Pattern recognition for rapid T2 mapping with stimulated echo compensation.
Indirect echoes (such as stimulated echoes) are a source of signal contamination in multi-echo spin-echo T2 quantification and can lead to T2 overestimation if a conventional exponential T2 decay model is assumed. Recently, nonlinear least square fitting of a slice-resolved extended phase graph (SEPG) signal model has been shown to provide accurate T2 estimates with indirect echo compensation. However, the iterative nonlinear least square fitting is computationally expensive and the T2 map generation time is long. In this work, we present a pattern recognition T2 mapping technique based on the SEPG model that can be performed with a single pre-computed dictionary for any arbitrary echo spacing. Almost identical T2 and B1 maps were obtained from in vivo data using the proposed technique compared to conventional iterative nonlinear least square fitting, while the computation time was reduced by more than 14-fold.
Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, MA, USA; Department of Radiology, Harvard Medical School, Boston, MA, USA. Electronic address: huang.chuan@mgh.harvard.edu.
Chuan
C
Huang
Department of Medical Imaging, University of Arizona, Tucson, AZ, USA.
Maria I
MI
Altbach
Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Department of Imaging, Massachusetts General Hospital, Boston, MA, USA; Department of Radiology, Harvard Medical School, Boston, MA, USA.
Georges
G
El Fakhri
D000465:Algorithms; D016477:Artifacts; D001185:Artificial Intelligence; D001921:Brain / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
Indirect echoes; MR parameter; Quantitative MRI; Slice imperfection; Stimulated echoes; T2 mapping