Magnetic resonance imaging for the differentiation of neoplastic, inflammatory, and cerebrovascular brain disease in dogs.

BACKGROUND: The reliability and validity of magnetic resonance imaging (MRI) for detecting neoplastic, inflammatory, and cerebrovascular brain lesions in dogs are unknown. OBJECTIVES: To estimate sensitivity, specificity, and inter-rater agreement of MRI for classifying histologically confirmed neoplastic, inflammatory, and cerebrovascular brain disease in dogs. ANIMALS: One hundred and twenty-one client-owned dogs diagnosed with brain disease (n = 77) or idiopathic epilepsy (n = 44). METHODS: Retrospective, multi-institutional case series; 3 investigators analyzed MR images for the presence of a brain lesion with and without knowledge of case clinical data. Investigators recorded most likely etiologic category (neoplastic, inflammatory, cerebrovascular) and most likely specific disease for all brain lesions. Sensitivity, specificity, and inter-rater agreement were calculated to estimate diagnostic performance. RESULTS: MRI was 94.4% sensitive (95% confidence interval [CI] = 88.7, 97.4) and 95.5% specific (95% CI = 89.9, 98.1) for detecting a brain lesion with similarly high performance for classifying neoplastic and inflammatory disease, but was only 38.9% sensitive for classifying cerebrovascular disease (95% CI = 16.1, 67.0). In general, high specificity but not sensitivity was retained for MR diagnosis of specific brain diseases. Inter-rater agreement was very good for overall detection of structural brain lesions (κ = 0.895, 95% CI = 0.792, 0.998, P < .001) and neoplastic lesions, but was only fair for cerebrovascular lesions (κ = 0.299, 95% CI = 0, 0.761, P = .21). CONCLUSIONS AND CLINICAL IMPORTANCE: MRI is sensitive and specific for identifying brain lesions and classifying disease as inflammatory or neoplastic in dogs. Cerebrovascular disease in general and specific inflammatory, neoplastic, and cerebrovascular brain diseases were frequently misclassified.

Reproducibility of individual rates of ethanol metabolism in fasting subjects.

To estimate variability in ethanol metabolism, eight normal men received oral doses of 95% ethanol (1 ml/kg) after an overnight fast on each of 4 successive weeks. For each subject, slopes of linear decay curves of blood ethanol were highly reproducible--coefficients of variation ranged from 3% for the least variable subject to 12% for the most variable subject (mean, 8%). Compared to this low intraindividual variation, interindividual variation was slightly higher--the mean coefficient of interindividual variation was 14%, with a range from 10% to 17%. A one-way ANOVA with repeat measures showed that on any one of four separate occasions of ethanol administration, the eight subjects differed from one another (p less than 0.01), but that each subject remained similar from one test to another. The consumption of food before ethanol administration increased variability. Fever associated with upper respiratory infection also increased variability, but exercise did not.

Effects of exercise and of food restriction on adipose tissue cellularity.

The body weight and fat content of young, growing rats were kept low by regularly performed endurance exercise by the rats or by restriction of their food intake over a period of 14 wk. The cellular character of epididymal fat pads was studied to determine if the reduction in fat was due to a decrease in the number of adipose cells, their size, or both. Compared with the sedentary freely eating control animals, both the exercisers and the sedentary paired-weight animals, which had their food intake restricted in order to maintain their body weights approximately the same as those of the exercisers, had significantly lighter epididymal fat pads (P < 0.001). This fat depot in the exercisers contained fewer (4.46 +/- 0.48 x 10(6) vs. 6.89 +/- 0.55 x 10(6) cells/pad; P < 0.001) and smaller (0.286 +/- 0.041 vs. 0.462 +/- 0.040 micro g of lipid/cell; P < 0.001) cells than that in the sedentary freely eating animals. Food restriction also resulted in a significant reduction in adipose tissue cellularity (P < 0.05). Epididymal fat pads from the calorie-restricted rats had an average of 5.72 +/- 0.33 x 10(6) cells and they contained 0.319 +/- 0.024 micro g of lipid/cell. These results demonstrate that exercise in addition to food restriction in early life is effective in reducing the rate of accumulation of cells in epididymal fat pads of rats.