Optimization of Gradient-Echo Imaging Parameters for Intracaval Filters and Trapped Thromboemboli
| Autor: | George P. Teitelbaum, Alyssa T. Watanabe, Rachael A. Clark, Matthew D. Rifkin, Alan H. Matsumoto, Simon Vinitski, Klemens H. Barth, Hector V. Ortega |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Adult
Male Time Factors Vena Cava Inferior Hemoglobins Nuclear magnetic resonance Flip angle Thromboembolism medicine Humans Radiology Nuclear Medicine and imaging Methemoglobin Aged Aged 80 and over medicine.diagnostic_test business.industry Echo time Magnetic resonance imaging Middle Aged Hb - Hemoglobin Magnetic Resonance Imaging Magnetic susceptibility Gradient echo imaging Models Structural Repetition Time Female business Filtration circulatory and respiratory physiology A titanium |
| Zdroj: | Radiology. 174:1013-1019 |
| ISSN: | 1527-1315 0033-8419 |
| Popis: | Flow-phantom magnetic resonance (MR) gradient-echo (GRE) imaging at 1.5 T was performed on a titanium Greenfield filter containing trapped blood clots with a high concentration of either deoxyhemoglobin (DHb) or methemoglobin (MHb), simulating acute and older thromboemboli, respectively. Flip angle, repetition time (TR), and echo time (TE) were varied, and a contrast-to-noise ratio between trapped clots and flowing fluid (clot-flow contrast) was determined for each set of imaging parameters. Use of very low flip angles (less than or equal to 10 degrees) rendered MHb clots indistinguishable from flowing fluid. In general, DHb clots displayed greater clot-flow contrast than MHb clots regardless of flip angle. With increasing TE values, T2* effect was observed with MHb clots, and magnetic susceptibility artifacts increased. Overall, optimum clot-flow contrast for imaging of both DHb and MHb clots was achieved with a flip angle of 45 degrees-60 degrees, a TR of 50 msec, and the shortest TE possible. Using GRE parameters similar to the optimum parameters determined in vitro, the authors imaged four patients with nickel-titanium Simon filters and one dog with a titanium Greenfield filter. MR imaging was successful in demonstrating filter location, caval patency, and the presence and extent of intraluminal thrombus. |
| Databáze: | OpenAIRE |
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