Off-resonance binomial composite pulses in 2D and 3D fat/water imaging at 0.5 T.
A new method of acquiring two-dimensional (2D) and three-dimensional (3D) fat/water decomposed images on a 0.5 T magnetic resonance (MR) imaging system is described. The method uses a gradient-recalled echo (GRE) sequence incorporating a composite 121 pulse, originally used for magnetization transfer contrast (MTC) experiments, for frequency-selective pre-saturation. By applying the 121 pulse off resonance, a sharp discrimination between the chemically shifted water and fat signals may be obtained using a composite pulse as short as 4 ms. Phantom studies demonstrate that suppression ratios as high as 50:1 are achievable. The new method has been applied to volunteers and patients, and good fat/water images of limb, abdomen, head and neck obtained. The new method can be incorporated into other pulse sequences related to GRE, such as phase contrast (PC) and time-of-flight (TOF), and represents the first practical (i.e. rapid) method for 3D fat/water imaging at an operating field as low as 0.5 T.
Zhu
X P
XP
Department of Diagnostic Radiology, University of Manchester, UK.
Hutchinson
C E
CE
Chilvers
P B
PB
Morris
G A
GA
Hawnaur
J M
JM
Taylor
C J
CJ
D000273:Adipose Tissue / Q000033:anatomy & histology*; D001834:Body Water; D003198:Computer Simulation; D006392:Hemangioma, Cavernous / Q000175:diagnosis; D006801:Humans; D007866:Leg / Q000033:anatomy & histology; D008113:Liver Neoplasms / Q000175:diagnosis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008961:Models, Structural; D009333:Neck / Q000033:anatomy & histology; D009915:Orbit / Q000033:anatomy & histology