Diffusion-weighted MR imaging DWI is a technique used to assess the random Brownian motion of water molecules within a certain voxel of tissue. In other words, DWI is used to determine the ease of molecular diffusivity of water within a tissue. Many pathologies cause restricted extracellular diffusion of water protons including infarction, cytotoxic edema, high cellularity within tissue, viscous fluid, demyelination, and metabolic disturbances. Restricted diffusion is seen as high-signal intensity on DWI with corresponding reduced apparent diffusion coefficient ADC values. ADC is a measurement of the diffusion of water molecules in a given tissue.
The Who and Why of MRI
Imaging of Acute Ischemic Stroke | Radiology Key
Ischemic stroke results from a sudden cessation of adequate amounts of blood reaching parts of the brain. Ischemic strokes can be divided according to territory affected or mechanism. Stroke is the second most common cause of morbidity worldwide after myocardial infarction and is the leading cause of acquired disability 2. Risk factors for ischemic stroke largely mirror the risk factors for atherosclerosis and include age, gender, family history, smoking, hypertension, hypercholesterolemia, and diabetes mellitus.
Early Signs of Brain Ischemia on CT and MR; Can AI Lend a Helping Hand?
T he use of radiologic studies in the ophthalmic setting is becoming increasingly more common, especially for neuro-ophthalmic disorders. Many eye care providers now routinely order various types of neuroimaging studies that provide valuable and detailed information on neural visual pathways not easily obtained through clinical examination alone. The most commonly ordered diagnostic test is magnetic resonance imaging MRI because it allows imaging of the orbital apex and optic nerve despite the dense bone surrounding these areas.
Increased DWI signal in ischemic brain tissue is observed within a few minutes after arterial occlusion and progresses through a stereotypic sequence of apparent diffusion coefficient ADC reduction, followed by subsequent increase, pseudo-normalization and, finally, permanent elevation. For a general discussion of the pathogenesis and radiographic features please refer to ischemic stroke. Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. Updating… Please wait. Unable to process the form.