A HALF-FOURIER GRADIENT-ECHO TECHNIQUE FOR DYNAMIC MR-IMAGING

Recently we developed the simultaneous dual FLASH (SDFLASH) pulse sequ ence that simultaneously obtains sequential images from the brain and the internal-carotid arteries in the neck with 1-sec temporal resoluti on using a standard MR scanner. The high temporal resolution (1 sec) o f the SDFLASH technique was achieved partly by using a low number of p hase-encoding views which thereby limited our in-plane spatial resolut ion to 6.25 x 3.12 mm pixels. To overcome this limitation we have deve loped a calibration technique which corrects distortions in signal int ensity and object shape when using gradient echo half-Fourier spin war p imaging. Using this calibration technique, the operator can use the 41% decrease in scan time to either double the spatial or temporal res olution. We have successfully used this technique to acquire SDFLASH i mages of the head and neck with 1.0 sec temporal resolution and 3.12 x 1.6 mm spatial resolution.