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Interventional MR Angiography with a Floating Table¹

¹ From the Departments of Diagnostic and Interventional Radiology (H.H.Q., H.K., S.B., J.F.D., M.E.L.), Transplantation Surgery (G.K.), and Pathophysiology (S.A.), University Hospital Essen, Hufelandstr 55, D-45122 Essen, Germany. Received August 5, 2002; revision requested October 8; revision received January 29, 2003; accepted March 11. Supported by DFG grant no. LA 1325/1–1. Address correspondence to H.H.Q. (e-mail: hhquick@uni-essen.de).

View larger version (136K): [in a new window]   Figure 1. Floating table system mounted on top of the MR imaging table, which contains the built-in spinal-array (SA) RF surface coil. Imaging table cushions superior and inferior to the spinal-array surface coil are replaced by two roller boards (RB). The small roller board is connected to the coil glider (CG), which rests against the opening of the magnet bore. The coil glider hosts the body-array surface RF coil and centers the coil within the isocenter of the magnet. For imaging, a floating table is placed on top of the roller boards.

View larger version (115K): [in a new window]   Figure 2. Pig on top of the floating table, head first and supine with the legs fixed with gauze and tape. The floating table allows the fully anesthetized and ventilated pig to be moved manually between the spinal-array surface coil and the phased-array body flex coil that is mounted on the coil glider. A-C, Image series demonstrates how the pig is moved to position both surface coils at a new region of interest. For demonstration purposes, photographs were taken outside the bore of the imager.

View larger version (78K): [in a new window]   Figure 3. Advancement of an actively visualized guide wire and catheter from, A, the iliac artery through, B, the abdominal aorta into, C, the aortic arch of a pig. The MR images were acquired in the coronal plane. The actively visualized guide wire is displayed in red, while the catheter is displayed in green and yellow. The colored instrument outlines are overlaid onto the anatomic images that were acquired with the body and spinal-array coils (A-C). D-F, The corresponding images in the bottom row show schematically how the catheter is advanced into the pig while the pig, lying on the floating table, is moved out of the imager. Arrowheads indicate the catheter tip. This procedure ensures that the moving region of interest always stays within the FOV that is covered by the body and spinal-array coils of the imager (black rectangles anterior and posterior to the pig). Imaging parameters were true FISP with 2.2/1.1, flip angle of 50°, FOV of 30 x 30 cm, matrix of 256 x 135, section width of 10 mm, bandwidth of 1,085 Hz/pixel, and frame rate of 3.4 images per second without any echo sharing.

View larger version (72K): [in a new window]   Figure 4. Biplanar real-time MR images show the advancement of an actively visualized guide wire (red) and catheter (green and yellow) from the iliac artery through the abdominal aorta into the aortic arch of a pig. A-E, Images acquired in the coronal plane. F-J, Corresponding images acquired in the sagittal plane. Ten of 360 acquired frames are shown. As soon as the advancing instruments reached the top edge of the FOV (B and G), the pig was manually pulled out of the imager while the instruments were advanced further (C-E and H-J). This always kept the catheter tip within the visible FOV. Arrowheads mark the anatomic position of the diaphragm. Imaging parameters were identical to those in Figure 3, and frame rate was 1.7 images per second due to interleaved biplanar image acquisition.