In this paper, we describe a method for detecting and correcting in-plane bulk translational motion in multislice spin-echo imaging using self-calibration and postprocessing. A constant phase encoding offset between slices is used to evenly spread out the low spatial frequency echoes to allow accurate motion detection by self-calibration. Motion detection in both x and y directions is achieved by interchanging the readout and phase encoding directions for the alternate slices. Displacements are determined by cross correlating the modulus of each 1D transformed echo with a reference box car function whose width equals that of the imaged object. In addition, phase errors induced by the velocity in the readout direction are estimated and corrected using the displacement data. The results obtained from knee studies at 0.5 T and 1.5 T show that the artifacts due to translational motions are significantly suppressed upon correction. The method does not require any additional pulses or time, and the data processing can be easily implemented.
SUMMARYThis research paper proposes a novel method for estimating the cross-sectional shape of an LSI wafer from a stereo image of an electron microscope. Three-dimensional measurement of an LSI wafer is critical in systems that perform nondestructive dimensional measurement of integrated circuits. In this method, the secondary electron intensity is converted to a three-dimensional shape by using the relationship between the three-dimensional shape and the secondary electron intensity produced when an electron beam is directed to an LSI wafer. A three-dimensional shape can be restored with greater detail by employing an energy minimization method. As a result, the proposed method can stably restore a detailed three-dimensional shape in comparison with the conventional stereo matching method. Since the proposed method restores a three-dimensional shape using a process that is the inverse of the stereo matching method, the proposed method is called the "inverse stereo matching method," and experimental results obtained using an electron micrograph taken of the LSI wafer show the effectiveness of the proposed method.
We present an imaging technique that affords direct and noninvasive visualization of brain surface structure. This technique utilizes the signal before the rf pulse in steady-state free precession. This signal highly reflects the spin-spin relaxation time T2 as was studied in our laboratory (Matsui et al. J. Magn. Reson. 62, 12, 1985). Therefore the cerebrospinal fluid (CSF), having a long T2, is depicted as high intensity. The CSF permeates cerebral sulci and fissures. The imaging time with this technique is less than 1 min.
SUMMARYIn MR angiography, which is effective for screening of aneurysms, investigation for the quality of highresolution angiography method using the combination of asymmetric measurement with half scan reconstruction are presented. In addition to avoiding the flow void by the asymmetric measurement, it was found that there were improvements of (1) blood contrast by isolation of small vessels and static regions; (2) blood continuation by interpolation in 3-dimensional space; and (3) relative S/N of small vessels with the increasing resolution. Experimental results show that good contrast image is obtained by this method with no penalty of scanning time.
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