The goal of all imaging procedures is generation of an image contrast with a good spatial resolution. Technical evolution of diffusion weighted imaging Diffusion tensor imaging (DTI) exploits this property to produce micro-architectural detail of white matter tracts and provides information about white matter integrity. Water diffusion is anisotropic in brain white matter, because axon membranes limit molecular movement perpendicular to the fibers. It adds a new dimension to the magnetic resonance imaging (MRI) examinations by adding functional information to the largely anatomical information gathered by the conventional sequences. Diffusion weighted imaging provides qualitative and quantitative information about the diffusion properties. For example in high grade malignancies and acutely infarcted tissues, intracellular proportion is increased, so the diffusion becomes relatively more restricted. The relative proportion of the water distribution between these compartments is affected by the pathologic processes. Different tissues of the human body have a characteristic cellular architecture and proportions of intra and extracellular compartments and hence have characteristic diffusion properties. Water molecules in extracellular environments experience relatively free diffusion while intracellular molecules show relatively “restricted diffusion”. But in a complex environment of human body, water is divided between cells and extracellular compartments. In a perfectly homogenous medium diffusion is random and isotropic i.e., equal probability in all directions. Diffusion is the random Brownian motion of the molecules driven by thermal energy. Approximately 60%-70% of the human body is composed of water.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |