It is shown that diffusion tensor MR imaging (DTI) can discretely delineate the microstructure of white matter and gray matter in embryonic and early postnatal mouse brains based on the existence and orientation of ordered structures. This order was found not only in white matter but also in the cortical plate and the periventricular zone, which are precursors of the cerebral cortex. This DTI-based information could be used to accomplish the automated spatial definition of the cortical plate and various axonal tracts. The DTI studies also revealed a characteristic evolution of diffusion anisotropy in the cortex of the developing brain. This ability to detect changes in the organization of the brain during development will greatly enhance morphological studies of transgenic and knockout models of cortical dysfunction. With the advent of murine models of disease and development generated by gene engineering, a new noninvasive technique is needed to characterize 3D morphological changes appearing over time in the brain. At present, the microscopic anatomical analyses of mammalian developmental studies are almost exclusively based on the histological examination. While this technique is most effective for examining microscopic changes in developing brains, it is not particularly suitable to characterize large-scale morphology, such as the anatomy of the entire brain. Although it is possible to reconstruct a macroscopic 3D-volume dataset using serial histological sections and stereology, this is an extremely labor-intensive process (1,2). To examine global anatomy in developing mouse brains, MRI technology is especially promising (3,4) because it can provide a 3D dataset without sectioning and is free of artifacts related to brain deformation or missing tissue due to imperfect sectioning. The data are intrinsically numerical and quantification for shape and volume analyses is more straightforward. Similar to various staining techniques for histological preparations, MRI also provides a family of contrast types based on the physical properties of water. For example, mouse embryonic imaging has been performed using proton density T 1 -and T 2 -weighted images (3-6). While these imaging methods can provide clear contrast for various tissue compartments in the entire body, it is not always optimal for the differentiation of compartments within the brain because of small differences in T 1 and T 2 relaxation parameters in young brains (7,8). Moreover, even in adult brains conventional MRI methods are not suitable to differentiate various white matter tracts within the brain white matter.In this report, we apply an MRI technology called diffusion tensor imaging (DTI) (9,10) to study mouse brain development from a period starting at embryonic day 15.5 in utero to adult. This technique uses water diffusion to probe tissue microstructure. For example, in regions where axon tracts form an ordered environment, water diffusion has directionality (anisotropy). Application of this technique to the adult brain has revealed that whi...
In patients with X-ALD, MR spectroscopic imaging can depict abnormalities in white matter that have a normal appearance on both conventional MR and DT images; this finding suggests that it may be the most sensitive technique for detecting early abnormalities of demyelination or axonal loss in patients with X-ALD.
To elucidate the characteristics of pulmonary metastatic nodules on high-resolution computed tomographic (HRCT) scans, a correlative computed tomographic (CT)-pathologic study was performed with five human lungs after autopsy. The relationship of metastatic nodules to pulmonary vessels was studied with HRCT scans, radiographs of the specimen, and stereomicroscopic study in 264 nodules 0.6-9.0 mm in diameter. On radiographs and stereomicroscopic images, 190 small nodules (less than 3 mm in diameter) were in contact with the pulmonary lobule on the central bronchovascular bundles (n = 33 [17.4%]), located between the central bronchovascular bundle and the perilobular structure (n = 127 [66.8%]), or attached to perilobular structures (n = 30 [15.8%]). On HRCT scans, 21 small nodules (11.1%) were located on the central bronchovascular bundle; 130 small nodules (68.4%), between the central bronchovascular bundle and the perilobular structure; and 39 small nodules (20.5%), on the perilobular structure. On radiographs and stereomicroscopic images, 43 of 74 large nodules (greater than 3 mm in diameter) (58%) compressed both bronchovascular bundles and perilobular structures. The central bronchovascular bundle was invaded in only 13 large nodules (18%).
We developed software with which we can generate brain images of a wide range of pulse sequences and that allows us to specify the location, size, shape, and intrinsic characteristics of simulated lesions. We found that the use of FLAIR sequences increases detection accuracy for cortical-subcortical and periventricular lesions over that associated with proton density- and T2-weighted sequences.
FSE T2-weighted imaging is a reliable method with which to assess the sella with sufficient resolution after transsphenoidal surgery. The combination of unenhanced SE T1-weighted and FSE T2-weighted images may reduce the use of contrast material after pituitary surgery.
Using an MR simulator, we can define thresholds below which changes in original lesion size cannot be reliably detected. These results may guide the design of clinical trials that rely on trained reviewers to assess change in lesion burden.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.