PURPOSE: To develop a voxel-based analysis of an R2* map of healthy human brain that is automatic, reproducible, and realizable in a single examination on a 3T MR imager. Such a tool could be useful to measure iron accumulation in neurodegenerative diseases. MATERIALS AND METHODS: In all, 18 healthy subjects underwent MR imaging at a field strength of 3T: 1) six consecutive T2*-weighted gradient-echo volumes were acquired using a segmented echo-planar imaging sequence and 2) a conventional dual-echo turbo spin echo sequence was also applied to acquire T2-weighted images. Images were realigned and spatial correction was performed using a template brain dataset with SPM2. For each subject we performed a voxel-by-voxel nonlinear least-squares fitting of the data acquired at the six echo times to obtain a monoexponential signal decay curve. The reproducibility and sensitivity to age variation were assessed by voxel-based analysis. RESULTS: The reproducibility tests in whole brain analysis showed little R2* variation. Furthermore, the statistical analysis, performed on each brain voxel, revealed a significant positive correlation between age and MR values located in regions where a slow and constant age-related iron deposition is known. CONCLUSION: Our method, combining data acquisition and data processing, demonstrates the feasibility of voxel-based analysis on an R2* map and affords a high degree of sensitivity and good reproducibility while maintaining high spatial resolution. (c) 2007 Wiley-Liss, Inc.
PURPOSE: To develop a voxel-based analysis of an R2* map of healthy human brain that is automatic, reproducible, and realizable in a single examination on a 3T MR imager. Such a tool could be useful to measure iron accumulation in neurodegenerative diseases. MATERIALS AND METHODS: In all, 18 healthy subjects underwent MR imaging at a field strength of 3T: 1) six consecutive T2*-weighted gradient-echo volumes were acquired using a segmented echo-planar imaging sequence and 2) a conventional dual-echo turbo spin echo sequence was also applied to acquire T2-weighted images. Images were realigned and spatial correction was performed using a template brain dataset with SPM2. For each subject we performed a voxel-by-voxel nonlinear least-squares fitting of the data acquired at the six echo times to obtain a monoexponential signal decay curve. The reproducibility and sensitivity to age variation were assessed by voxel-based analysis. RESULTS: The reproducibility tests in whole brain analysis showed little R2* variation. Furthermore, the statistical analysis, performed on each brain voxel, revealed a significant positive correlation between age and MR values located in regions where a slow and constant age-related iron deposition is known. CONCLUSION: Our method, combining data acquisition and data processing, demonstrates the feasibility of voxel-based analysis on an R2* map and affords a high degree of sensitivity and good reproducibility while maintaining high spatial resolution. (c) 2007 Wiley-Liss, Inc.
Authors: Erik K Kastman; Auriel A Willette; Christopher L Coe; Barbara B Bendlin; Kris J Kosmatka; Donald G McLaren; Guofan Xu; Elisa Canu; Aaron S Field; Andrew L Alexander; Mary Lou Voytko; T Mark Beasley; Ricki J Colman; Richard H Weindruch; Sterling C Johnson Journal: J Neurosci Date: 2010-06-09 Impact factor: 6.167
Authors: Yiming Xiao; Vladimir Fonov; Silvain Bériault; Fahd Al Subaie; M Mallar Chakravarty; Abbas F Sadikot; G Bruce Pike; D Louis Collins Journal: Int J Comput Assist Radiol Surg Date: 2014-05-20 Impact factor: 2.924
Authors: Jason Langley; Daniel E Huddleston; Xiangchuan Chen; Jan Sedlacik; Nishant Zachariah; Xiaoping Hu Journal: Neuroimage Date: 2015-02-28 Impact factor: 6.556