhanced FLAIR images as compared with contrast-enhanced SE T1WI in detecting enhancing brain lesions.     

Eosinophilic cerebrospinal fluid pleocytosis associated with neural Angiostrongylus vasorum infection in a dog

A 1‐year‐old, female intact Pug dog was presented to the Small Animal Teaching Hospital of the University of Liverpool with a 4‐week history of progressive multifocal intracranial signs. Magnetic resonance imaging (MRI) detected multiple hemorrhagic lesions in the brain. The Baermann and zinc sulfate flotation tests with centrifugation, performed on fecal samples, were positive for lungworm larvae and an antigenic test confirmed Angiostrongylus vasorum infection. Anthelmintic treatment was started with a consequent marked clinical improvement. Seventy days later, the dog was clinically normal, and no larvae were detected on the Baermann test. Repeat MRI of the brain revealed marked improvement of the hemorrhagic lesions. Cerebrospinal fluid analysis (CSF) showed marked eosinophilic pleocytosis, and anthelmintic treatment was restarted. A follow‐up CSF analysis 4 months after the first presentation revealed resolution of the eosinophilic pleocytosis. This is the first case report of marked eosinophilic pleocytosis associated with neural A vasorum infection in a dog. The CSF eosinophilic pleocytosis persisted for several weeks after treatment, even in the absence of concurrent clinical signs and with a negative A vasorum Baermann test.     

Successful surgical debridement of a cerebral Streptococcus equi equi abscess by parietal bone flap craniotomy in a 2-month-old Warmblood foal

Brain abscesses and intracranial masses have been regularly described in horses. Treatment often is difficult and unrewarding and mortality rate high. This case report describes the successful treatment of a cerebral abscess in a 2-month-old female Warmblood foal with severe neurological signs of acute onset. Computed tomography (CT) revealed a 3 × 4 × 4 cm cerebral mass in the left brain hemisphere with severe cerebral oedema. Craniotomy, using a parietal bone flap technique, allowed the abscess to be sampled, drained and lavaged. Immediately, post-surgery the foal showed significant clinical improvement. Sample culture confirmed Streptococcus equi equi infection. The foal was medically treated for 6 weeks, leading to complete clinical and radiographical recovery. Intracranial surgery in equine medicine is limited. Using a parietal bone flap instead of partial craniectomy to gain access to the cerebrum is a less invasive procedure leading to a better aesthetic result and should be considered for the treatment of cerebral masses in the horse.     

IMAGING DIAGNOSIS —ANTEMORTEM DETECTION OF OLIGODENDROGLIOMA “CEREBROSPINAL FLUID DROP METASTASES” IN A DOG BY SERIAL MAGNETIC RESONANCE IMAGING

An English Bulldog underwent radiation therapy of an intracranial, left lateral ventricle mass. Following resolution of the primary mass, an intraventricular fourth ventricle lesion developed. Subsequently, multiple lesions developed from the cervical central canal and leptomeninges. Serial magnetic resonance imaging documented the propagation of lesions along the cerebrospinal fluid (CSF) pathways, known as “CSF drop metastasis.” Histopathology confirmed multifocal intraventricular and leptomeningeal oligodendroglioma. Oligodendroglioma should be included in the differential diagnosis for an intraventricular tumor exhibiting apparent CSF drop metastasis.     

Relationships among neuroscore,magnetic resonance imaging features,and intracranial pressure in sheep affected by slow‐growing brain lesions

Diagnosing high intracranial pressure by clinical and diagnostic imaging is particularly challenging for chronic or slow‐growing lesions. The aim of this prospective case‐control study is to determine whether the neuroscore and brain magnetic resonance imaging (MRI) are related to the direct measurement of intracranial pressure in sheep affected by intracranial slow‐growing lesions due to chronic cerebral coenurosis (Coenurus cerebralis). Seventeen affected and 10 control sheep were included. All animals underwent a neurological examination, MRI of the brain, and direct measurement of intracranial pressure. The severity of clinical signs and MRI findings were scored. Data were statistically analyzed. The invasive intracranial pressure value was higher in affected animals. A severely altered neuroscore is related to an increased intracranial pressure beyond the normal threshold (P < 0.05). The volume of the calvarium was larger in affected animals than in control animals (P = 0.0001) and was positively influenced by the presence and volume of the parasitic cyst (r = 0.7881, P < 0.01). Several degrees of deviation and deformation of both the ventricular system and brain parenchyma were detected by MRI. Subjective MRI findings were not associated with intracranial hypertension. In conclusion, this study shows that in sheep affected by slow‐growing lesions, severe alterations in the neuroscore and the results of objective MRI are related to an increased intracranial pressure beyond the normal threshold.     

Effect of methotrexate exposure at late gestation on development of telencephalon in rat fetal brain

Pregnant rats were treated with 30 mg/kg of methotrexate (MTX) on gestation day (GD) 16, and fetal brains were examined time-dependently. On GD 20, the appearance of the telencephalon in the MTX group was different from that in the control group, and the major axis of the telencephalon of the MTX group was shortened, compared to that of the control group. In the sagittal section of the telencephalon in the MTX group on GD 20, histopathological findings of deformation and narrowing of the cerebral ventricle, the disturbance of the arrangement of the marginal cell layer of subventricular zone (SVZ) and thickening of telencephalic wall, cortical plate and ventricular zone (VZ)/SVZ were possibly attributable to neuronal migration disorders by MTX. Through all the experimental period, few pyknotic cells or TUNEL-positive cells were observed in the VZ/SVZ of the telencephalic wall and striatum in the control group. On the other hand, in the VZ/SVZ of the telencephalic wall and striatum in the MTX group, pyknotic cells or TUNEL-positive cells were observed on GD 17, and they increased significantly on GD18 and then decreased to the control levels from GD 19 onward. The phospho-Histone H3-positive rate decreased remarkedly in the VZ/SVZ of the telencephalic wall and striatum of the MTX group on GDs 17 and 18, compared to the control group, but they recovered on and after GD 19. These results suggested that there was a high possibility that development of the telencephalon in this period required strong folic acid.