Longitudinal stability of MRI for mapping brain change using tensor-based morphometry.
Measures of brain change can be computed from sequential MRI scans, providing valuable information on disease progression, e.g., for patient monitoring and drug trials. Tensor-based morphometry (TBM) creates maps of these brain changes, visualizing the 3D profile and rates of tissue growth or atrophy, but its sensitivity depends on the contrast and geometric stability of the images. As part of the Alzheimer's Disease Neuroimaging Initiative (ADNI), 17 normal elderly subjects were scanned twice (at a 2-week interval) with several 3D 1.5 T MRI pulse sequences: high and low flip angle SPGR/FLASH (from which Synthetic T1 images were generated), MP-RAGE, IR-SPGR (N = 10) and MEDIC (N = 7) scans. For each subject and scan type, a 3D deformation map aligned baseline and follow-up scans, computed with a nonlinear, inverse-consistent elastic registration algorithm. Voxelwise statistics, in ICBM stereotaxic space, visualized the profile of mean absolute change and its cross-subject variance; these maps were then compared using permutation testing. Image stability depended on: (1) the pulse sequence; (2) the transmit/receive coil type (birdcage versus phased array); (3) spatial distortion corrections (using MEDIC sequence information); (4) B1-field intensity inhomogeneity correction (using N3). SPGR/FLASH images acquired using a birdcage coil had least overall deviation. N3 correction reduced coil type and pulse sequence differences and improved scan reproducibility, except for Synthetic T1 images (which were intrinsically corrected for B1-inhomogeneity). No strong evidence favored B0 correction. Although SPGR/FLASH images showed least deviation here, pulse sequence selection for the ADNI project was based on multiple additional image analyses, to be reported elsewhere.
Leow
Alex D
AD
Laboratory of Neuro Imaging, Brain Mapping Division, Department of Neurology and Semel Institute of Neuroscience, UCLA School of Medicine, 635 Charles E. Young Drive South, Suite 225E, Los Angeles, CA 90095-7332, USA.
Klunder
Andrea D
AD
Jack
Clifford R
CR
Toga
Arthur W
AW
Dale
Anders M
AM
Bernstein
Matt A
MA
Britson
Paula J
PJ
Gunter
Jeffrey L
JL
Ward
Chadwick P
CP
Whitwell
Jennifer L
JL
Borowski
Bret J
BJ
Fleisher
Adam S
AS
Fox
Nick C
NC
Harvey
Danielle
D
Kornak
John
J
Schuff
Norbert
N
Studholme
Colin
C
Alexander
Gene E
GE
Weiner
Michael W
MW
Thompson
Paul M
PM
D000368:Aged; D000704:Analysis of Variance; D001921:Brain / Q000033:anatomy & histology*; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results