Direct Thrombus Imaging

In contrast to most imaging techniques, which delineate thrombus as flow void or contrast filling defect, magnetic resonance direct thrombus imaging visualizes thrombus against a suppressed background (Fig. 3). During the process of thrombus formation, a predictable reduction in the T1 value of the clot occurs reflecting the presence of methe-moglobin. High signal intensity occurs initially at the periphery of the clot which, over time, extends toward the center. In addition to the signal generated by the thrombus itself, further contrast of a clot against blood can be created by nulling the unclot-ted blood signal using an inversion recovery pulse. Background signal on the T1-weighted image can be further suppressed through selective radio-fre-

Fig. 3a, b. Oblique reformatted display of thrombus extending from the calf vein into the politeal vein displayed by (a) direct thrombus imaging (no contrast administration) and (b) indirect contrast-enhanced MR venography. Whereas the thrombus (arrows) shows bright signal intensity with the direct thrombus imaging approach, on the contrast enhanced image the thrombus is visualized as filling defect

Fig. 3a, b. Oblique reformatted display of thrombus extending from the calf vein into the politeal vein displayed by (a) direct thrombus imaging (no contrast administration) and (b) indirect contrast-enhanced MR venography. Whereas the thrombus (arrows) shows bright signal intensity with the direct thrombus imaging approach, on the contrast enhanced image the thrombus is visualized as filling defect quency excitation of water molecules to reduce the fat signal. The technique has been shown to be useful for the detection of acute DVT [ 14].

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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