The most common application of conventional DWI (without DTI) is in acute brain ischemia. DWI directly visualizes the ischemic necrosis in cerebral infarction in the form of a cytotoxic edema, appearing as a high DWI signal within minutes of arterial occlusion. With perfusion MRI detecting both the infarcted core and the salvageable penumbra, the latter can be quantified by DWI and perfusion MRI. File:Cerebral infarction after 4 hours on DWI MRI.DWI showing necrosis (shown as brighter) in a cerebral infarction File:MRI DWI sequence showing restricted<unk>  in the mesial dorsal thalami.DWI showing restricted<unk>  in the medial dorsal thalami consistent with Wernicke encephalopathy File:Melas dwi ax.DWI showing cortical ribbon-like high signal consistent with<unk>  restriction in a patient with known MELAS syndrome Another application area of DWI is in oncology. Tumors are in many instances highly cellular, giving restricted<unk>  of water, and therefore appear with a relatively high signal intensity in DWI. DWI is commonly used to detect and stage tumors, and also to monitor tumor response to treatment over time. DWI can also be collected to visualize the whole body using a technique called<unk> -weighted whole-body imaging with background body signal suppression' (DWIBS). Some more specialized<unk>  techniques such as<unk>  kurtosis imaging (DKI) have also been shown to predict the response of cancer patients to chemotherapy treatment. The principal application is in the imaging of white matter where the location, orientation, and anisotropy of the tracts can be measured. The architecture of the axons in parallel bundles, and their myelin sheaths, facilitate the<unk>  of the water molecules preferentially along their main direction. Such preferentially oriented<unk>  is called anisotropic<unk> . Tractographic reconstruction of neural connections via DTI See https://doi.org/10.3389/fsurg.2020.00019 for more information The imaging of this property is an extension of<unk> . If a series of<unk>  gradients (i.e. magnetic field variations in the MRI magnet) are applied that can determine at least 3 directional vectors (use of 6 different gradients is the minimum and additional gradients improve the accuracy for "off-diagonal" information), it is possible to calculate, for each voxel, a tensor (i.e. a symmetric positive definite 3×3 matrix) that describes the 3-dimensional shape of<unk> . The fiber direction is indicated by the tensor's main eigenvector. This vector can be color-coded, yielding a cartography of the tracts' position and direction (red for left-right, blue for superior-inferior, and green for anterior-posterior). The brightness is weighted by the fractional anisotropy which is a scalar measure of the degree of anisotropy in a given voxel. Mean diffusivity (MD) or trace is a scalar measure of the total<unk>  within a voxel. These measures are commonly used clinically to localize white matter lesions that do not show up on other forms of clinical MRI. Applications in the brain: * Tract-specific localization of white matter lesions such as trauma and in defining the severity of diffuse traumatic brain injury. The localization of tumors in relation to the white matter tracts (infiltration, deflection), has been one of the most important initial applications. In surgical planning for some types of brain tumors, surgery is aided by knowing the proximity and relative position of the corticospinal tract and a tumor. *<unk>  tensor imaging data can be used to perform tractography within white matter. Fiber tracking algorithms can be used to track a fiber along its whole length (e.g. the corticospinal tract, through which the motor information transit from the motor cortex to the spinal cord and the peripheral nerves). Tractography is a useful tool for measuring deficits in white matter, such as in aging. Its estimation of fiber orientation and strength is increasingly accurate, and it has widespread potential implications in the fields of cognitive neuroscience and neurobiology. * The use of DTI for the assessment of white matter in development, pathology and degeneration has been the focus of over 2,500 research publications since 2005. It promises to be very helpful in distinguishing Alzheimer's disease from other types of dementia. Applications in brain research include the investigation of neural networks in vivo, as well as in connectomics. Applications for peripheral nerves: * Brachial plexus: DTI can differentiate normal nerves (as shown in the tractogram of the spinal cord and brachial plexus and 3D 4k reconstruction here) from traumatically injured nerve roots. * Cubital Tunnel Syndrome: metrics derived from DTI (FA and RD) can differentiate asymptomatic adults from those with compression of the ulnar nerve at the elbow * Carpal Tunnel Syndrome: Metrics derived from DTI (lower FA and MD) differentiate healthy adults from those with carpal tunnel syndrome
Diffusion MRI
Blood-oxygen-level-dependent imaging
Neuroproteomics
Perfusion MRI
Susceptibility weighted imaging
Amplified magnetic resonance imaging
Functional imaging
Magnetic resonance spectroscopic imaging