Browsing by Subject "Weighted combination"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Open Access Enhanced phase-sensitive SSFP reconstruction for fat-water separation in phased-array acquisitions(John Wiley and Sons Inc., 2016) Yılmaz, Özgür; Sarıtaş, Emine Ülkü; Çukur, TolgaPurpose: To propose and assess a method to improve the reliability of phase-sensitive fat–water separation for phased-array balanced steady-state free precession (bSSFP) acquisitions. Phase-sensitive steady-state free precession (PS-SSFP) is an efficient fat–water separation technique that detects the phase difference between neighboring bands in the bSSFP magnetization profile. However, large spatial variations in the sensitivity profiles of phased-array coils can lead to noisy phase estimates away from the coil centers, compromising tissue classification. Materials and Methods: We first perform region-growing phase correction in individual coil images via unsupervised selection of a fat-voxel seed near the peak of each coil's sensitivity profile. We then use an optimal linear combination of phase-corrected images to segregate fat and water signals. The proposed method was demonstrated on noncontrast-enhanced SSFP angiograms of the thigh, lower leg, and foot acquired at 1.5T using an 8-channel coil. Individual coil PS-SSFP with a common seed selection for all coils, individual coil PS-SSFP with coil-wise seed selection, PS-SSFP after coil combination, and IDEAL reconstructions were also performed. Water images reconstructed via PS-SSFP methods were compared in terms of the level of fat suppression and the similarity to reference IDEAL images (signed-rank test). Results: While tissue misclassification was broadly evident across regular PS-SSFP images, the proposed method achieved significantly higher levels of fat suppression (P < 0.005) and increased similarity to reference IDEAL images (P < 0.005). Conclusion: The proposed method enhances fat–water separation in phased-array acquisitions by producing improved phase estimates across the imaging volume. J. Magn. Reson. Imaging 2016;44:148–157. © 2015 Wiley Periodicals, Inc.Item Open Access Phase-sensitive reconstruction for fat-water separation in multi-coil acquisitions(IEEE, 2016) Yılmaz, Özgür; Sarıtaş, Emine Ülkü; Çukur, TolgaPhase-sensitive steady-state free precession (PS-SSFP) is an effective technique for separating fat and water tissues, based on the phase difference between balanced steady-state free precession (bSSFP) bands. However, in phased-array coils, spatial sensitivity variations lead to noisy data away from coil centers and thereby degrade tissue classification. In this paper, we propose a new method to improve robustness of phase-sensitive fat-water separation against sensitivity variations.