[Basic principles and technique of diffusion-weighted imaging and diffusion tensor imaging].

Area of Science:

• Biophysics
• Medical Imaging
• Neuroscience

Context:

• Water molecules in tissue exhibit random motion (diffusion), which differs in pathological conditions like ischemia, inflammation, and neoplasia.
• Diffusion-weighted magnetic resonance (MR) imaging (DWI) quantifies this motion, offering diagnostic information beyond traditional imaging.
• Standard clinical DWI uses directionally averaged images (trace maps), while Diffusion Tensor Imaging (DTI) explores diffusional anisotropy for microstructure insights.

Purpose:

• To summarize the principles and clinical applications of diffusion-weighted MRI (DWI) and Diffusion Tensor Imaging (DTI).
• To highlight DWI's ability to detect and characterize pathological tissue changes.
• To explain how DTI visualizes tissue microstructure and aids in surgical and radiation therapy planning.

Summary:

• Diffusion-weighted MRI sequences, often based on echo planar imaging (EPI), utilize strong magnetic field gradients to sensitize MR signals to water molecule diffusion.
• Deviations in diffusion strength from normal values indicate pathological processes, with DWI providing unique image contrast.
• DTI, an advanced DWI method, analyzes diffusional anisotropy to reconstruct and visualize tissue fiber structure, offering valuable microstructural information.

Impact:

• Diffusion-weighted MRI is an established technique for assessing pathological processes, particularly in stroke diagnostics.
• Its application is expanding to detect and characterize diverse lesions throughout the body.
• DTI's ability to visualize neural tracts is crucial for surgical and radiation therapy planning in the brain and spinal cord.