Abstract:
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Purpose: We recently developed a new fast MR imaging technique that combines interleaved water/fat (IWF) technique with VD-AUTO-SMASH parallel imaging technique. The former saves half of the imaging time over conventional fat-suppressed and non-fat-suppressed imaging. The latter reduces scan time by using multiple-array RF coil acquisition to reduce the number of phase encoding steps. In this study, we test the feasibility of applying the combined technique to breath-hold imaging of the liver.
Methods and Materials: The study was conducted on a GE Signa 1.5T scanner. For IWF acquisition, a 2D GRE sequences were modified with a 1-3-3-1 binomial spatial-spectral excitation. The phase-encoding lines were interleaved with alternating water and fat RF excitation separated by half the repetition time (TR). For parallel imaging, VD-AUTO-SMASH technique was used in which full matrix images were reconstructed from partially acquired phase encoding k-space data. An overall reduction factor of 2 was used. A new sequence implementing both IWF and VD-AUTO-SMASH techniques was developed on the scanner. The livers of 5 normal subjects were imaged using the new sequence and a GE 4-element torso phased array coil. The imaging parameters are TR/TE = 100ms/15ms, flip angle 30 deg, FOV 36cm, 8mm slice, and 512x256 matrix. Images were also acquired using conventional GRE sequence with similar imaging parameters for comparison. The scan time for the conventional sequence is 26 sec. After imaging, the raw data were transferred to a workstation for image reconstruction.
Results: The VD-AUTO-SMASH IWF images acquired in a fraction of time have similar appearence as the IWF images and the conventional images. Images acquired on purposedly moving subjects also show reduced motion artifacts with VD-AUTO-SMASH IWF techniques.
Conclusion: We have applied a fast parallel MR imaging technique with interleaved water/fat acquisition for imaging of the liver. The results show that MR scan time can be reduced by a factor of 4 using a commercial 4-element torso array RF coil without lowering the image quality. Further reduction in scan time with parallel imaging can be achieved with more coil elements in the phased array. Our technique also has the additional benefits of providing water, fat and water+fat images at identical slice locations, giving superior fat-suppression in the water image, and eliminating chemical-shift artifacts from the water+fat image. It may be useful for imaging the liver of patients and liver donors, particularly those who cannot tolerate long breath-hold.
Questions about this event email: edmund_kwok@urmc.rochester.edu
Kwok PhD, W,
Fast Parallel and Interleaved Water-Fat MR Breathhold Imaging of the Liver. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3101607.html
