Renal MRI includes unenhanced axial SGE T1, fat suppresed T2 and DWI B 500. Coronal T1 and T2 weighted iamges are obtaomed. The coronal and axilal T1 images are used to assess for fat in an angiomyolipoma. The T2 SSFSE images will best characterize renal cysts.
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bowel
Signal in MR images is high or low (bright or dark), depending on the pulse sequence used, and the type of tissue in the image region of interest. The following is a general guide to how tissue appears on T1- or T2- weighted images.
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Diffusion weighted imaging (DWI) is designed to detect the random movements of water protons. Water molecules diffuse relatively freely in the extracellular space; their movement is significantly restricted in the intracellular space. Spontaneous movements, referred to as diffusion, rapidly become restricted in ischemic brain tissue. During ischemia, the sodium - potassium pump shuts down and sodium accumulates intracellularly. Water then shifts from the extracellular to the intracellular space due to the osmotic gradient. As water movement becomes restricted intracellularly, this results in an extremely bright signal on DWI. Thus, DWI is an extremely sensitive method for detecting acute stroke.