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A non-invasive method for studying the modifications induced in lipid depots by hormonal stimulation could extend knowledge of adipose tissues. We studied the effect of adrenergic stimulation on interscapular brown adipose tissue (IBAT) of rats using contrast-enhanced MRI. Controls and rats pre-treated with adrenaline 40 s before the acquisition of pre-contrast images were used. In the control group, IBAT showed an enhancement of 56 ± 29%, whereas adrenaline pre-treatment resulted in a significantly higher value (83 ± 49%, P < 0.05). In the control group, the skeletal muscle of the anterior limb showed an enhancement of 24 ± 12%, while adrenaline pre-treatment led to a higher value (26 ± 10%), although the difference was not significant. In the control group, the skeletal muscle adjacent to the IBAT showed an enhancement of 30 ± 13%, while adrenaline pre-treatment resulted in a non-significantly higher value (33 ± 10%). In both groups, enhancement values in the muscle adjacent to the IBAT were significantly higher than the values in the muscle of the anterior limb ( P < 0.05). This study demonstrates the feasibility of detecting the effect of hormonal stimulation on small fat depots. The demonstration of greater blood flow in the muscles surrounding the IBAT than in the muscles of the anterior limb suggests that the muscles of the back operate in synergy with the IBAT. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Purpose To detect and quantify pulmonary lesions due to pneumococcal pneumonia in a murine model by 1H MRI. Materials and Methods Pneumonia was induced in mice ( N = 5) by intranasal administration of about 1 × 106 colony-forming units (CFU) of Streptococcus pneumonie. A group of noninfected animals ( N = 5) was used as a control group. MRI was performed, 48 hours after infection induction, at 4.7 T. ECG-gated gradient-echo (GRE) sequences with TE = 5 msec were used. After MRI examination, the animals were sacrificed for histological examination. Results Lungs appeared at MRI as regions with signal intensity (SI) at the level of the noise. Lesions appeared as hyperintense regions over the background and were localized mainly in the apical part of the lungs, in the medial and peribronchial regions. The anatomical localization of the lesions was confirmed by histology. The total lesion volume quantified by MRI data correlated with the total lesion volume quantified by histology. Conclusion This work shows that standard 1H MRI allows detection and quantification of lesions due to pneumococcal pneumonia in mice. J. Magn. Reson. Imaging 2005;22:170-174. © 2005 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Seven human fetuses of crown/rump length corresponding to gestational ages ranging from the 12th to the 16th week were studied using a paradigm based on three-dimensional reconstruction of the brain obtained by magnetic resonance imaging (MRI). The aim of the study was to evaluate brain morphology in situ and to describe developmental dynamics during an important period of fetal morphogenesis. Three-dimensional MRI showed the increasing degree of maturation of the brains; fronto-occipital distance, bitemporal distance and occipital angle were examined in all the fetuses. The data were interpreted by correlation with the internal structure as visualized using high-spatial-resolution MRI, acquired using a 4.7-T field intensity magnet with a gradient power of 20 G cm−1. The spatial resolution was sufficient for a detailed detection of five layers, and the contrast was optimized using sequences with different degrees of T1 and T2 weighting. Using the latter, it was possible to visualize the subplate and marginal zones. The cortical thickness was mapped on to the hemispheric surface, describing the thickness gradient from the insular cortex to the periphery of the hemispheres. The study demonstrates the utility of MRI for studying brain development. The method provides a quantitative profiling of the brain, which allows the calculation of important morphological parameters, and it provides informative regarding transient features of the developing brain. [ABSTRACT FROM AUTHOR]

Purpose: To compare T1- or T2-weighted magnetic resonance imaging (MRI) and ultrasonography (US) as tools for in vivo mapping of different tissue components in spontaneous tumors of transgenic mice. Materials and Methods: Human-like mammary adenocarcinomas from FVB/neuT transgenic mice were analyzed by T2-weighted and T1-weighted MRI at 4.7 Tesla and US and then, after excision, were paraffin-embedded for histologic analysis. The histologic samples were prepared taking care to obtain sections that spatially matched the MRI and US images as precisely as possible. Results: US can obtain basic information such as the size of developing tumors in experimental animals and can identify necrotic areas. T2-weighted MRI, especially if compared to T1-weighted MRI and/or US, allows advanced analysis of morphologic aspects, with high resolution in the differentiation of details of necrotic areas such as coagulation, liquefaction, biphasic splitting of cysts, and fibrotic and lipidic infiltration. Conclusion: Of the three methods, T2-weighted MRI provides the most information about the anatomy of tumors. However, when distinctions between the different types of necrosis are not needed, US analysis is to be preferred for its practicality. [ABSTRACT FROM AUTHOR]