Voxel-based analysis of R2 maps in the healthy human brain

• Published in: Journal of magnetic resonance imaging Vol. 26; no. 6; pp. 1413 - 1420
• Main Authors: Péran, Patrice, Hagberg, Gisela, Luccichenti, Giacomo, Cherubini, Andrea, Brainovich, Valentina, Celsis, Pierre, Caltagirone, Carlo, Sabatini, Umberto
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.12.2007; Wiley-Blackwell
• Subjects: Adult; brain; Brain Mapping - methods; Female; Humans; Image Enhancement - methods; Image Processing, Computer-Assisted - methods; Least-Squares Analysis; Life Sciences; Magnetic Resonance Imaging - methods; Male; Reproducibility of Results; Sensitivity and Specificity; voxel based analysis
• ISSN: 1053-1807; 1522-2586
• DOI: 10.1002/jmri.21204

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. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.