Long-axis MR images (4.0 msec repetition time, 2.0 msec echo time, 70° flip angle, 240 mm2 field of view, 160 × 160 matrix, 8 mm section thickness, 2 frames per second) acquired in water bath containing nitinol catheter and different active coil elements. a: Only the external surface coil elements were active. b: Only the catheter coil was active. c: Only the catheter tip microcoil was active. d: Both surface coil elements and active catheter coil are contributing to the image. Reprinted with permission from Saeed et al (65).