Water/Fat Sequence Development
We developed fast interleaved water/fat (IWF) imaging sequences based on spectral-spatial excitation to acquire water-only and fat-only images in a single acquisition time, and to combine the water and fat images to produce chemical-shift-free images. These sequences save half of the imaging time over the conventional separate fat-suppressed and non-fat-suppressed scans. In addition, with the chemical shift corrected, the shadow artifacts often seen at water and fat boundaries are removed. Moreover, the water-only images provide better fat signal suppression than the conventional fat-saturation technique. These sequences have been used for musculoskeletal and body imaging.
A pulse sequence diagram for the IWF gradient echo (GRE) sequence is shown in (a). In the wrist images, the IWF water (b) and fat (c) images demonstrate good water and fat separation. The IWF water+fat image (d) removes chemical shift artifacts (arrows) that may obscure diagnosis in the conventional GRE image (e). In the pelvis images, the IWF water image (f) shows better fat signal suppression in the peripheral fat regions than the fat-saturated GRE image (g).
- Kwok WE, You Z, Seo G, Lerner A, Totterman S, Ritchlin C, Monu J. High-Resolution Interleaved Water-Fat MR Imaging of Finger Joints. J Magn Reson Imaging. J Magn Reson Imaging 2011;33:245-251.
- Kwok WE, You Z, Zhong J. Fast breath-hold imaging of the liver with SMASH and interleaved water/fat acquisition. In: Proceedings of Radiological Society of North America Annual Meeting, Chicago 2003, p475
- Kwok WE, You Z, Totterman SM, Zhong J. Fast Parallel MR Imaging with Interleaved Water/Fat Acquisition. Radiology 2002, 225P, p313.
- Kwok WE, Totterman SMS, Zhong J. Interleaved water and fat dual-echo spin echo imaging with intrinsic chemical-shift elimination. J Magn Reson Imaging 2001;13:318-323.
- Kwok WE, Totterman SMS, Zhong J. Three-dimensional Interleaved Water and Fat Image Acquisition with Chemical-shift Correction. Magn Reson Med 2000; 44:322-330.
Other Research Work / Collaborations
- Hornak JP, Yuan H, Kennedy SD, Kwok E. A Selectable Diffusion Coefficient Phantom based on Restricted Diffusion. In: Proceedings of ISMRM 19th Scientific Meeting and Exhibition, Montreal, Canada 2011, p3976.
- Schwarz E, Wolenski M, Turner A, Reinholds D, Kwok E, et al. A Rabbit Model of Meniscal Injury and Healing Using dGEMRIC Imaging to Assess Repair. In: Proceedings of 55th Annual Meeting of the Orthopaedic Research Society, Las Vegas, Nevada, 2009, Poster 1197.
- Lancianese SL, Kwok E, Beck CA, Lerner AL. Predicting Regional Variations in Trabecular Bone Mechanical Properties within the Human Proximal Tibia using MR Imaging. BONE 2008;43(6):1039-1046.
- Yamamoto A, Sano T, Otonari-Yamamoto M, Nishikawa, K, Kwok E. A potential reference point for assessment of condylar bone marrow of the temporomandibular joint on proton density weighted images. The Journal of Craniomandibular Practice 2008;26(4): 246-252.
- Wong CK, Kennedy S, Kwok E, Zhong J. Theoretical studies of the effect of the dipolar field in multiple spin-echo sequences with refocusing pulses of finite duration. J Magn Reson. 2007;185(2):247-258.
- Ashton E, Durkin E, Kwok E, Evelhoch J. Conversion from Signal Intensity to Gd Concentration May be Unnecessary for Perfusion Assessment of Tumors Using DCE. In: Proceedings of ISMRM 15th Scientific Meeting and Exhibition, Berlin, Germany 2007, p.2813.
- Shibata DK, Kwok E. Temporal lobe perfusion in the deaf: MR measurement with pulsed arterial spin labeling (FAIR). Academic Radiology 2006;13(6):738-743.
- Lancianese S, Kwok E, Salo AD, Lerner AL. MR Imaging of Trabecular Bone Quantify Bone Volume Fraction and Predict Mechanical Properties. In: Proceedings of Biomedical Engineering Society Annual Fall Meeting, Chicago 2006, poster 152.
- Lee PL, Yiannoutsos CT, Ernst T, Chang L, Marra CM, Jarvik JG, Richards TL, Kwok E, at. el. A multi-center 1H MRS study of the AIDS dementia complex: Validation and preliminary analysis. J Magn Reson Imaging 2003;17:625-633.
- Zhong J, Chen Z, Kwok WE, Kennedy SK, You ZG. Optimization of BOLD sensitivity in MR imaging using intermolecular double-quantum coherence (iDQC). J Magn Reson Imaging 2002;16:733-740.