What is meant by DWI in MRI?
What is meant by DWI in MRI?
Abstract. Diffusion weighted imaging (DWI) is a method of signal contrast generation based on the differences in Brownian motion. DWI is a method to evaluate the molecular function and micro-architecture of the human body.
What is DWI sequence?
Diffusion-weighted magnetic resonance imaging (DWI or DW-MRI) is the use of specific MRI sequences as well as software that generates images from the resulting data that uses the diffusion of water molecules to generate contrast in MR images.
What is DWI and ADC in MRI?
Apparent diffusion coefficient (ADC) is a measure of the magnitude of diffusion (of water molecules) within tissue, and is commonly clinically calculated using MRI with diffusion-weighted imaging (DWI) 1.
What is Intraconal and Extraconal?
The intraconal compartment contains the globe, the optic nerve-sheath complex, orbital vessels. and nerves (Fig. 1). The extraconal compartment consists of the bony orbital walls, fat. and the lacrimal gland.
How common are orbital tumors?
Conclusions: Orbital tumors in the senior adult population are malignant in 63% of cases. Malignant lymphoma is the most common tumor in this age group, accounting for 24% of cases. Overall, 25% of patients have systemic problems related to the orbital process develop, so systemic evaluation is warranted.
What is the most common malignancy of the orbit?
Breast cancer is the most common malignancy to metastasize to the orbit, followed by prostate cancer, melanoma, and lung cancer. In women with bilateral enophthalmos, metastatic scirrhous breast cancer should be considered in the differential diagnosis.
What does a orbital tumor look like?
Most patients with orbital tumors notice a bulging of the eye or proptosis. But usually before the eye starts to bulge, changes in vision, double vision, or pain can be a presenting sign of an orbital tumor.
How are hyperintensities related to small vessel disease?
It is generally believed that these hyperintensities are related to vascular pathology, particularly small vessel disease. Periventricular hyperintensities may be related to blood–brain barrier (BBB) disruption or intraparenchymal venular disease (Black, Gao, & Bilbao, 2009).
Why do I have areas of hypointensity and hyperintensity?
The lesion may have areas of hypointensity that reflect areas of calcification ( Fig. 43.10). On T2-weighted MR images, the lesion has areas of iso- or hyperintensity due to its fatty content with areas of hyperintensity, as would be seen in an epidermoid.
How are white matter hyperintensities detected in the brain?
White matter hyperintensities are lesions in the brain that can be detected by T2-weighted MRI on which these lesions show up with increased brightness.
What are focal hyperintensities in the subcortical white matter?
Focal hyperintensities in the subcortical white matter demonstrated by T2-weighted or FLAIR images are a common incidental finding in patients undergoing brain MRI for indications other than stroke. They are indicative of chronic microvascular disease.