A single-scan T2* mapping method based on two gradient-echo images with compensation for macroscopic field inhomogeneity.
T2*-weighted imaging (T2*WI) and quantitative T2* mapping with conventional gradient-echo acquisition are often hindered by severe signal loss induced by macroscopic field inhomogeneity. Various z-shimming approaches have been developed for T2*WI/T2* mapping in which the effects of macroscopic field inhomogeneity are suppressed while the sensitivity of T2*-related signal intensity to alterations in the microscopic susceptibility is maintained. However, this is often done at the cost of significantly increased imaging time. In this work, a fast T2* mapping method with compensation for macroscopic field inhomogeneity was developed. A proton density-weighted image and a composite T2*-weighted image, both of which were essentially free from macroscopic field inhomogeneity-induced signal loss, were used for the T2* calculation. The composite T2*-weighted image was reconstructed from a number of gradient-echo images acquired with successively incremented z-shimming compensation. Because acquisition of the two images and z-shimming compensation were realized in a single scan, the total acquisition time for obtaining a T2* map with the proposed method is the same as the time taken for a conventional multiecho gradient-echo imaging sequence without compensation. The performance and efficiency of the proposed method were demonstrated and evaluated at 4.7 T.
Meng
Yuguang
Y
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China.
Lei
Hao
H
D000465:Algorithms; D000818:Animals; D016477:Artifacts; D001185:Artificial Intelligence; D001921:Brain / Q000033:anatomy & histology*; D017352:Echo-Planar Imaging / Q000295:instrumentation / Q000379:methods*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D019047:Phantoms, Imaging; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique