Breathing motion is one of the main sources of artifacts in MRI acquisitions that can severely impair diagnosis. In MRI with continuously moving table, the application of common motion compensation approaches such as breath holding or the synchronization of the measurement with the breathing motion can be problematic. In this study, a technique for the reduction of breathing-motion artifacts for MRI with continuously moving table is presented, which reconstructs motion-consistent volumes from data acquired during free breathing. Axial images are acquired rapidly compared to the period of the breathing motion and consistently combined using a combination of rigid and nonrigid slice-to-volume registration. This new technique is compared to a previously reported artifact reduction method for MRI with continuously moving table that is based on the same acquisition scheme. While the latter method only suppresses ghosting artifacts, the new technique is shown to additionally reduce blurring, misregistrations, and signal cancellations in the reconstructed images. Magn Reson Med 63: 701-712, 2010.
Deuterium nuclear magnetic resonance relaxation studies were performed on sandstones, carbonates, and synthetic porous samples. The magnetization decay in the rotating frame TIp is a stretched exponential in rock samples. The relaxation time in porous media is related to the absolute permeability by the relation k = C( TIP )2(p. We show that Tip is proportional to the width of the pore size distribution and the permeability, and is proportional to the water saturation in partially saturated rock. These results provide new methods for estimating absolute permeability and saturation.
In this study, a method for whole-body diffusion-weighted imaging (wbDWI) during continuous table motion has been developed and implemented on a clinical scanner based on a short-Tau inversion recovery echo-planar DWI sequence. Unlike currently available multistation wbDWI, which has disadvantages such as long scanning times, poor image quality, and troublesome data realignment, continuously moving
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