FLUOROSCOPIC MR IMAGING AT 0.064 TESLA

We have developed a system for ultrafast MRI protocols at low field. The system design permits us to acquire the raw data in the background while the reconstruction and display steps repeat as fast as they can in the foreground. The performance speed that one can achieve depends partly on the desired use. One of the more attractive applications is a "real-time" locator scan. By collecting raw data at a rate of 20 ms (TR) per echo with an echo delay (TE) of 9 ms, a complete data cycle for a 128 * 64 image takes 1.28 s, however, once half of that data is incorporated into the reconstruction the image appears complete. Using this set of parameters we are able to get the rate of the recon/display loop to paint about two times per completed raw data cycle showing an entirely new image at least once per second with an apparent frame rate of two per second. Interleaving of two or three orthogonal scans reduces the speed of update but provides better information. We discuss our system design for rapid scan/recon/display and demonstrate the image quality available at low field strength with scan times below one second.