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Fat suppression for ultrashort echo time imaging using a single‐point Dixon method
Author(s) -
Jang Hyungseok,
Carl Michael,
Ma Yajun,
Jerban Saeed,
Guo Tan,
Zhao Wei,
Chang Eric Y.,
Du Jiang
Publication year - 2019
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.4069
Subject(s) - image contrast , contrast (vision) , nuclear magnetic resonance , physics , signal (programming language) , nuclear medicine , chemistry , computer science , optics , medicine , programming language
Purpose In ultrashort echo time (UTE) imaging, fat suppression can improve short T 2 * contrast but can also reduce short T 2 * signals. The conventional two‐point Dixon (2p‐Dixon) method does not perform well due to short T 2 * decay. In this study, we propose a new method to suppress fat for high contrast UTE imaging of short T 2 tissues, utilizing a single‐point Dixon (1p‐Dixon) method. Methods The proposed method utilizes dual‐echo UTE imaging, where UTE is followed by the second TE, chosen flexibly. Fat is estimated by applying a 1p‐Dixon method to the non‐UTE image after correction of phase errors, which is used to suppress fat in the UTE image. In vivo ankle and knee imaging were performed at 3 T to evaluate the proposed method. Result It was observed that fat and water signals in tendons were misestimated by the 2p‐Dixon method due to signal decay, while the 1p‐Dixon method showed reliable fat and water separation not affected by the short T 2 * signal decay. Compared with the conventional chemical shift based fat saturation technique, the 1p‐Dixon based approach showed much stronger signal intensities in the Achilles, quadriceps, and patellar tendons, with significantly improved contrast to noise ratios (CNRs) of 11.8 ± 2.2, 16.0 ± 1.6, and 26.8 ± 1.3 with the 1p‐Dixon method and 0.6 ± 0.2, 4.6 ± 1.0, and 17.5 ± 1.4 with regular fat saturation, respectively. Conclusion The proposed 1p‐Dixon based fat suppression allows more flexible selection of imaging parameters and more accurate fat and water separation over the conventional 2p‐Dixon in UTE imaging. Moreover, the proposed method provides much improved CNR for short T 2 tissues over the conventional fat saturation method.